AJP - Heart Calcium Transients and Cell-Sarcomere
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Am J Physiol Heart Circ Physiol 290: H209-H216, 2006. First published August 19, 2005; doi:10.1152/ajpheart.00208.2005
0363-6135/06 $8.00
This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow All Versions of this Article:
290/1/H209    most recent
00208.2005v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via ISI Web of Science (9)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Carello, K. A.
Right arrow Articles by D'Alecy, L. G.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Carello, K. A.
Right arrow Articles by D'Alecy, L. G.

Asymmetrical dimethylarginine plasma clearance persists after acute total nephrectomy in rats

Katari A. Carello,1 Steven E. Whitesall,1 Mary C. Lloyd,1 Scott S. Billecke,1 and Louis G. D'Alecy1,2,3

Departments of 1Molecular and Integrative Physiology and 2Surgery (Vascular), University of Michigan Medical School, Ann Arbor, Michigan; and 3Department of Surgery, William Beaumont Hospital, Royal Oak, Michigan

Submitted 3 March 2005 ; accepted in final form 15 August 2005


   ABSTRACT
TOP
 ABSTRACT
MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 GRANTS
 REFERENCES
 
Elevated plasma concentrations of symmetrical dimethylarginine (SDMA) and asymmetrical dimethylarginine (ADMA) are repeatedly associated with kidney failure. Both ADMA and SDMA can be excreted in urine. We tested whether renal excretion is necessary for acute, short-term maintenance of plasma ADMA and SDMA. Sprague-Dawley rats underwent sham operation, bilateral nephrectomy (NPX), ureteral ligation, or ureteral section under isoflurane anesthesia. Tail-snip blood samples (250 µl) were taken before and at 6- or 12-h intervals for 72 h after operation. Plasma clearance was assessed in intact and NPX rats. High-performance liquid chromatography determined SDMA and ADMA concentrations. Sodium, potassium, creatinine, blood urea nitrogen (BUN), and body weight were also measured. Forty-eight hours after NPX, SDMA increased 25 times (0.23 ± 0.03 to 5.68 ± 0.30 µM), whereas ADMA decreased (1.17 ± 0.08 to 0.73 ± 0.08 µM) by 38%. Creatinine and BUN increased, paralleling SDMA. Sham-operated animals showed no significant changes. Increased SDMA confirms continuous systemic production of SDMA and its obligatory renal excretion, much like creatinine. In contrast, decreased plasma ADMA suggests that acute total NPX either reduced systemic ADMA formation and/or systemic hydrolysis of ADMA increased 48-h post-NPX. However, plasma clearance of ADMA appeared unchanged 48 h after NPX. We conclude that renal excretory function is needed for SDMA elimination but not needed for acute, short-term ADMA elimination in that systemic hydrolysis is fully capable of clearing plasma ADMA.

nitric oxide synthase inhibitor; dimethylarginine dimethylaminohydrolase; source of asymmetrical dimethylarginine

AWARENESS OF THE PHYSIOLOGICAL IMPORTANCE of nitric oxide (NO) continues to grow as our basic understanding of the control of NO synthase (NOS) accumulates (12, 35). Endogenous inhibitors of NOS, such as asymmetrical (ADMA) dimethylarginine (DMA) and NG-monomethyl-L-arginine (L-NMMA) have been found to inhibit NOS (13, 61). In addition to the biological actions of ADMA in vivo, ADMA is also a reliable marker for cardiovascular disease (11). In selected populations it is an excellent predictor of cardiovascular events (62, 63) and mortality in the intensive care unit (43).

Elevated plasma ADMA levels have been reported in hypercholesterolemia (6), hypertension (57), hyperhomocyst(e)inemia (56), peripheral arterial occlusive disease (7), experimental hemorrhage (4), preeclampsia (17), hyperglycemia (37), and insulin resistance in patients (55). Even hindlimb ischemia may independently trigger the release of ADMA as suggested by indirect evidence for release of an endogenous NOS inhibitor in response to acute hindlimb ischemia (23–26). A recent review of Fliser et al. (19) traces the progression of ADMA, an innocent marker, to its current position as a leading candidate for a mediator of atherosclerotic complications in patients. In contrast, the physiological control, origins, and fates of this endogenous NOS inhibitor has yet to be fully defined.

In 1970, Kakimoto and Akazawa (27) first reported the natural occurrence of ADMA and symmetrical DMA (SDMA) in human urine and detected concentrations >30% higher than that of arginine in urine. In contrast, the plasma ADMA and SDMA concentrations they reported were <0.5% (0.3 µM) of the concentration of arginine (55.8 µM) in the plasma, reflecting a dramatic urinary concentrating effect on ADMA and SDMA and unequivocally demonstrating their renal excretion.

By 1976, intravenous injections of radiolabeled, methylated arginines were used to demonstrate that L-NMMA and ADMA were catabolized in some way, whereas SDMA was largely unchanged in urine excreted (39). Ogawa et al. (47) later identified an enzyme that hydrolyzed ADMA to citrulline. This enzyme, dimethylarginine dimethylaminohydrolase (DDAH), has been identified in the heart, brain, lung, liver, and skeletal muscle and has been shown to have particularly high activity in the kidney and pancreas (48). Although significant hydrolysis of SDMA in vivo has yet to be reported in the literature (47), Siroen et al. (53) have recently demonstrated that the human liver takes up SDMA as well as ADMA. Thus, for ADMA, the general capacity for both renal excretion and DDAH hydrolysis has been established.

The kidneys are a likely focal point for exploring the physiological control of plasma ADMA, because elevated ADMA has been often reported in association with renal failure (29, 64, 65, 68). Infusion of subpressor doses of ADMA has been shown to decrease effective renal plasma flow in humans (33). With mildly pressor doses, ADMA has been shown to decrease effective renal plasma flow and to reduce cardiac output (32). Current literature, including a study of some investigatiors from our own laboratory (51), repeatedly correlates reduced renal function with elevated plasma ADMA. However, such correlations do not establish causality. Most recently, elevated plasma ADMA has been shown not only to be inversely related to glomerular filtration rate (GFR) but also to be a strong and independent risk marker for the progression of end-stage renal disease and mortality (49). Even in mild to moderate kidney disease, elevated plasma ADMA has been shown to be an independent predictor of disease progression (20). These latter authors speculated that elevated plasma ADMA may even promote progression of renal (vascular) disease. It is possible, then, that elevated plasma ADMA could be both caused by reduced renal function and contribute to the progressive loss of renal function, particularly GFR.

This study focuses on a presumed role of the kidney in determining the plasma concentrations of ADMA and SDMA (collectively DMA). Although our understanding of plasma clearance of ADMA continues to evolve, some authors have suggested that the loss of renal excretory function is responsible for elevated ADMA levels (57, 64). The experiments presented here were not designed to model end-stage renal disease but to test the hypothesis that acute loss of renal function is capable of, and indeed responsible for, increasing plasma ADMA and SDMA. In addition, we have used bilateral nephrectomy (2xNPX), ureteral section, and ureteral occlusion protocols in rats as definitive mechanistic experiments to determine the necessity for renal excretory and synthetic roles in acutely maintaining plasma ADMA and SDMA. Plasma clearance, in contrast to renal clearance of ADMA in NPX rats, was used as a surrogate for post-NPX in vivo DDAH activity. Our novel observation is that removal of the kidneys acutely decreases plasma ADMA rather than increases plasma ADMA and that renal excretory function is needed for SDMA elimination but is not needed for ADMA clearance.


   MATERIALS AND METHODS
TOP
 ABSTRACT
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
 GRANTS
 REFERENCES
 
Adult male Sprague-Dawley rats (200–400 g; Charles River) were anesthetized with isoflurane via chamber induction (5%) and mask maintenance (1–2.5%). Fed or 24-h fasted animals with free access to water underwent acute 2xNPX through either bilateral flank incisions or a single dorsal midline incision. Separate groups underwent bilateral ureteral section or ligation through a 1-cm midline incision over the bladder. The ureters were isolated at their entrance to the bladder and either sectioned or ligated bilaterally. Sham-operated animals received anesthesia, incisions, and manipulation but no NPX, ureteral section, or ligation. Blood samples (250 µl into heparin-coated tubes) were taken before operation or sham operation and at 6- or 12-h intervals for 48 h in the ligation and ureteral section protocols and up to 72 h in the NPX protocol using a standard tail-snip method in a heated restraint. Animals surviving 72 h were anesthetized with isoflurane and euthanized with pentobarbital sodium (150 mg/kg ip). Peritoneal fluid from the ureteral-section rats was sampled for analysis, and total fluid volume was estimated by weighing sponges collected from the cavity. All animals were housed in metabolic cages on a 12-h:12-h light-dark cycle. Animal care complied with APS "Principles of Laboratory Animal Care" and the Guide for the Care and Use of Laboratory Animals of the National Institutes of Health (NIH Publication No. 85-23, Revised 1996). All protocols were approved by the University Committee for the Use and Care of Animals (approval 8355 and 8666).

Quantification of blood pH and hematocrit and plasma proteins, creatinine, BUN, sodium, and potassium.

Whole blood pH was determined by using a blood gas analyzer (Radiometer ABL system 605, Copenhagen, Denmark) within 5 min of the blood being drawn. Hematocrit was determined in duplicate by using a centrifugation method. Plasma protein concentrations were determined in quadruplicate by using a Coomassie Plus Bradford assay kit (Pierce, Rockford, IL) per the manufacturer's instructions and analyzed spectrophotometrically (Beckman model 34 spectrophotometer). Plasma creatinine levels were determined spectrophotometrically (Sigma kit 555; Bauch and Lomb Spectronic 20) using calibration curves with an R2 of ≥0.99 (Sigma creatinine standards 925–3 and 925–15). Blood urea nitrogen (BUN) was measured spectrophotometrically by a quantitative enzymatic colorimetric assay (Sigma kit 640-A; Beckman model 34 spectrophotometer). Sodium and potassium were measured by using standard flame photometry.

Plasma DMA clearance protocol.

Three additional groups of anesthetized rats were used to assess plasma clearance of ADMA and SDMA. Each group (intact, acute 2xNPX, and 48-h 2xNPX) had the same protocol to establish an elevated steady-state concentration of ADMA and SDMA from which clearance (washout) was determined by stopping the infusion and repeatedly sampling as concentrations returned toward baseline. An intravenous bolus (1 mg/kg) of both ADMA and SDMA was followed immediately by an infusion of 0.05 mg·kg–1·min–1. To confirm steady-state plasma levels, arterial blood samples were taken at 60, 80, and 90 min during infusion after which the infusion was stopped. Precisely timed samples were taken at 3, 6, 9, 15, 27, and 51 min, thus allowing plasma concentration to decline from the steady-state levels toward baseline. Each sample was at or below 100 µl, such that <5% total blood volume was withdrawn and plasma was separated and filtered for HPLC analysis.

Sample preparation for ADMA and SDMA assay.

Heparinized plasma (100 µl) was ultrafiltered through a 10,000-mol wt cutoff membrane of regenerated cellulose (Ultrafree MC, Millipore, Bedford, MA) at 16,000 g for 20 min at 4°C. The filtrate was spiked 1:6 (20–100 µl) with L-NMMA (Novabiochem, San Diego, CA) as an internal standard for solid phase extraction. The spiked filtrate was extracted by loading 60 µl onto 50 mg of conditioned (1 ml 100% methanol) and equilibrated (1 ml 2% TCA) cation exchange, silica-based sorbent (Isolute SCX2, 50 mg/1 ml, International Sorbent Technology). Each loaded sample was sequentially gravity rinsed with 0.5 ml of the equilibration solution, 2 ml of a 15 mM (pH 8.00) sodium phosphate, and 0.5 ml of 100% methanol. Sample analytes were eluted by vacuum with 1.5 ml of eluant (10% TEA, 10% NH4OH, 20% H2O, and balance methanol) and evaporated to dryness in air at 60°C. The dry residue was reconstituted and derivatized with 80 µl of a pH 8.2 borate buffer and 20 µl of fluorescent derivatizing agent (AccQ·Fluor, Waters, Milford, MA). After 1 min of incubation, the 100 µl were transferred to a low-volume insert and heated (55°C) for 10 min to complete reaction before injection on the column.

High-performance liquid chromatography.

The DMAs ADMA and SDMA in plasma samples were quantified by reverse-phase liquid chromatography (Breeze System, Waters). A two-pump gradient system and column heater (Binary HPLC Pump 1525, Waters) delivered 88% to 86% (at 34 min) to 0% 10 mM sodium acetate trihydrate (pH 4.76) with balance methanol at 1 ml/min for 49 min. Separation was performed on a 4.6 mm x 150 mm, 3.5 µm column (XterraMS C18, Waters) with an identical 3.9 mm x 20 mm guard column, both controlled at 36°C. Standards, blanks, and samples (10 µl) were injected (717Plus Autosampler, Waters), and fluorescent peak height and area were evaluated at an excitation of 250 nm and an emission of 395 nm (2475 Multi-wavelength Fluorescence Detector, Waters) to 0.1 µM original concentrations. Standard curves were produced for 0, 0.37, 0.75, 1.5, and 3.0 µM ADMA and SDMA, and chromatograms showed stable retention times, and substantial peak separation were apparent. The average method detection limit (MDL; 46a) was calculated from 3 sets of 10 replicates in plasma and standards and is 0.07 µM for SDMA and 0.13 µM for ADMA. The average intra-assay coefficient of variations (CVs) (2 assays of n = 4 samples) for ADMA and SDMA (1.5 µM standard) were 2.4 and 3.3%, respectively. Intra-assay CVs (n = 8 samples) for ADMA and SDMA in pooled rat plasma (mean of 1.1 µM) were 2.2 and 3.2%, respectively. The inter-assay CV (n = 4 samples) for 1.5 µM was 2.6% for ADMA and 0.3% for SDMA. Assay results are presented in micromolars.

Statistical analysis

Measured variables are means ± SE and were considered statistically significant using the paired two-tailed Student's t-test if P ≤ 0.05. The plasma ADMA and SDMA post-NPX time-course values were not statistically and significantly different between fed and fasted groups; therefore, the data have been pooled to a single group of NPX animals (n = 10) and compared with sham-operated control animals (n = 8).


   RESULTS
TOP
 ABSTRACT
 MATERIALS AND METHODS
 RESULTS
DISCUSSION
 GRANTS
 REFERENCES
 
2xNPX.

Figure 1A shows a progressive decline in plasma ADMA to 53% of baseline values by 72 h after 2xNPX. Simultaneously, there was a dramatic increase in plasma SDMA (Fig. 1B) in contrast with sham-operated animals that showed no sustained change in either ADMA or SDMA. Although the kidney is capable of excreting both ADMA and SDMA, these data demonstrate that the removal of both kidneys caused opposite effects of decreasing plasma ADMA concentration and simultaneously increasing plasma SDMA concentration.



View larger version (16K):
[in this window]
[in a new window]
  		Fig. 1. A: plasma asymmetrical (ADMA) dimethylarginine (DMA) time course of sham-operated ({blacksquare}) and postnephrectomy (post-NPX; {square}) rats. NPX reduces ADMA concentration. B: plasma symmetrical DMA (SDMA) time course of sham-operated ({bullet}) and post-NPX ({circ}) rats. NPX increases SDMA concentration. A and B: sham-operated (n = 8) and NPX (n = 10) rats, unless otherwise indicated by numbers in parentheses adjacent to symbols. In B, SE (not visible) are within the symbol.

 
Only half the 2xNPX animals survived the full 72 h. Subsequent protocols and comparisons were done at 48 h after 2xNPX (Table 1). The average plasma concentrations at 48 h, when 9 of the 10 rats were still alive, show that SDMA increased by 25 times, whereas ADMA decreased to 62% of baseline values. These opposite effects on SDMA and ADMA were both statistically significant. Table 1 also shows data from a separate group of 2xNPX rats, which indicate the expected increase in plasma creatinine, BUN, and potassium and relatively stable plasma sodium, total protein, and hematocrit. The pH declined by 0.10 pH, and there was a <10% decline in body weight at 48-h post-NPX. The increase in SDMA is similar to the increase in plasma creatinine, suggesting that 2xNPX eliminates the excretory mechanism for both SDMA and creatinine.


View this table:
[in this window]
[in a new window]
  		Table 1. Control values and values at 48-h postnephrectomy

 
Figure 2A contrasts the effects of 2xNPX, bilateral ureteral section, or bilateral ligation on plasma ADMA. There was ~50% reduction of plasma ADMA in 48 h due to either 2xNPX or ligation; however, plasma ADMA was maintained in rats undergoing bilateral ureteral section. When the mass (volume x concentration) of ADMA in the peritoneal cavity of the ureteral-sectioned rats is mathematically added to the ADMA mass in the plasma, the calculated plasma concentration would be 3.53 ± 0.45 µM or almost three times their actual measured plasma concentration. Thus the kidney with the sectioned ureter excreted, albeit into the peritoneum, large quantities of ADMA over the 2-day period. However, with ureteral ligation, there was apparently a reduction in formation of ADMA and/or an increase in systemic hydrolysis, because the plasma concentration of ADMA fell to levels similar to the 2xNPX group. Figure 2B contrasts the increase in SDMA due to 2xNPX with more modest increases due to ureteral ligation and ureteral section. When the mass of SDMA in the peritoneal cavity of the ureteral-sectioned rats is mathematically added to the mass in the plasma, the calculated SDMA plasma concentration would be 6.18 ± 0.41 µM or almost three times their actual measured plasma concentration. Thus the kidney in the ureteral-sectioned rats continues to excrete large quantities of SDMA into the peritoneal cavity.



View larger version (14K):
[in this window]
[in a new window]
  		Fig. 2. A: plasma ADMA decreasing in response to bilateral NPX and ureteral ligation while remaining steady after ureteral section. B: plasma SDMA increasing in response to bilateral NPX and ureteral ligation and ureteral section.

 
Plasma clearance of DMA.

The plasma steady-state concentrations of DMAs produced by the bolus plus infusion protocols were verified by three sequential samples at 60, 80, and 90 min (data not shown), just before the infusion pump was turned off. The steady-state average of these three time points is shown in Fig. 3 and is the starting point for the clearance curves in Fig. 4. The same bolus injection and infusion protocol was used in all three groups (intact, acute NPX, and 48-h NPX), such that the same steady-state plasma concentration would have been obtained if production, excretion, and/or hydrolysis rates had not changed. However, Fig. 3 shows a statistically significant increase (44%) in steady-state ADMA concentration within 2 h after 2xNPX. Given that identical bolus and infusion protocols were used in intact and 2xNPX animals, these data suggest either an increased production or a more likely acute decreased clearance due to acute loss of renal excretory function with acute 2xNPX. In contrast, the steady-state ADMA concentration produced by infusion at 48 h after 2xNPX was not statistically different from intact animals. Either production declined or there was a compensatory increase in any clearance mechanisms still remaining after 2xNPX that would presumably be from DDAH hydrolysis. With acute 2xNPX, the SDMA concentration increased dramatically (71%), suggesting a similar acute loss of renal excretory function for clearance. However, SDMA concentration continued to increase until 48 h, suggesting no compensatory change in production or hydrolysis as seen with ADMA.



View larger version (13K):
[in this window]
[in a new window]
  		Fig. 3. ADMA (solid bars) and SDMA (open bars) concentrations at steady-state concentration produced by identical bolus plus infusion protocols in each group. Acute NPX increases ADMA but 48 h later ADMA has returned to intact levels.

 


View larger version (18K):
[in this window]
[in a new window]
  		Fig. 4. A: washout of ADMA from steady-state concentration produced by identical bolus plus infusion protocols in each group. B: SDMA. For both panels, SE (not visible) are within the symbol.

 
The analysis of the profile of the ADMA clearance curves (Fig. 4A) failed to clearly identify an altered overall systemic clearance in either the acute 2xNPX or the 48-h 2xNPX group. A dominating role for DDAH in overall plasma clearance of ADMA is suggested. Rapid blood sampling in the first 3 min was not done, and that may have been able to resolve an initial clearance difference attributable to renal excretion of ADMA in the intact rats. The clearance curve data for SDMA (Fig. 4B) show little or no decline in plasma steady-state concentration for SDMA in both the acute and 48-h 2xNPX groups, thus confirming an absence of significant nonrenal clearance mechanisms for SDMA.


   DISCUSSION
TOP
 ABSTRACT
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
GRANTS
 REFERENCES
 
Acute 2xNPX is not a model of end-stage renal disease. Acute 2xNPX is, in the classical physiological tradition, a mechanistic experimental manipulation to definitively determine whether the kidneys are needed for the acute elimination or clearance of ADMA. The data presented here demonstrate that acute removal of the kidneys does not increase plasma ADMA. However, as predicted, SDMA markedly increased. These data call into question the previous conclusion of many investigators, including some of our own investigators (53), that deterioration of renal excretory function observed in multiple disease states is responsible for elevated plasma ADMA. Although plasma ADMA unquestionably increases in virtually every renal disease state, this correlation with renal excretory failure does not establish causality.

The plasma concentrations of DMAs are the result of a balance between formation and elimination (11, 13). The only known mechanism for SDMA elimination in the rat is renal excretion (40, 44). The data from this study confirm this by showing an ongoing increase in plasma SDMA concentration after 2xNPX. Furthermore, with acute loss of renal excretory function, we observed parallel increases in plasma SDMA and creatinine concentration. This SDMA-creatinine correlation has been previously reported in fasting human subjects where no such correlation between ADMA and creatinine was observed (45).

In contrast with the increases in SDMA after NPX, we observed simultaneous decreases in ADMA after NPX. Although both ADMA and SDMA are presumably continuously formed, the elimination of plasma ADMA varies and appears to have both a renal excretory component and a component of hydrolysis to citrulline by DDAH. New evidence also suggests that the liver may contribute significantly to ADMA clearance in rats and humans (41, 54). The balance of formation and elimination (by excretion and hydrolysis) determines the plasma concentration. Bilateral NPX removes not only the renal excretory function but also an established tissue source of ADMA as indicated by the demonstration of protein arginine methyl transferases (PRMTs) in the kidney (58) and the high tissue levels of ADMA reported for renal tissues (3).

Several studies further support the idea that plasma ADMA levels may not correlate as closely with renal function as previously thought. Kielstein et al. (30) report that in patients with incipient renal disease, inulin clearance was strongly correlated with SDMA but poorly correlated with ADMA clearance. This study also showed that ADMA was elevated in renal failure patients with a normal GFR. Furthermore, after renal transplantation in chronic renal failure patients, SDMA returns to baseline, whereas ADMA remains elevated (18).

A growing body of evidence suggests that DDAH may be a significant route of elimination for ADMA. Of the total ADMA produced daily in humans, only 20% is excreted by the kidneys, whereas DDAH metabolizes the remaining 80% (1). This trend appears to be present in the rat where DDAH metabolizes >90% of ADMA (47). Thus a large fraction of the plasma clearance of ADMA is attributable to baseline DDAH activity. Furthermore, DDAH activity can be modulated in vivo and in vitro. DDAH activity decreased with exposure of endothelial cells to oxidized LDL (22) and was also decreased in rat models of Type 2 diabetes (37). Although these authors report a decrease in DDAH activity with an increase in ADMA, it does support the idea that systemic conditions can modify DDAH activity. Although DDAH has high activity in the kidney (48), there is also wide tissue distribution (36, 48, 59, 60). DDAH is even present in red blood cells (28). Thus, even with the removal of renal DDAH and ADMA excretion in the urine, a small increase in systemic DDAH activity could compensate for the loss of the kidneys and their relatively small excretory contribution to total ADMA clearance.

In the washout protocol (Fig. 4), steady-state SDMA remains elevated in 48-h 2xNPX animals, whereas ADMA decreased from a steady-state infusion level at a rate similar to the intact controls; i.e., the net plasma clearance of ADMA appears similar in these two cases. This suggests that at 48 h, the balance of infusion, endogenous formation, and endogenous hydrolytic activity (presumably by DDAH) produces the same plasma concentration that was observed in the intact group that had, in addition, renal excretion of DMAs. However, when plasma DMAs are examined immediately after 2xNPX (acute NPX group), there is a significant (P = 0.002) increase in plasma ADMA concentration despite identical infusion rates, suggesting an acute, and not yet compensated for, loss of plasma clearance mechanisms for ADMA. We conclude that this reflects the acute removal of renal excretory function before any systemic compensation. In the subsequent 48 h, other plasma clearance mechanisms compensate and take the place of renal clearance. By 48-h post-NPX, the same steady-state plasma concentration was obtained that was observed in the intact preparation, but this remained so by using a slightly different set of clearance mechanisms.

Plasma concentrations of ADMA can affect clearance rates. Any increase in DDAH specific activity (i.e., per mg DDAH protein) could be obscured (or mimicked) by the effect of the higher plasma levels of ADMA produced after acute NPX. A higher hydrolysis rate in the acute NPX group is expected due to higher initial steady-state substrate concentration. These concentrations (10–15 µM) are well below the Km for DDAH (28, 47). According the Michaelis-Menton kinetics, the higher the plasma concentration of ADMA, the greater the effective rate of DDAH hydrolysis. The higher ADMA hydrolysis rate (plasma clearance) would be matched at 48 h by an increased hydrolysis at a lower substrate concentration, because through compensation the system has increased DDAH expression or specific activity. The overall effective rates are very similar but are based on different initial concentrations and specific activities (or expression). Testing after 48 h allowed time for either increased expression or altered specific activity due to changes in the enzymes environment.

Reports of decreasing ADMA in the face of unchanged renal uptake and function are not unique to our laboratory's findings. Indeed other systemic alterations, such as endotoxemia (40), have been shown to decrease plasma ADMA. These authors also report an increase in hepatic uptake in association with endotoxemia. Another possible explanation for our results could be an increase in ADMA uptake by the y+ transporter. Closs et al. (10) demonstrated that both ADMA and SDMA are transported across the y+ carrier hCAT-2B. Y+ activity has also been found to increase in response to many exogenous stimuli (8, 38, 66). Thus it is conceivable that y+ carrier transport of ADMA could increase in response to uremia in the NPX animals.

Another potential explanation for the reduction in ADMA that we observed may be related to modulation of DDAH activity by zinc and/or pH. Knipp et al. (34) described the negative regulation of DDAH activity by zinc, which when removed by chelation, dramatically enhanced hydrolytic activity in their purified enzyme system. With a possible physiological significance to DDAH regulation by zinc, Sachin and Gordon (50) showed that after 2xNPX of rats, plasma zinc concentrations fell from 89 to 60 µg/100 ml over 24 h. This 33% level of reduction in plasma zinc may be sufficient to allow for the activation of DDAH, resulting in enhanced degradation of ADMA and therefore potentially explaining the reduction of plasma ADMA levels that we observed. In addition, it might be tempting to speculate that the tendency for NPX to acidify the blood (Table 1, pH 7.41 to pH 7.31) might aid in the activation of DDAH, because the early work by Ogawa et al. (48) indicated that DDAH was active between pH 5.5 and pH 7.5 but optimal at pH 6.5. This early observation, however, was likely due to the zinc-chelating effect of the phosphate buffer used in their in vitro reaction. Indeed, Knipp et al. (34) show convincing evidence that this is the case and further describe the optimal pH for zinc-deficient DDAH activity to be ~7.4.

Other possibilities, although less likely, include intravascular dilution, negative feedback on formation, and loss of a preferential ADMA reservoir. Our observed decrease in ADMA does not appear to be due to hemodilution, because both total plasma proteins and hematocrit are statistically unchanged 48-h post-NPX (Table 1) and trending in opposite directions. Our plasma protein concentrations are similar to those reported by others (21), and our changes in hematocrit also agree with the literature for 48-h post-NPX in rats (69). Thus, although the trend we observed in hematocrit (42% to 40%) would support some small hemodilution effect, the tendency was not statistically significant, and the trend toward increased protein concentration was in the opposite direction for hemodilution. A further argument against hemodilution contributing significantly to the observed reduction in plasma ADMA concentration is that creatinine, BUN, potassium, and SDMA all increased significantly (P < 0.001) after NPX, whereas body weight decreased by 7% (Table 1). If an expansion of the plasma volume had occurred, it would have needed to be of sufficient magnitude to reduce the plasma ADMA concentration by ~40%. Such a dilution effect would be expected to simultaneously reduce the concentration of other solutes in the plasma. However, this did not occur, and, in fact, the concentration of SDMA increased by 25 times, creatinine increased by 38 times, and BUN increased by 16 times rather than decreasing. Thus intravascular dilution is not a likely explanation for reduced plasma ADMA concentration.

The marked increase in plasma SDMA after NPX opens the possibility that there was a negative feedback of SDMA on ADMA formation. However, the literature suggests a negative feedback is unlikely in that simultaneous elevations of both plasma DMAs have been reported in peripheral arterial occlusive disease (7) and in end-stage renal disease (67, 68). The loss of a preferential ADMA reservoir by NPX is possible in that particularly high kidney tissue levels of ADMA have been reported (3). However, Nijveldt et al. reported net renal extraction, not synthesis, of ADMA in humans (45) and rats (42). Other sources of ADMA, such as isolated human endothelial cells in culture, have also been reported (16). Furthermore, Al Banchaabouchi et al. (3) report that plasma ADMA increased in rats subjected to 80% partial NPX. Thus the loss of a renal reservoir of ADMA is a much too simplistic explanation for our results.

Recent literature (13, 14) has linked the renin-angiotensin system (RAS) with ADMA levels. Given the central role that the kidney plays in the RAS, it is possible that renal manipulations (NPX, ligation, and section) could alter RAS and thus impact ADMA levels. A 50% reduction in plasma angiotensin II and an undetectable renin activity have been reported for rats 48 h after NPX (2, 9). The literature for RAS changes in ligation, and section remains less well defined (5, 14, 46), and significant variations of plasma renin activity has been reported in patients with unilateral and bilateral hydronephrosis (15). Thus, without detailed assessment of RAS in our model, speculation about such associations is inappropriate.

With the data from this study we are definitely not questioning the ability of the kidneys to excrete ADMA. The kidneys are clearly capable of ADMA excretion. In fact, Al Banchaabouchi et al. (3) gave compelling evidence for the ability for ADMA excretion in rats, mice, and humans. In their subtotal NPX (40% or 80% NPX in rat), they actually showed an eightfold increase in excretion of ADMA. It is not surprising, however, that after a 3-wk recovery from an 80% NPX that the rats of Al Banchaabouchi et al. had significantly compensated renal excretory function. The control and subtotal NPX creatinine excretion (127.8 ± 19.8 vs. 137.6 ± 26.7 µmol/24 h, respectively) were not even statistically different, illustrating the remarkable renal compensatory capacity.

Multiple laboratories (30, 64, 65, 67, 68), including Rajagopalan's laboratory (51), have reported elevated plasma ADMA concentrations in renal failure patients. Renal dialysis has been reported to reduce plasma ADMA (31). Kielstein et al. (30) have even detected elevated ADMA in plasma of patients with incipient primary chronic renal disease. Puromycin nephrosis in the rat produces hypertension by focal and segmental glomerulosclerosis (52), and Sato et al. (52) demonstrated a significant positive correlation between systolic blood pressure and plasma and urinary ADMA. With all of these correlative studies, including our own, none have demonstrated a cause and effect relationship between renal failure and increased plasma ADMA. It is often asserted that in renal failure there is a partial compromise of renal excretion of ADMA, and this failure is responsible for elevating plasma ADMA concentrations. The data presented here are the first to challenge these assertions. Having the ability to excrete ADMA does not mean that ADMA must be excreted to be cleared from the plasma. Furthermore, finding ADMA in the urine does not prove that failure of renal excretion causes the increase in plasma ADMA.

In conclusion, based on our NPX and plasma clearance data, we conclude that control of systemic hydrolysis of ADMA (e.g., by DDAH) and/or the control of its formation (e.g., PRMT activity) can maintain essentially normal plasma clearance of ADMA in the absence of the kidneys. ADMA does not require the kidneys for its elimination from the plasma. By controlling plasma ADMA concentration, the balance of activity of synthetic and degradative pathways for ADMA presents yet another mechanism for modulating regional blood flow and arterial blood pressure by controlling NOS and NO vascular smooth muscle relaxation in NO-dependent vascular beds.


   GRANTS
TOP
 ABSTRACT
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 GRANTS
REFERENCES
 
This study was supported in part by National Heart, Lung, and Blood Institute Grant HL-18575, Program Project 5 P01 HL-1857524, and by T35 2T35 HL-07690–21A1 training grant (to K. Carello) for the University of Michigan Medical School's Summer Biomedical Research Program.


   ACKNOWLEDGMENTS
 
We thank The Ravitz Foundation (Southfield, MI), for support of Dr. Scott Billecke, and Dr. Carrie Rose, for performing the initial series of bilateral nephrectomies and assays.


   FOOTNOTES
 

Address for reprint requests and other correspondence: L. G. D'Alecy, Dept. of Molecular and Integrative Physiology, Univ. of Michigan Medical School, 7708 Medical Sciences Bldg. II, 1301 E. Catherine, Ann Arbor, MI 48109-0622 (e-mail:lgdalecy{at}umich.edu)

The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.


   REFERENCES
TOP
 ABSTRACT
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 GRANTS
 REFERENCES
 

  1. Achan V, Broadhead M, Malaki M, Whitley G, Leiper J, MacAllister R, and Vallance P. Asymmetric dimethylarginine causes hypertension and cardiac dysfunction in humans and is actively metabolized by dimethylarginine dimethylaminohydrolase. Arterioscler Thromb Vasc Biol 23: 1455–1459, 2003.[Abstract/Free Full Text]
  2. Aguilera G, Schirar A, Baukal A, and Catt KJ. Circulating angiotensin II and adrenal receptors after nephrectomy. Nature 289: 507–509, 1981.[CrossRef][Medline]
  3. Al Banchaabouchi M, Marescau B, Possemiers I, D'Hooge R, Levillain O, and De Deyn PP. NG, NG-dimethylarginine and NG, NG-dimethylarginine in renal insufficiency. Pflügers Arch 439: 524–531, 2000.[CrossRef][ISI][Medline]
  4. Aneman A, Backman V, Snygg J, von Bothmer C, Fandriks L, and Pettersson A. Accumulation of an endogenous inhibitor of nitric oxide synthase during graded hemorrhagic shock. Circ Shock 44: 111–114, 1994.[ISI][Medline]
  5. Ayan S, Roth JA, Freeman MR, Bride SH, and Peters CA. Partial ureteral obstruction dysregulates the renal renin-angiotensin system in the fetal sheep kidney. Urology 58: 301–306, 2001.[CrossRef][ISI][Medline]
  6. Boger RH, Bode-Boger SM, Szuba A, Tsao PS, Chan JR, Tangphao O, Blaschke TF, and Cooke JP. Asymmetric dimethylarginine (ADMA): a novel risk factor for endothelial dysfunction: its role in hypercholesterolemia. Circulation 98: 1842–1847, 1998.[Abstract/Free Full Text]
  7. Boger RH, Bode-Boger SM, Thiele W, Junker W, Alexander K, and Frolich JC. Biochemical evidence for impaired nitric oxide synthesis in patients with peripheral arterial occlusive disease. Circulation 95: 2068–2074, 1997.[Abstract/Free Full Text]
  8. Bogle RG, Coade SB, Moncada S, Pearson JD, and Mann GE. Bradykinin and ATP stimulate L-arginine uptake and nitric oxide release in vascular endothelial cells. Biochem Biophys Res Commun 180: 926–932, 1991.[CrossRef][ISI][Medline]
  9. Campbell DJ, Kladis A, and Duncan AM. Nephrectomy, converting enzyme inhibition, and angiotensin peptides. Hypertension 22: 513–522, 1993.[Abstract/Free Full Text]
  10. Closs EI, Basha FZ, Habermeier A, and Forstermann U. Interference of L-arginine analogues with L-arginine transport mediated by the y+ carrier hCAT-2B. Nitric Oxide 1: 65–73, 1997.[CrossRef][ISI][Medline]
  11. Cooke JP. Asymmetrical dimethylarginine: the Uber marker? Circulation 109: 1813–1818, 2004.[Free Full Text]
  12. Cooke JP. Does ADMA cause endothelial dysfunction? Arterioscler Thromb Vasc Biol 20: 2032–2037, 2000.[Abstract/Free Full Text]
  13. Cooke JP. The pivotal role of nitric oxide for vascular health. Can J Cardiol 20, Suppl B: 7B–15B, 2004.
  14. Elfont RM and Fitzsimons JT. Renin dependence of captopril-induced drinking after ureteric ligation in the rat. J Physiol 343: 17–30, 1983.[Abstract/Free Full Text]
  15. Ezzat M. The pattern of plasma renin activity and aldosterone system in patients with sustained hydronephrosis. Int Urol Nephrol 19: 55–63, 1987.[Medline]
  16. Fickling SA, Leone AM, Nussey SS, Vallance P, and Whitley GS. Synthesis of NG, NG dimethylarginine by human endothelial cells. Endothelium 1: 137–140, 1993.[CrossRef]
  17. Fickling SA, Williams D, Vallance P, Nussey SS, and Whitley GS. Plasma concentrations of endogenous inhibitor of nitric oxide synthesis in normal pregnancy and pre-eclampsia. Lancet 342: 242–243, 1993.[ISI][Medline]
  18. Fleck C, Janz A, Schweitzer F, Karge E, Schwertfeger M, and Stein G. Serum concentrations of asymmetric (ADMA) and symmetric (SDMA) dimethylarginine in renal failure patients. Kidney Int Suppl 78: S14–S18, 2001.[Medline]
  19. Fliser D. Asymmetric dimethylarginine (ADMA): the silent transition from an "uraemic toxin" to a global cardiovascular risk molecule. Eur J Clin Invest 35: 71–79, 2005.[CrossRef][ISI][Medline]
  20. Fliser D, Kronenberg F, Kielstein JT, Morath C, Bode-Boger SM, Haller H, and Ritz E. Asymmetric dimethylarginine and progression of chronic kidney disease: the mild to moderate kidney disease study. J Am Soc Nephrol 16: 2456–2461, 2005.[Abstract/Free Full Text]
  21. Hernandez I, Carbonell LF, Quesada T, and Fenoy FJ. Role of angiotensin II in modulating the hemodynamic effects of nitric oxide synthesis inhibition. Am J Physiol Regul Integr Comp Physiol 277: R104–R111, 1999.[Abstract/Free Full Text]
  22. Ito A, Tsao PS, Adimoolam S, Kimoto M, Ogawa T, and Cooke JP. Novel mechanism for endothelial dysfunction: dysregulation of dimethylarginine dimethylaminohydrolase. Circulation 99: 3092–3095, 1999.[Abstract/Free Full Text]
  23. Jin JS and D'Alecy LG. Central and peripheral effects of asymmetric dimethylarginine, an endogenous nitric oxide synthetase inhibitor. J Cardiovasc Pharmacol 28: 439–446, 1996.[CrossRef][ISI][Medline]
  24. Jin JS and D'Alecy LG. Stimulation of endogenous nitric oxide pathway by L-arginine reduces declamp mortality and attenuates hypertension associated with aortic cross-clamp-induced hindlimb ischemia in rats. Hypertension 26: 406–412, 1995.[Abstract/Free Full Text]
  25. Jin JS, Webb RC, and D'Alecy LG. Inhibition of vascular nitric oxide-cGMP pathway by plasma from ischemic hindlimb of rats. Am J Physiol Heart Circ Physiol 269: H254–H261, 1995.[Abstract/Free Full Text]
  26. Jin JS, Wilde DW, Webb RC, and D'Alecy LG. Calcium channel activity increased by plasma from ischemic hindlimbs of rats: role of an endogenous NO synthase inhibitor. Am J Physiol Heart Circ Physiol 270: H1484–H1492, 1996.[Abstract/Free Full Text]
  27. Kakimoto Y and Akazawa S. Isolation and identification of NG,NG- and NG,N' G-dimethyl-arginine, N-epsilon-mono-, di-, and trimethyllysine, and glucosylgalactosyl- and galactosyl-delta-hydroxylysine from human urine. J Biol Chem 245: 5751–5758, 1970.[Abstract/Free Full Text]
  28. Kang ES, Cates TB, Harper DN, Chiang TM, Myers LK, Acchiardo SR, and Kimoto M. An enzyme hydrolyzing methylated inhibitors of nitric oxide synthase is present in circulating human red blood cells. Free Radic Res 35: 693–707, 2001.[ISI][Medline]
  29. Kielstein JT, Bode-Boger SM, Frolich JC, Haller H, and Boger RH. Relationship of asymmetric dimethylarginine to dialysis treatment and atherosclerotic disease. Kidney Int Suppl 78: S9–S13, 2001.[CrossRef][Medline]
  30. Kielstein JT, Boger RH, Bode-Boger SM, Frolich JC, Haller H, Ritz E, and Fliser D. Marked increase of asymmetric dimethylarginine in patients with incipient primary chronic renal disease. J Am Soc Nephrol 13: 170–176, 2002.[Abstract/Free Full Text]
  31. Kielstein JT, Boger RH, Bode-Boger SM, Schaffer J, Barbey M, Koch KM, and Frolich JC. Asymmetric dimethylarginine plasma concentrations differ in patients with end-stage renal disease: relationship to treatment method and atherosclerotic disease. J Am Soc Nephrol 10: 594–600, 1999.[Abstract/Free Full Text]
  32. Kielstein JT, Impraim B, Simmel S, Bode-Boger SM, Tsikas D, Frolich JC, Hoeper MM, Haller H, and Fliser D. Cardiovascular effects of systemic nitric oxide synthase inhibition with asymmetrical dimethylarginine in humans. Circulation 109: 172–177, 2004.[Abstract/Free Full Text]
  33. Kielstein JT, Simmel S, Bode-Boger SM, Roth HJ, Schmidt-Gayk H, Haller H, and Fliser D. Subpressor dose asymmetric dimethylarginine modulates renal function in humans through nitric oxide synthase inhibition. Kidney Blood Press Res 27: 143–147, 2004.[CrossRef][ISI][Medline]
  34. Knipp M, Charnock JM, Garner CD, and Vasak M. Structural and functional characterization of the Zn(II) site in dimethylargininase-1 (DDAH-1) from bovine brain. Zn(II) release activates DDAH-1. J Biol Chem 276: 40449–40456, 2001.[Abstract/Free Full Text]
  35. Leiper J and Vallance P. Biological significance of endogenous methylarginines that inhibit nitric oxide synthases. Cardiovasc Res 43: 542–548, 1999.[Abstract/Free Full Text]
  36. Leiper JM, Santa Maria J, Chubb A, MacAllister RJ, Charles IG, Whitley GS, and Vallance P. Identification of two human dimethylarginine dimethylaminohydrolases with distinct tissue distributions and homology with microbial arginine deiminases. Biochem J 343: 209–214, 1999.[CrossRef][ISI][Medline]
  37. Lin KYIA, Asagami T, Tsao PS, Adimoolam S, Kimoto M, Tsuji H, Reaven G, and Cooke JP. Impaired nitric oxide synthase pathway in diabetes mellitus: role of asymmetric dimethylarginine and dimethylarginine. Dimethylaminohydrolase. Circulation 106: 987–992, 2002.[Abstract/Free Full Text]
  38. Low BC and Grigor MR. Angiotensin II stimulates system y+ and cationic amino acid transporter gene expression in cultured vascular smooth muscle cells. J Biol Chem 270: 27577–27583, 1995.[Abstract/Free Full Text]
  39. McDermott JR. Studies on the catabolism of Ng-methylarginine, Ng, Ng-dimethylarginine and Ng, Ng-dimethylarginine in the rabbit. Biochem J 154: 179–184, 1976.[ISI][Medline]
  40. Nijveldt RJ, Siroen MP, Teerlink T, van Lambalgen AA, Rauwerda JA, and van Leeuwen PA. Gut and liver handling of asymmetric and symmetric dimethylarginine in the rat under basal conditions and during endotoxemia. Liver Int 24: 510–518, 2004.[CrossRef][ISI][Medline]
  41. Nijveldt RJ, Siroen MP, Teerlink T, and van Leeuwen PA. Elimination of asymmetric dimethylarginine by the kidney and the liver: a link to the development of multiple organ failure? J Nutr 134: 2848S–2852S, 2004.[Abstract/Free Full Text]
  42. Nijveldt RJ, Teerlink T, Siroen MP, Van Lambalgen AA, Rauwerda JA, and Van Leeuwen PA. The liver is an important organ in the metabolism of asymmetrical dimethylarginine (ADMA). Clin Nutr (Edinb) 22: 17–22, 2003.[ISI][Medline]
  43. Nijveldt RJ, Teerlink T, Van Der Hoven B, Siroen MP, Kuik DJ, Rauwerda JA, and Van Leeuwen PA. Asymmetrical dimethylarginine (ADMA) in critically ill patients: high plasma ADMA concentration is an independent risk factor of ICU mortality. Clin Nutr (Edinb) 22: 23–30, 2003.[ISI][Medline]
  44. Nijveldt RJ, Teerlink T, van Guldener C, Prins HA, van Lambalgen AA, Stehouwer CD, Rauwerda JA, and van Leeuwen PA. Handling of asymmetrical dimethylarginine and symmetrical dimethylarginine by the rat kidney under basal conditions and during endotoxaemia. Nephrol Dial Transplant 18: 2542–2550, 2003.[Abstract/Free Full Text]
  45. Nijveldt RJ, Van Leeuwen PA, Van Guldener C, Stehouwer CD, Rauwerda JA, and Teerlink T. Net renal extraction of asymmetrical (ADMA) and symmetrical (SDMA) dimethylarginine in fasting humans. Nephrol Dial Transplant 17: 1999–2002, 2002.[Abstract/Free Full Text]
  46. Nobiling R, Buhrle CP, Hackenthal E, Helmchen U, Steinhausen M, Whalley A, and Taugner R. Ultrastructure, renin status, contractile and electrophysiological properties of the afferent glomerular arteriole in the rat hydronephrotic kidney. Virchows Arch A Pathol Anat Histopathol 410: 31–42, 1986.[CrossRef][ISI][Medline]
  47. Office of the Federal Register National Archives and Records Administration. Definition and procedure for determination of the method detection limit. In: Code of Federal Regulations (revised), Washington, DC: Office of the Federal Register National Archives and Records Administration, 1999, pt. 136, appendix B.
  48. Ogawa T, Kimoto M, and Sasaoka K. Occurrence of a new enzyme catalyzing the direct conversion of NG,NG-dimethyl-L-arginine to L-citrulline in rats. Biochem Biophys Res Commun 148: 671–677, 1987.[CrossRef][ISI][Medline]
  49. Ogawa T, Kimoto M, and Sasaoka K. Purification and properties of a new enzyme, NG,NG-dimethylarginine dimethylaminohydrolase, from rat kidney. J Biol Chem 264: 10205–10209, 1989.[Abstract/Free Full Text]
  50. Ravani P, Tripepi G, Malberti F, Testa S, Mallamaci F, and Zoccali C. Asymmetrical dimethylarginine predicts progression to dialysis and death in patients with chronic kidney disease: a competing risks modeling approach. J Am Soc Nephrol 16: 2449–2455, 2005.[Abstract/Free Full Text]
  51. Sachin IN and Gordon DB. Plasma zinc levels in nephrectomized and ureteral ligated rats. Proc Soc Exp Biol Med 151: 380–381, 1976.[Abstract]
  52. Saran R, Novak JE, Desai A, Abdulhayoglu E, Warren JS, Bustami R, Handelman GJ, Barbato D, Weitzel W, D'Alecy LG, and Rajagopalan S. Impact of vitamin E on plasma asymmetric dimethylarginine (ADMA) in chronic kidney disease (CKD): a pilot study. Nephrol Dial Transplant 18: 2415–2420, 2003.[Abstract/Free Full Text]
  53. Sato J, Masuda H, Tamaoki S, Hamasaki H, Ishizaka K, Matsubara O, and Azuma H. Endogenous asymmetrical dimethylarginine and hypertension associated with puromycin nephrosis in the rat. Br J Pharmacol 125: 469–476, 1998.[CrossRef][ISI][Medline]
  54. Siroen MP, van der Sijp JR, Teerlink T, van Schaik C, Nijveldt RJ, and van Leeuwen PA. The human liver clears both asymmetric and symmetric dimethylarginine. Hepatology 41: 559–565, 2005.[CrossRef][ISI][Medline]
  55. Siroen MP, Warle MC, Teerlink T, Nijveldt RJ, Kuipers EJ, Metselaar HJ, Tilanus HW, Kuik DJ, van der Sijp JR, Meijer S, van der Hoven B, and van Leeuwen PA. The transplanted liver graft is capable of clearing asymmetric dimethylarginine. Liver Transpl 10: 1524–1530, 2004.[CrossRef][ISI][Medline]
  56. Stuhlinger MC, Abbasi F, Chu JW, Lamendola C, McLaughlin TL, Cooke JP, Reaven GM, and Tsao PS. Relationship between insulin resistance and an endogenous nitric oxide synthase inhibitor. JAMA 287: 1420–1426, 2002.[Abstract/Free Full Text]
  57. Stuhlinger MC, Tsao PS, Her JH, Kimoto M, Balint RF, and Cooke JP. Homocysteine impairs the nitric oxide synthase pathway: role of asymmetric dimethylarginine. Circulation 104: 2569–2575, 2001.[Abstract/Free Full Text]
  58. Surdacki A, Nowicki M, Sandmann J, Tsikas D, Boeger RH, Bode-Boeger SM, Kruszelnicka-Kwiatkowska O, Kokot F, Dubiel JS, and Froelich JC. Reduced urinary excretion of nitric oxide metabolites and increased plasma levels of asymmetric dimethylarginine in men with essential hypertension. J Cardiovasc Pharmacol 33: 652–658, 1999.[CrossRef][ISI][Medline]
  59. Tang J, Gary JD, Clarke S, and Herschman HR. PRMT 3, a type I protein arginine N-methyltransferase that differs from PRMT1 in its oligomerization, subcellular localization, substrate specificity, and regulation. J Biol Chem 273: 16935–16945, 1998.[Abstract/Free Full Text]
  60. Tojo A, Welch WJ, Bremer V, Kimoto M, Kimura K, Omata M, Ogawa T, Vallance P, and Wilcox CS. Colocalization of demethylating enzymes and NOS and functional effects of methylarginines in rat kidney. Kidney Int 52: 1593–1601, 1997.[ISI][Medline]
  61. Tran CT, Fox MF, Vallance P, and Leiper JM. Chromosomal localization, gene structure, and expression pattern of DDAH1: comparison with DDAH2 and implications for evolutionary origins. Genomics 68: 101–105, 2000.[CrossRef][ISI][Medline]
  62. Tran CT, Leiper JM, and Vallance P. The DDAH/ADMA/NOS pathway. Atheroscler Suppl 4: 33–40, 2003.[ISI][Medline]
  63. Valkonen VP, Laakso J, Paiva H, Lehtimaki T, Lakka TA, Isomustajarvi M, Ruokonen I, Salonen JT, and Laaksonen R. Asymmetrical dimethylarginine (ADMA) and risk of acute coronary events. Does statin treatment influence plasma ADMA levels? Atheroscler Suppl 4: 19–22, 2003.[ISI][Medline]
  64. Valkonen VP, Paiva H, and Salonen JT. Risk of acute coronary events and serum concentration of asymmetrical dimethylarginine. Lancet 358: 2127–2128, 2001.[CrossRef][ISI][Medline]
  65. Vallance P, Leone A, Calver A, Collier J, and Moncada S. Accumulation of an endogenous inhibitor of nitric oxide synthesis in chronic renal failure. Lancet 339: 572–575, 1992.[CrossRef][ISI][Medline]
  66. Wahbi N, Dalton RN, Turner C, Denton M, Abbs I, and Swaminathan R. Dimethylarginines in chronic renal failure. J Clin Pathol 54: 470–473, 2001.[Abstract/Free Full Text]
  67. Wileman SM, Mann GE, and Baydoun AR. Induction of L-arginine transport and nitric oxide synthase in vascular smooth muscle cells: synergistic actions of pro-inflammatory cytokines and bacterial lipopolysaccharide. Br J Pharmacol 116: 3243–3250, 1995.[ISI][Medline]
  68. Zoccali C, Benedetto FA, Maas R, Mallamaci F, Tripepi G, Malatino LS, and Boger R. Asymmetric dimethylarginine, C-reactive protein, and carotid intima-media thickness in end-stage renal disease. J Am Soc Nephrol 13: 490–496, 2002.[Abstract/Free Full Text]
  69. Zoccali C, Bode-Boger S, Mallamaci F, Benedetto F, Tripepi G, Malatino L, Cataliotti A, Bellanuova I, Fermo I, Frolich J, and Boger R. Plasma concentration of asymmetrical dimethylarginine and mortality in patients with end-stage renal disease: a prospective study. Lancet 358: 2113–2117, 2001.[CrossRef][ISI][Medline]
  70. Zurovsky Y and Eligal Z. The effects of food and drink on the survival of binephrectomized rats. Exp Toxicol Pathol 47: 293–297, 1995.[ISI][Medline]



This article has been cited by other articles:


Home page
 Nephrol Dial TransplantHome page
S. S. Billecke, L. G. D'Alecy, R. Platel, S. E. Whitesall, K. A. Jamerson, R. L. Perlman, and C. A. Gadegbeku
Blood content of asymmetric dimethylarginine: new insights into its dysregulation in renal disease
Nephrol. Dial. Transplant., September 15, 2008; (2008) gfn500v1.
[Abstract] [Full Text] [PDF]

Home page
 J. Am. Soc. Nephrol.Home page
Y. Matsumoto, S. Ueda, S.-i. Yamagishi, K. Matsuguma, R. Shibata, K. Fukami, H. Matsuoka, T. Imaizumi, and S. Okuda
Dimethylarginine Dimethylaminohydrolase Prevents Progression of Renal Dysfunction by Inhibiting Loss of Peritubular Capillaries and Tubulointerstitial Fibrosis in a Rat Model of Chronic Kidney Disease
J. Am. Soc. Nephrol., May 1, 2007; 18(5): 1525 - 1533.
[Abstract] [Full Text] [PDF]

Home page
 J. Am. Soc. Nephrol.Home page
S. Tatematsu, S. Wakino, T. Kanda, K. Homma, K. Yoshioka, K. Hasegawa, N. Sugano, M. Kimoto, T. Saruta, and K. Hayashi
Role of Nitric Oxide-Producing and -Degrading Pathways in Coronary Endothelial Dysfunction in Chronic Kidney Disease
J. Am. Soc. Nephrol., March 1, 2007; 18(3): 741 - 749.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Physiol. Lung Cell. Mol. Physiol.Home page
P. Bulau, D. Zakrzewicz, K. Kitowska, J. Leiper, A. Gunther, F. Grimminger, and O. Eickelberg
Analysis of methylarginine metabolism in the cardiovascular system identifies the lung as a major source of ADMA
Am J Physiol Lung Cell Mol Physiol, January 1, 2007; 292(1): L18 - L24.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Physiol. Heart Circ. Physiol.Home page
S. S. Billecke, L. A. Kitzmiller, J. J. Northrup, S. E. Whitesall, M. Kimoto, A. V. Hinz, and L. G. D'Alecy
Contribution of whole blood to the control of plasma asymmetrical dimethylarginine
Am J Physiol Heart Circ Physiol, October 1, 2006; 291(4): H1788 - H1796.
[Abstract] [Full Text] [PDF]

Home page
 Nephrol Dial TransplantHome page
J. T. Kielstein, S. R. Salpeter, S. M. Bode-Boeger, J. P. Cooke, and D. Fliser
Symmetric dimethylarginine (SDMA) as endogenous marker of renal function--a meta-analysis
Nephrol. Dial. Transplant., September 1, 2006; 21(9): 2446 - 2451.
[Abstract] [Full Text] [PDF]

This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow All Versions of this Article:
290/1/H209    most recent
00208.2005v1
<