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secretion in hypertensive
and heart failure-prone rats
1 College of Pharmacy;
2 Department of Food Science and
Technology, Acute increases in blood pressure (BP) increase
myocardial tumor necrosis factor (TNF)-
spontaneously hypertensive rats; SHHF/Mcc-facp
rats; phosphodiesterase inhibitors; amrinone; RO-201724
EMPHASIS IN congestive heart failure (CHF) research has
shifted toward the development of pharmacological tools that prevent or
delay the onset of later stages of CHF (11). This emphasis necessitates
the identification of physiologically relevant mediators of progressive
deterioration of cardiac function and the use of appropriate models to
study their pathological effects. One potential mediator of CHF that
has gained attention is tumor necrosis factor (TNF)- Because it may be clinically beneficial to inhibit cardiac production
of TNF- Experimental Animals
ABSTRACT
TOP
ABSTRACT
INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES
production, but it is not
known whether chronic hypertensive stress elevates myocardial TNF-
production, possibly contributing to cardiac remodeling, decreased
cardiac function, and faster progression to heart failure. BP, cardiac function, and size were evaluated in normotensive [Sprague-Dawley (SD)], spontaneously hypertensive (SHR), and spontaneously
hypertensive heart failure-prone (SHHF) rats at 6, 12, 15, and 18 mo of
age and in failing SHHF. Left ventricular tissues were evaluated for secretion of bioactive TNF- and inhibition of TNF- secretion by
phosphodiesterase inhibitors. All ventricles secreted bioactive and
immunoreactive TNF-, but secretion decreased with age. SHR and SHHF
rats secreted more TNF- than SD rats at 6 mo of age, but only
failing SHHF rats secreted significantly more TNF- at 18 mo.
Amrinone inhibited TNF- secretion in all rats and was less potent
but more efficacious than RO-201724 in all strains. TNF- secretion
correlated with BP and left ventricular mass in 6-mo-old rats, but this
relationship disappeared with age. Results suggest that hypertension
and/or cardiac remodeling is associated with elevated myocardial
TNF-, and, although hypertension, per se, did not maintain elevated
cardiac TNF- levels, SHHF rats increase TNF- production during
the end stages of failure.
INTRODUCTION
TOP
ABSTRACT
INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES
; its presence
and function in heart failure has been suggested by many investigators
(3, 14, 25, 30, 35, 41). TNF- is a physiologically important
depressant of cardiac function during septic shock (33), and studies in
humans demonstrate that plasma TNF- is elevated in CHF patients to
concentrations that can produce left ventricular dysfunction, pulmonary
edema, and uncoupling of 
-adrenergic receptors (25, 30, 34). In addition, TNF- is a hypertrophic stimulus for cultured cardiac myocytes and alters collagen and collagenase activity and expression in
numerous cell types (2, 7, 12, 13). We and others have demonstrated
that the myocardium expresses and secretes bioactive TNF- (6, 18,
34, 42). Therefore, we hypothesized that cardiac cells produce TNF-
that acts in an autocrine fashion, contributing to the pathobiology
(i.e., decreased cardiac contractility, altered matrix production) of
CHF before appreciable increases in plasma TNF- levels occur. Recent
reports (23) demonstrate robust increases in TNF- mRNA expression
and bioactive protein production after 3 h of aortic banding (i.e.,
hypertensive stress). We hypothesized that if TNF- contributes to
cardiac remodeling and CHF, then genetically hypertensive rats prone to
developing CHF would have greater myocardial production of TNF-
compared with normotensive rats or spontaneously hypertensive rats
(SHR), which do not routinely succumb to failure. To attain these
goals, 6-, 12-, and 18-mo-old drug-naive rats of Sprague-Dawley (SD), SHR, and spontaneously hypertensive heart
failure-prone/Mcc-facp
(SHHF) strains were used. Also, SHHF rats in terminal heart failure were studied.
, we determined whether TNF- production could be modulated
using amrinone and RO-201724, type III and type IV phosphodiesterase
(PDE) inhibitors, respectively. Both type III and IV PDE inhibitors
block TNF- gene transcription and, consequently, TNF- protein
production (17, 31, 37), and it is hypothesized that inhibition of
myocardial production of TNF- by PDE inhibitors may prove to be a
useful way to study the detrimental effects of TNF- on myocardial
remodeling and progression of CHF. Amrinone and RO-201724 were chosen
to determine whether there was a differential ability of PDE inhibitors
to block TNF- release with respect to age or extent of cardiac remodeling.
METHODS
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ABSTRACT
INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES
The initial study was designed to monitor blood pressure and cardiac
function and then, after rats were killed at 6, 12, and 18 mo of age
(n = 6 per age per strain), to measure
cardiac size, TNF- secretion, and PDE inhibition of TNF-
secretion in vitro. These ages were chosen because rats
become stably hypertensive by 6 mo of age. By 12 mo of age, SHR and
SHHF rats have been chronically hypertensive, and SHHF rats have
increased neurohumoral factors, such as elevated plasma renin activity,
atrial natriuretic factor, and sympathetic nervous system activity. The
final time point of 18 mo was chosen as a time immediately before
natural onset of end-stage failure. Before completion of the initial
study, two SHHF rats that had been assigned to the 18-mo group
exhibited signs of terminal CHF. On analysis of TNF- secretion, it
appeared that failing rats had markedly different levels of TNF-
secretion compared with age-matched animals not in failure, and a
second study was conducted to increase the data collected from rats in failure (therefore, n = 6 failing SHHF
rats). In the second study 7-mo-old SHHF
(n = 5) and failing SHHF
(n = 4) rats were also evaluated for
immunologically detectable TNF- secreted into conditioned medium, in
vitro, and for left ventricular TNF- content.
Blood Pressure and Echocardiographic Measurements
Systolic blood pressure (SBP) was measured using an IITC tail-cuff pump (Woodland Hills, CA) attached to a Gilson Duograph (Gilson Medical Electronics, Middletown, WI) immediately after light anesthesia with intraperitoneal ketamine-xylazine (10 and 50 mg/kg, respectively). Echocardiograms were then obtained by performing two-dimensional and M-mode echocardiography using a color phased-array Doppler system (model Sonos 1000, Hewlett-Packard, Waltham, MA) with a dual frequency (7.5 MHz image/5.0 MHz Doppler) transducer as previously described (19). Left ventricular posterior (i.e., free wall) thickness (PWT), end-diastolic diameter (EDD), and end-systolic diameter (ESD) were derived from M-mode echocardiograms using the leading edge method. Fractional shortening was calculated as (EDD
ESD)/EDD × 100%. Relative wall thickness was calculated as (2 × PWT)/EDD.
In the 6-mo, 12-mo, 18-mo, and failing groups, SBP and echocardiograms
were performed 3-5 days before death. The rats that were
designated for death at 18 mo of age also had serial blood pressure and
echocardiographic measurements performed at 12 and 15 mo of age.
Because there were no significant differences in measurements taken at
12 mo of age from those in rats designated for death at 12 or 18 mo of
age, all 12-mo data were combined (n = 12/strain at 12 mo).
Left Ventricle Tissue Preparation
Rats were weighed and killed between 9:00 AM and 12:00 PM. Rats were anesthetized with pentobarbital sodium (100 mg/kg ip), 6-8 ml of blood were collected via cardiac puncture for subsequent measurement of circulating TNF-, and the heart was removed and perfused through a cannulated aorta with 50 ml of sterile 50% DMEM
plus 50% F-12 medium, supplemented with 2.45 g/l sodium bicarbonate and 1% penicillin-streptomycin. The heart was weighed; the right atrium, left atrium, right ventricle, and left ventricle plus septum
were dissected and weighed; and sections were frozen at 80°C. The lower one-third of the left ventricle was minced
with a razor blade into 1 × 1-mm sections and rinsed thoroughly
with DMEM to remove any remaining blood components. The minced left ventricle was then weighed and divided into 12 pieces of approximately equal weight and incubated for 4 h at 37°C in a gassed incubator (5% CO2-95% air) in 2 ml of
DMEM-5% fetal bovine serum (FBS)-1% penicillin-streptomycin (DF5).
The incubation media were collected under sterile conditions and frozen
at 80°C before evaluation for TNF- quantity. The minced
myocardium was also frozen at 80°C and then weighed before
subsequent measurement of protein and DNA content using the methods of
Lowry (26) and Burton (9), respectively.
Drugs
Left ventricular tissues were incubated with five concentrations of amrinone (obtained from the hospital pharmacy as the injectable lactate salt diluted to appropriate experimental concentrations with DF5 medium) and with five concentrations of RO-201724 [obtained from RBI, Natick, MA; dissolved in 4.5% (wt/vol) aqueous 2-hydroxypropyl--cyclodextrin and diluted to appropriate
experimental concentrations with DF5 medium].
TNF- Determination
Bioactive TNF-.
Cytotoxicity assay was performed as previously described by Matthews
and Neale (27). Briefly, L929 cells were grown in RPMI medium with 5%
FBS and antibiotics in 96-well culture plates. The cells were allowed
to incubate at 37°C overnight. The next day, actinomycin D (1 µg/ml) was added to the wells, and conditioned medium (200 µl/well)
or heat-treated serum [30 µl/well; previously heated to
56°C for 30 min and then cooled to room temperature (21)]
were applied. After another overnight incubation, the medium and serum
were decanted from the cells, and the cells were fixed with 5%
formaldehyde in PBS for 5 min and then stained with 0.5% crystal
violet for 5 min. After the cells were washed and dried, the extent of
cytotoxicity was determined using an SLC Spectra plate reader by
measuring the absorbance at 580 nm after cells were solubilized in 150 µl of 33% glacial acetic acid. The limit of detection of the
cytotoxicity assay was ~1 pg/ml with the use of recombinant mouse
TNF- as standard (3 × 108
U/mg; GIBCO). We have previously demonstrated that 80-90% of bioactivity detected by this method is neutralized using
TNF--selective antibodies and that bioactivity approximates TNF-
release from isolated adult rat cardiomyocytes and is not produced by
adherent inflammatory cells (6).
Immunoreactive TNF-.
Immunoreactive TNF- was measured in heparinized plasma from all rats
using the Factor Test X ELISA (Genzyme Diagnostics, Cambridge, MA),
which has a limit of detection of 10 pg/ml. Immunoreactive TNF- was
detected in conditioned medium and cardiac tissue using the Cytoscreen
ultrasensitive rat TNF- ELISA (BioSource International, Camarillo,
CA), which has a detection limit of <0.7 pg/ml. TNF- tissue
content was analyzed after rapid homogenization of 50-100 mg of
left ventricular tissue in 1.5 ml of 2 mM phenylmethylsulfonyl fluoride
in PBS. The homogenate was centrifuged for 10 min at 9,000 g, and then the supernatant fraction
was subjected to ELISA.
Statistical Analysis
Statistical differences among groups were evaluated using two-factor ANOVA followed by Newman-Keuls post hoc multiple-comparison tests using the Number Crunchers Statistical System (NCSS; Jerry Hintze, Kaysville, UT). IC50 values were calculated from dose-response curves obtained from individual rats, utilizing the Graph Pad statistical package. Correlation coefficients were determined using least-squares multiple regression analysis. The significance level was set at P < 0.05. All results are expressed as means ± SE.| |
RESULTS |
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DISCUSSION
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With the exception of data for the rats assigned to the failing SHHF
group, all data included in Tables 1 and
2 and in Fig. 1 were obtained from rats free of signs of
CHF. One animal was omitted from analysis in each of the 12-mo-old SHR,
18-mo-old SHR, and 18-mo-old SD groups because of evidence of apical
infarction or death due to unknown causes; therefore,
n = 5 in these age groups. In the
18-mo-old SHHF group, only four animals survived to the designated time
of death without signs of CHF; therefore, n = 4 in this group. The failing SHHF
rats [n = 6 (2 rats from study 1 and 4 rats from
study 2); age at death = 17.9 ± 0.6 mo, range = 16.5-20 mo of age] were killed when external
signs of failure appeared (massive edema, piloerection, labored
breathing) or when ejection fraction (EF) was <30% with evidence of
marked left ventricular dilatation.
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Blood Pressure and Cardiac Function Parameters
SBP did not change with age in SD rats and was significantly elevated in SHR and SHHF rats compared with SD rats at all ages (Table 1). Blood pressure was significantly higher in SHHF rats compared with SHR at 12 mo of age but was significantly decreased at 18 mo of age in SHHF rats. PWT was greater in SHHF rats at 12 mo of age and in all hypertensive rats by 15 mo of age. EDD in SD rats tended to be larger than in age-matched SHR, except at 18 mo of age. This may be a reflection of significantly greater body weights in SD rats (see Table 2). EDD in SHR remained constant until rats reached 18 mo of age, when dilatation of the chamber appears to occur. SHHF rats, which initially had larger body weights than SHR, had larger EDD at 6 mo of age. Because body weights of SHR and SHHF rats equalized with age, EDD in SHHF rats was similar to that in SHR. However, there was no dilatation of the left ventricle in 18-mo-old SHHF animals that showed no signs of CHF. All animals in the failure group showed markedly dilated chamber diameters. Calculation of relative wall thickness revealed that SHR and SHHF rats 12 mo of age and older had thicker wall-to-lumen ratios than SD rats, indicative of concentric hypertrophy. SHHF rats with signs of CHF had lower relative wall thickness, indicative of eccentric hypertrophy or fluid overload in the failing SHHF rats. Fractional shortening did not change with age in SD rats. Fractional shortening was greater in SHR and SHHF rats compared with that in SD rats at 6 mo of age, and fractional shortening in SHR and SHHF rats tended to decrease by 18 mo of age, but these values were not significant. However, all animals with heart failure showed compromised fractional shortening.Body Weight and Cardiac Weights
At 6 mo of age, body weights for SHHF rats were intermediate between those for SD rats and SHR, perhaps a reflection of the SHHF rats being a cross between SD rats and SHR. However, after the age of 12 mo, SHHF rat and SHR body weights were similar, and both were less than those of age-matched SD rats (Table 2). In general, absolute weights and weight-to-body weight ratios for the heart, left ventricle, and right ventricle were greater in all hypertensive animals by 12 mo of age (Table 2). All cardiac weight parameters were increased in animals with failure, with marked increases in heart weight index and right ventricle index.Circulating TNF-
in serum, as determined by cytotoxicity assay, was
below the level of detection in all ages of all three strains of rats.
Immunoactive TNF-, as determined by ELISA, was above the detection
limit in only one or two rats per age group per strain with the
exception of the group of 6-mo-old SHR, in which all 6 animals had
detectable plasma TNF- levels (group mean = 60 ± 27; range = 10-176 pg/ml).
Left Ventricular TNF- Secretion
secreted from 6-mo-old
normotensive controls (Fig. 1). At 12 mo of age, the amount of TNF-
secreted from the left ventricle of SD rats had not changed from the
amount secreted from 6-mo-old SD rats. However, SHR and SHHF rats
secreted significantly less TNF- at 12 mo of age than at 6 mo of
age, and neither hypertensive group secreted amounts different from
that of 12-mo-old SD rats. At 18 mo of age, the amounts of TNF-
secreted from the left ventricle of SD, SHR, and SHHF rats not showing
signs of CHF were significantly less than the amounts secreted from
6-mo-old rats from respective strains. Eighteen-month-old SHHF rats
with no overt signs of heart failure tended to secrete more TNF-
than age-matched SHR and SD rats, although this was not statistically
significant. However, SHHF rats documented to be in CHF by clinical
signs and echocardiography averaged TNF- secretion that was
threefold higher than that of 18-mo-old SD rats and SHR. These
differences were also observed when TNF- secretion was normalized to
milligrams of protein or micrograms of DNA (data not shown).
Because the bioactivity assay for TNF- can be affected by the
presence of soluble receptors and because TNF- secretion may not
accurately reflect TNF- tissue content, it is important to compare
bioactivity measurements with immunodetectable TNF- secreted into
medium and present in left ventricular tissue. Therefore, ELISAs and
cytotoxicity experiments were performed on additional samples collected
from five 7-mo-old and four failing SHHF rats (EF < 30%). As shown
in Fig. 2, secreted TNF- measured by
bioassay was comparable to secreted TNF- measured by ELISA (7-mo
bioactive = 71 ± 11% of immunoreactive TNF-; failing bioactive
TNF- = 87 ± 17% of immunoreactive TNF-). Also,
immunoreactive TNF- secreted was 25% of immunoreactive TNF-
content in the left ventricle for both 7-mo-old and failing SHHF rats.
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Correlation Analysis
To determine whether a relationship existed between 1) ambient blood pressure and TNF- release from the left ventricle,
2) left ventricular size and TNF-
release from the left ventricle, and
3) fractional shortening and TNF-
release, correlation analysis was performed using each of these
parameters for all rats. Global regression analysis revealed no
correlation among these parameters. However, subgroup analysis,
performed for groups classified by age or rat strain, revealed several
significant correlations. At 6 mo of age, blood pressure was linearly
correlated with TNF- secretion (r = 0.68, P < 0.01). At 12 and 18 mo of
age, this relationship did not exist. At 6 mo of age, there was a
highly significant linear correlation between an increase in left
ventricular size and TNF- secretion
(r = 0.757, P < 0.001) (Fig.
3) that, like the correlation seen with
blood pressure, disappeared with age. There were no significant
correlations between fractional shortening and the secretion of TNF-
from the left ventricle.
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Inhibition of TNF- Secretion by PDE Inhibitors
secretion from
the left ventricle in all groups of rats. The maximal effect of
amrinone ranged from 80 to 100% inhibition of TNF- secretion and
did not differ among the rat strains or ages. Also, the potency of
amrinone (determined by its
IC50) did not differ with
respect to age or strain (Table 3). We have
shown previously (6) that type IV PDE inhibitors such as RO-201724 have
similar efficacy but are more potent than amrinone in inhibiting
TNF- secretion in 3-mo-old SD rats. In this study, in 6-mo-old SD
rats, the efficacy of RO-201724 was similar to that of amrinone
(~80% inhibition of TNF- release) and was more potent (Table
4), consistent with the findings in
younger SD rats. Although RO-201724 remained more potent than
amrinone in all other age groups of SD and SHHF rats, the maximal
inhibitory effect of RO-2011724 was less than that observed for
amrinone; RO-201724 inhibition of TNF- secretion ranged from 44 to
68% for older SD and SHHF rats. Most striking was the relative lack of
effect of RO-201724 in SHR, in which inhibition of TNF- secretion
ranged from 30 to 50%. IC50
values for RO-201724 were not calculated for SHR because of this
marginal effect.
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DISCUSSION |
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ABSTRACT
INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES
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Because TNF- has been implicated in the pathogenesis of heart
failure, it was the goal of these studies to investigate whether TNF- secretion was altered 1) due
to chronic hypertension and 2)
during the process of cardiac remodeling and eventual progression to
heart failure. Although there are many causative factors of heart
failure (8), we chose a rat genetic model of heart failure, the
SHHF/Mcc-facp
rat, which demonstrates a natural progression from cardiac hypertrophy (due to hypertension), to a stage of compensated left ventricular dysfunction (characterized by increased circulating factors such as
atrial natriuretic peptide, plasma renin activity, and aldosterone), to
overt decompensated heart failure (characterized by cachexia, fluid
accumulation, dyspnea, and decreased
dP/dt). SHR were used as a control
for the effect of hypertension on TNF- production and to delineate
whether myocardial TNF- secretion could be used as an indicator of
which hypertensive animals were destined to succumb to heart failure.
Cardiac function and dimensions of the rats used in this study were
similar to those reported previously for SD, SHR, and SHHF rats,
suggesting consistency within these strains studied over time.
Two important points can be made with respect to TNF- production in
relation to hypertension and cardiac size/remodeling. First, the
initial stage of cardiac remodeling in response to elevated blood
pressure is coincident with increased TNF- secretion from the left
ventricle in both SHR and SHHF rats. SHR and SHHF rats become stably
hypertensive by 3-4 mo of age. During this relatively early
presence of stable hypertension and/or cardiac hypertrophy, TNF-
expression/release appears to be increased. Kapadia et al. (23) report
that there is a biophysical link between 30 min of hemodynamic
overloading and the production of TNF- in feline myocardium and that
exposure to hypertensive stress for 
180 min results in even greater
cardiac expression of TNF-. Although we observed a stronger
correlation between left ventricular size and TNF- than between SBP
and TNF-, others have shown no change in TNF- expression in
hypertrophied right ventricular tissue induced by hypobaric hypoxia
(24); this may suggest that elevated blood pressure increases TNF-,
which may play a role in cardiac remodeling. Indeed, TNF- has been
shown to alter collagenase, collagens, and fibronectin expression in
various cell types (2, 7, 12, 13). An alteration in cardiac matrix
breakdown and production may therefore assist in cardiac remodeling.
However, if hypertension is an important stimulus for TNF- secretion
during its early stages, there appears to be a loss of this regulation during prolonged hypertension.
Second, there is a general decline in bioactive TNF- release from
the left ventricle with age, independent of strain or blood pressure;
however, older SHHF rats and SHHF rats in overt CHF retain or reacquire
the ability to synthesize TNF-, and this may be important in cardiac
remodeling occurring later during the disease process. Few studies
investigating the effect of rat age on TNF- secretion have been
reported (4, 15). Serum levels of TNF- were low or nondetectable in
young (3-5 mo) and old (2 yr) Fischer 344 rats, and there were no
significant changes with age (15). Interestingly, we found that only
young SHR had measurable plasma TNF- levels. Also, organoid cultures
of aorta from old rats (30 mo) were capable of secreting TNF-,
whereas aorta from 10-mo-old rats were not (4). With respect to cardiac TNF-, our previous evidence (6) suggests that cardiac myocytes are
capable of secreting TNF-. Therefore, the normal loss of viable
cardiac muscle cells with age (1) may account for the observation that
there is a decrease in TNF- release from the left ventricle with
age, and this may be particularly relevant in hypertensive animals,
which demonstrate cardiac hypertrophy and, presumably, increased
fibrosis and cardiac myocyte death (40). Alternatively, during cardiac
decompensation, there may be an increase in receptor shedding, an
elaboration of neurohormones that may alter cAMP, and/or production of
counterregulatory cytokines, such as interleukin-10, which may
contribute to the decreased TNF- production with age.
Because we have previously shown that both type III and IV PDE isozyme
inhibitors inhibit TNF- release from young SD rat heart, we were
interested in determining whether the control of TNF- secretion by
PDE inhibitors changes with age or disease state. Previous studies have
shown no difference between IC50 values for amrinone inhibition of cAMP production in aortic smooth muscle from Wistar-Kyoto rats and SHR of unreported age (38). Also, the
percent inhibition of cardiac particulate and soluble type III PDE
produced by 1 µM milrinone was not different between sham-operated
rats and rats subjected to myocardial infarction, suggesting that
hypertension or the presence of heart failure, per se, does not
necessarily alter the overall ability of type III inhibitors to
increase intracellular cAMP. However, Smith et al. (39) have shown a
decrease in the expression of cardiac type III PDEs in a dog model of
heart failure, and the effectiveness of milrinone to alter papillary
muscle contractility was markedly decreased in 18-mo-old versus
2-mo-old rats (10), suggesting that age or the etiology of heart
failure may alter the effectiveness of PDE inhibitors on cardiac
TNF- secretion. In this study, the IC50 values for amrinone and
RO-201724 in 6-mo-old SD rats were similar to those reported by our
laboratory for 3-mo-old SD rats (6), and the
IC50 for amrinone approximates the
EC50 required to increase cardiac
index in humans (20 µM) (5). There were no significant effects of age
on either type III or type IV PDE IC50 values, and prolonged
hypertension, cardiac remodeling, or overt CHF did not alter the
potency or efficacy of the type III PDE inhibitor. A consistently
different profile was observed for type IV PDE inhibition, in which the
presence of hypertension and left ventricular hypertrophy variably
decreased efficacy without having marked effects on potency. The
relative lack of effect in SHR was particularly striking, and further
characterization of the PDE isoforms present in cardiac tissue, at both
the molecular expression and protein content levels, is warranted.
The mechanism of action of PDE inhibitors to inhibit secretion of
TNF- is thought to be mediated via alterations in intracellular cAMP
(36). The contribution of PDE III and IV to cAMP turnover may differ
with strain or disease state, or a compartmental shift may occur in the
cAMP pool, PDE, or cAMP-dependent protein kinases, allowing for
differential effectiveness of PDE inhibitors. Another possibility
exists in that inhibition of TNF- secretion by PDE inhibitors may
not be wholly dependent on changes in cAMP levels (as demonstrated for
other classes of TNF--inhibiting drugs) and that an additional
mechanism of action explains this difference in potency. Further
studies are necessary to delineate the mechanism(s) by which PDE
inhibitors inhibit cardiac TNF- secretion.
Because TNF- is secreted in equal amounts from cardiac tissue from
both SHR and SHHF rats at 6 and 12 mo of age, early expression of
TNF- in the myocardium may not serve as a marker to determine which
subjects will demonstrate progression of CHF. However, in a rodent
model of CHF, cardiac TNF- secretion is greater during florid
failure than in age-matched controls. It is known that SHHF rats are
desensitized to the effects of -adrenergic agonists (20), which may
result in decreased intramyocyte cAMP concentration and withdrawal of
cAMP-mediated TNF- suppression at later ages. Local production of
TNF- may contribute early (i.e., 6 mo of age) to cardiac remodeling
and later (i.e., 18 mo of age) to cardiac dysfunction, although cardiac
production does not contribute to measurable levels of TNF- in the
plasma of SHHF rats of either age. The physiological source of plasma
TNF- in 6-mo-old SHR requires further investigation. Studies should
be done examining myocardial TNF- receptor changes with age as well
as possible differences in TNF- biological effect with respect to
age and rat strain, particularly because of the fact that older rats
(15 mo) have diminished metabolic responses to exogenous TNF- (32).
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ACKNOWLEDGEMENTS |
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We gratefully acknowledge financial support from the Central Ohio Affiliate of the American Heart Association and National Heart, Lung, and Blood Institute Grant HL-48835.
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FOOTNOTES |
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Present address of M. R. Bergman: Veterans Affairs Medical Center, Cardiology Section, San Francisco, CA 94121.
Present address of R. H. Kao: Ohio State Biochemistry Program, The Ohio State Univ., Columbus, OH 43210.
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. §1734 solely to indicate this fact.
Address for reprint requests and other correspondence: B. J. Holycross, Dept. of Medical Biochemistry, The Ohio State Univ., 333 Hamilton Hall, 1645 Neil Ave., Columbus, OH 43210 (E-mail: bholycro{at}postbox.acs.ohio-state.edu).
Received 17 April 1998; accepted in final form 25 March 1999.
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REFERENCES |
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ABSTRACT
INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES
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|---|
1.
Anversa, P.,
T. Palackal,
E. H. Sonnenblick,
G. Olivetti,
L. G. Meggs,
and
J. M. Capasso.
Myocyte cell loss and myocyte cellular hyperplasia in the hypertrophied aging rat heart.
Circ. Res.
67:
871-885,
1990
2.
Armendariz-Borunda, J.,
K. Katayama,
and
J. M. Seyer.
Transcriptional mechanisms of type I collagen gene expression are differentially regulated by interleukin-1, tumor necrosis factor , and transforming growth factor in Ito cells.
J. Biol. Chem.
267:
14316-14321,
1992
3.
Bachetti, T.,
A. Corti,
A. Giordano,
and
R. Ferrari.
Tumor necrosis factor- in chronic heart failure.
In: Mechanisms of Heart Failure, edited by P. K. Singal,
I. M. C. Dixon,
R. E. Beamish,
and N. S. Dhalla. Boston, MA: Kluwer Academic, 1995, p. 3-8.
4.
Belmin, J.,
C. Bernard,
B. Corman,
R. Merval,
B. Esposito,
and
A. Tedgui.
Increased production of tumor necrosis factor and interleukin-6 by arterial wall of aged rats.
Am. J. Physiol.
268 (Heart Circ. Physiol. 37):
H2288-H2293,
1995
5.
Benet, L. Z.,
S. Oie,
and
J. B. Schwartz.
Design and optimization of dosage regimens; pharmacokinetic data.
In: Goodman and Gilman's The Pharmacological Basis of Therapeutics, edited by J. G. Hardman,
and L. E. Limbird. New York: McGraw Hill, 1996, p. 1707-1792.
6.
Bergman, M. R.,
and
B. J. Holycross.
Pharmacological modulation of myocardial tumor necrosis factor production by phosphodiesterase inhibitors.
J. Pharmacol. Exp. Ther.
279:
247-254,
1996
7.
Bienkowski, R. S.,
and
M. G. Gotkin.
Growth factor-mediated regulation of myocardial collagen gene expression.
In: Molecular Biology of Collagen Matrix in the Heart, edited by M. Eghbali-Webb. Austin, TX: Landes, 1995, p. 77-92.
8.
Bourassa, M. G.,
O. Gurne,
S. I. Bangdiwala,
J. K. Ghali,
J. B. Young,
M. Rousseau,
D. E. Johnstone,
and
S. Yusuf.
Natural history and patterns of current practice in heart failure.
J. Am. Coll. Cardiol.
22:
14A-19A,
1993.
9.
Burton, K.
Determination of DNA concentration with diphenylamine.
Methods Enzymol.
12B:
163-166,
1968.
10.
Canepari, M.,
B. Polla,
M. R. Gualea,
C. Zanardi,
and
C. Reggiani.
Age-dependent reduction of the response of rat cardiac muscle to the phosphodiesterase inhibitor milrinone.
Arch. Int. Physiol. Biochim. Biophys.
102:
265-269,
1994[Medline].
11.
Cohn, J. N.
The prevention of heart failure
a new agenda.
N. Engl. J. Med.
327:
725-727,
1992[Medline].
12.
Coito, A. J.,
J. Binder,
L. F. Brown,
M. de Sousa,
L. Van de Water,
and
J. W. Kupiec-Weglinski.
TNF- upregulates the expression of fibronectin in acutely rejecting rat cardiac allografts.
Transplant. Proc.
27:
463-465,
1995[Medline].
13.
Diaz, A.,
E. Munoz,
R. Johnston,
J. H. Korn,
and
S. A. Jimenez.
Regulation of human lung fibroblast 1(I) procollagen gene expression by tumor necrosis factor , interleukin-1, and prostaglandin E2.
J. Biol. Chem.
268:
10364-10371,
1993
14.
Ferrari, R.,
T. Bachetti,
R. Confortini,
C. Opasich,
O. Febo,
A. Corti,
G. Cassani,
and
O. Visioli.
Tumor necrosis factor soluble receptors in patients with various degrees of congestive heart failure.
Circulation
92:
1479-1486,
1995
15.
Foster, K. D.,
C. A. Conn,
and
M. J. Kluger.
Fever, tumor necrosis factor, and interleukin-6 in young, mature, and aged Fischer 344 rats.
Am. J. Physiol.
262 (Regulatory Integrative Comp. Physiol. 31):
R211-R215,
1992
16.
Gerdes, A. M.,
T. Onodera,
X. Wang,
and
S. A. McCune.
Myocyte remodeling during the progression to failure in rats with hypertension.
Hypertension
28:
609-614,
1996
17.
Giroir, B. P.,
and
B. Beutler.
Effect of amrinone on tumor necrosis factor production in endotoxic shock.
Circ. Shock
36:
200-207,
1992[Medline].
18.
Giroir, B. P.,
J. H. Johnson,
T. Brown,
G. L. Allen,
and
B. Beutler.
The tissue distribution of tumor necrosis factor biosynthesis during endotoxemia.
J. Clin. Invest.
90:
693-698,
1992.
19.
Haas, G. J.,
S. A. McCune,
D. M. Brown,
and
R. J. Cody.
Echocardiographic characterization of left ventricular adaptation in a genetically determined heart failure rat model.
Am. Heart J.
130:
806-811,
1995[Medline].
20.
Hohl, C. M.,
B. Hu,
R. H. Fertel,
J. C. Russell,
S. A. McCune,
and
R. A. Altschuld.
Effects of obesity and hypertension on ventricular myocytes: comparison of cells from adult SHHF/Mcc-cp and JCR:LA-cp rats.
Cardiovasc. Res.
27:
238-242,
1993
21.
Holobaugh, P. A.,
and
D. C. McChesney.
Effect of anticoagulants and heat on the detection of tumor necrosis factor in murine blood.
J. Immunol. Methods
135:
95-99,
1990[Medline].
22.
Holycross, B. J.,
B. M. Summers,
R. B. Dunn,
and
S. A. McCune.
Plasma renin activity in heart failure prone (SHHF-Mcc-facp) rats.
Am. J. Physiol.
273 (Heart Circ. Physiol. 42):
H228-H233,
1997
23.
Kapadia, S. R.,
H. Oral,
J. Lee,
M. Nakano,
G. E. Taffet,
and
D. L. Mann.
Hemodynamic regulation of tumor necrosis factor-alpha gene and protein expression in adult feline myocardium.
Circ. Res.
81:
187-195,
1997
24.
Klein, R. M.,
B. K. MacGillivray,
and
J. C. McKenzie.
Markers of cardiac hypertrophy.
Ann. NY Acad. Sci.
752:
210-217,
1995[Medline].
25.
Levine, B.,
J. Kalman,
L. Mayer,
H. M. Fillit,
and
M. Packer.
Elevated circulating levels of tumor necrosis factor in severe chronic heart failure.
N. Engl. J. Med.
323:
236-241,
1990[Abstract].
26.
Lowry, O. H.,
N. J. Rosebrough,
A. L. Farr,
and
R. J. Randall.
Protein measurement with the Folin phenol reagent.
J. Biol. Chem.
193:
265-275,
1951
27.
Matthews, N.,
and
M. L. Neale.
Cytotoxicity assays for tumour necrosis factor and lymphotoxin.
In: Lymphokines and Interferons. A Practical Approach, edited by M. J. Clemens,
A. G. Morris,
and A. J. H. Gearing. Washington, D.C.: IRL, 1987, p. 221-225.
28.
McCune, S. A.,
P. B. Baker,
and
H. F. Stills.
SHHF/Mcc-cp rat: model of obesity, non-insulin-dependent diabetes, and congestive heart failure.
ILAR News
32:
23-27,
1990.
29.
McCune, S. A.,
S. Park,
M. J. Radin,
and
R. R. Jurin.
SHHF/Mcc-facp rat model: a genetic model of congestive heart failure.
In: Mechanisms of Heart Failure, edited by P. K. Singal,
I. M. C. Dixon,
R. E. Beamish,
and N. S. Dhalla. Boston, MA: Kluwer Academic, 1995, p. 91-106.
30.
McMurray, J.,
I. Abdullah,
H. J. Dargie,
and
D. Shapiro.
Increased concentrations of tumour necrosis factor in "cachectic" patients with severe chronic heart failure.
Br. Heart J.
66:
356-358,
1991
31.
Molnar-Kimber, K.,
L. Yonno,
R. Heaslip,
and
B. Weichman.
Modulation of TNF and IL-1 from endotoxin-stimulated monocytes by selective PDE isozyme inhibitors.
Agents Actions
39:
C77-C79,
1993.
32.
Mondon, C. E.,
and
H. F. Starnes.
Differential metabolic responses to tumor necrosis factor with increase in age.
Metabolism
41:
970-981,
1992[Medline].
33.
Natanson, C.,
P. W. Eichenholz,
R. L. Danner,
P. Q. Eichacker,
W. D. Hoffman,
G. C. Kuo,
S. M. Banks,
T. J. MacVittie,
and
J. E. Parrillo.
Endotoxin and tumor necrosis factor challenges in dogs simulate the cardiovascular profile of human septic shock.
J. Exp. Med.
169:
823-832,
1989
34.
Oral, H.,
S. Kapadia,
M. Nakano,
G. Torre-Amione,
J. Lee,
D. Lee-Jackson,
J. B. Young,
and
D. L. Mann.
Tumor necrosis factor- and the failing human heart.
Clin. Cardiol.
18:
IV-20-IV-27,
1995.
35.
Packer, M.
Is tumor necrosis factor an important neurohormonal mechanism in chronic heart failure?
Circulation
92:
1379-1382,
1995
36.
Semmler, J.,
U. Gebert,
T. Eisenhut,
J. Moeller,
M. M. Schonharting,
A. Allera,
and
S. Endres.
Xanthine derivatives: comparison between suppression of tumour necrosis factor- production and inhibition of cAMP phosphodiesterase activity.
Immunology
78:
520-525,
1993[Medline].
37.
Semmler, J.,
H. Wachtel,
and
S. Endres.
The specific type IV phosphodiesterase inhibitor rolipram suppresses tumor necrosis factor- production by human mononuclear cells.
Int. J. Immunopharmacol.
15:
409-413,
1993[Medline].
38.
Silver, P. J.,
R. J. Gordon,
R. A. Buchholz,
R. L. Dundore,
E. W. Ferguson,
A. L. Harris,
and
E. D. Pagani.
Comparative studies on cyclic nucleotide phosphodiesterases and inhibitors in experimental models of hypertension, congestive heart failure, and allergic asthma.
Adv. Second Messenger Phosphoprotein Res.
25:
341-351,
1992[Medline].
39.
Smith, C. J.,
D. Sun,
C. Hoegler,
G. Zhao,
X. Xu,
and
R. A. Moggio.
Reduced gene expression of the cyclic GMP-inhibited, cyclic AMP phosphodiesterase III in canine heart failure (Abstract).
Circulation
90:
I-425,
1994.
40.
Thiedemann, K. U.,
C. Holubarsch,
I. Medugorac,
and
R. Jacob.
Connective tissue content and myocardial stiffness in pressure overload hypertrophy. A combined study of morphologic, morphometric, biochemical and mechanical parameters.
Basic Res. Cardiol.
78:
140-155,
1983[Medline].
41.
Torre-Amione, G.,
S. Kapadia,
C. Benedict,
H. Oral,
J. B. Young,
and
D. L. Mann.
Proinflammatory cytokine levels in patients with depressed left ventricular ejection fraction: a report from the studies of left ventricular dysfunction (SOLVD).
J. Am. Coll. Cardiol.
27:
1201-1206,
1996[Abstract].
42.
Torre-Amione, G.,
S. Kapadia,
J. Lee,
J. B. Durand,
R. D. Bies,
J. B. Young,
and
D. L. Mann.
Tumor necrosis factor- and tumor necrosis factor receptors in the failing human heart.
Circulation
93:
704-711,
1996
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