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 283: H2644-H2649, 2002. First published July 26, 2002; doi:10.1152/ajpheart.00369.2002
0363-6135/02 $5.00
This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow All Versions of this Article:
283/6/H2644    most recent
00369.2002v1
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 (5)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Hermenegildo, C.
Right arrow Articles by Cano, A.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Hermenegildo, C.
Right arrow Articles by Cano, A.
Vol. 283, Issue 6, H2644-H2649, December 2002

Estradiol reduces F2alpha -isoprostane production in cultured human endothelial cells

Carlos Hermenegildo1,2, María Cinta García-Martínez3, Juan J. Tarín4, and Antonio Cano3

1 Research Unit, Hospital Clinic Universitari de Valencia and Departments of 2 Physiology, 3 Paediatrics, Obstetrics and Gynaecology, and 4 Functional Biology and Physical Anthropology, University of Valencia, E-46010 Valencia, Spain


    ABSTRACT
TOP
ABSTRACT
INTRODUCTION
MATERIALS AND METHODS
RESULTS
DISCUSSION
REFERENCES

Free radical-generated F2alpha -isoprostanes are a group of compounds with vasoconstrictor properties. To investigate whether estradiol exerts antioxidant actions modifying F2alpha -isoprostane production, cultured human umbilical vein endothelial cells were exposed to estradiol and other compounds and F2alpha -isoprostanes were measured in culture medium. Exposure to 1 and 10 nM estradiol for 24 h reduced F2alpha -isoprostane production by 36 and 49%, respectively (P < 0.001 vs. control). Exposure to antiestrogens alone (ICI-182780 or EM-652) slightly reduced F2alpha -isoprostanes (P < 0.05 vs. control), but much less than exposure to estradiol (P < 0.05). ICI-182780 reversed the estradiol-induced reduction of F2alpha -isoprostane concentration (P < 0.05). Along with time-course analysis, these results suggest that estradiol effects were mediated through estrogen receptor-dependent and -independent mechanisms. Progestogens alone (progesterone or medroxyprogesterone acetate) did not modify F2alpha -isoprostane production at any of the tested concentrations (1, 10, and 100 nM). Progesterone completely reversed estradiol-induced reduction of F2alpha -isoprostane production (P < 0.05 vs. control and estradiol), but medroxyprogesterone acetate did not (P < 0.05 vs. control).

antioxidant; endothelium; estrogens; hormone replacement therapy; isoprostanes


    INTRODUCTION
TOP
ABSTRACT
INTRODUCTION
MATERIALS AND METHODS
RESULTS
DISCUSSION
REFERENCES

ESTRADIOL (E2) has been proposed to exert antioxidant effects in in vitro models as well as in many biological systems (24), a property that has been related to the beneficial effects of estrogens on cardiovascular parameters (18). High, nonphysiological E2 concentrations inhibit in vitro low-density lipoprotein (LDL) oxidation, a parameter that has been related to progression of atherosclerosis (1, 20). E2 has been reported to diminish LDL oxidation in postmenopausal women in some studies (29, 38), but not in others (9, 30). Progestogens usually accompany E2 exposure. The effect of such coexposure on the antioxidant action of E2 is unclear; the effects of progestogens on LDL oxidation have been refuted (23) and confirmed (42).

Classically, the antioxidant effects of E2 have been ascribed to the aromatic hydroxyphenol structure of the A ring (24). Nevertheless, an antioxidant action mediated by estrogen receptors (ER) cannot be completely ruled out.

E2 acts directly on the endothelium and influences the vascular function and reactivity. Among other mechanisms, E2 enhances endothelial production of vasodilator compounds, such as nitric oxide and prostacyclin, and reduces production of vasoconstrictors, such as endothelin-1 and thromboxane A2 (18). Moreover, E2 prevents oxidative stress-induced apoptosis of endothelial cells (34). The measurement of E2 antioxidant capacity could be relevant to an understanding of the vascular actions of the hormone, because the endothelium is an important source of beneficial and deleterious free radicals that have been involved in numerous physiological pathways (5, 35).

Recently, F2alpha -isoprostanes have been recognized as a stable, good biomarker of in vivo oxidative stress (4, 27). F2alpha -isoprostanes are prostaglandin-like products of nonenzymatic, free radical-catalyzed peroxidation of arachidonic acid (4), which has been correlated with conditions of increased oxidation. In humans, for instance, elevated plasma F2alpha -isoprostane levels have been found in several conditions associated with enhanced oxidative stress, such as chronic cigarette smoking (21), cystic fibrosis (2), and long-term hemodialysis (6). Furthermore, increased F2alpha -isoprostane levels have been found in human atherosclerotic lesions (25). As a result, recently, there has been great interest in the cardiovascular actions of F2alpha -isoprostanes (26, 41).

Under the assumption that F2alpha -isoprostane production could be a good index for assessing the antioxidant effects of E2 in endothelial cells as well as an important biomarker of its vascular actions, the aims of our work were 1) to study the effects of physiological and near-physiological concentrations of E2 on F2alpha -isoprostane production by endothelial cells, 2) to determine whether this action is mediated by ER, and 3) to describe the role of progestogens, with or without E2, on F2alpha -isoprostane production.


    MATERIALS AND METHODS
TOP
ABSTRACT
INTRODUCTION
MATERIALS AND METHODS
RESULTS
DISCUSSION
REFERENCES

Materials

Culture flasks and plates were obtained from Orange Scientific (Waterloo, Belgium). ICI-182780 was purchased from Tocris Cookson (Bristol, UK). EM-652 was a generous gift from Dr. Labrie (Endorecherche, Quebec, Canada). All other materials were purchased from Sigma Chemical (St. Louis, MO).

Cell Culture

Primary human umbilical vein endothelial cells (HUVECs) from male or female newborns were isolated by collagenase treatment of human umbilical veins as described elsewhere (10). Briefly, HUVECs were cultured in 25-cm2 flasks in human endothelial cell-specific medium (EBM-2, Clonetics, BioWhittaker, Walkersville, MD) supplemented with EGM-2 (Clonetics) at the manufacturer's recommended concentration and maintained in a cell culture incubator at 37°C in a 5% CO2 atmosphere.

Cells were identified as endothelial by their characteristic cobblestone morphology and the presence of factor VIII antigen (von Willebrand factor) by immunocytochemistry using a specific antibody (sc-8068, Santa Cruz Biotechnology, Santa Cruz, CA).

Experimental Design

Cells from passages 4-6 were seeded onto 24-well plates. At 75% confluence, culture medium was removed, and cells were maintained for 24 h in phenol red-free medium 199 (GIBCO-BRL, Life Technologies, Paisley, UK) supplemented with 20% charcoal-dextran-treated, heat-inactivated fetal bovine serum (GIBCO-BRL). For exposure to different treatments, culture medium was eliminated, and immediately 500 µl of phenol red-free medium 199 containing the desired treatments were added to each well.

After different times of incubation, culture medium was removed and stored at -20°C until assayed. Culture wells were then washed with phosphate-buffered saline, and cells were collected in 100 µl of 0.5 N NaOH for protein determination.

Analytic Methods

F2alpha -isoprostane determination. To measure total (free + esterified) F2alpha -isoprostanes, 400 µl of culture medium were deproteinized with 800 µl of absolute ethanol and then subjected to alkaline hydrolysis with 15% KOH for 1 h at 40°C to transform the esterified isoprostane to free isoprostane. F2alpha -isoprostanes were purified by using specific F2alpha -isoprostane affinity columns according to the manufacturer's instructions (Cayman Chemical, Ann Arbor, MI). Briefly, samples were diluted 1:5 with 0.1 M phosphate buffer, applied to the column, and eluted with 95% ethanol. After evaporation of ethanol to dryness by vacuum centrifugation, samples were immediately dissolved in 100 µl of enzyme immunoassay (EIA) buffer and assayed in duplicate by using a commercial F2alpha -isoprostane EIA kit (Cayman Chemical). The range of the standard curve was 3.9-500 pg/ml. The samples were read at 415 nm in a 96-well Benchmark Microplate reader (Bio-Rad Laboratories, Hercules, CA). Plasma recovery was >90%, with a variance of <20%. The intra- and interassay coefficients of variation for this method were <10%.

Protein measurement. Protein concentration in culture wells was measured by the modified Lowry procedure (16).

Statistical Analysis

Values are means ± SE. Repeated-measures ANOVA was applied for comparisons of means, and then Student's t-test was performed. P <=  0.05 was considered significant.


    RESULTS
TOP
ABSTRACT
INTRODUCTION
MATERIALS AND METHODS
RESULTS
DISCUSSION
REFERENCES

To investigate the effects of E2 on F2alpha -isoprostane production, endothelial cells were exposed to three different E2 concentrations for up to 48 h. The time course of control and E2-induced effects is presented in Fig. 1. There was a sustained, spontaneous production of F2alpha -isoprostane in control, nonstimulated endothelial cells (exposed only to vehicle) for 48 h. Control F2alpha -isoprostane concentrations in culture medium were significantly higher at 16, 24, and 48 h than at shorter incubation times. Exposure to different concentrations of E2 for <= 8 h did not modify F2alpha -isoprostane production. Exposure to 1 nM E2 decreased F2alpha -isoprostane production only after 24 h, whereas 10 nM E2-induced reduction of F2alpha -isoprostane production was significant after 16 h.


View larger version (21K):
[in this window]
[in a new window]
  		Fig. 1.   Time course of estradiol effects on spontaneous production of F2alpha -isoprostane by cultured endothelial cells. Cultured human umbilical vein endothelial cells (HUVECs) were exposed to different concentrations of estradiol for 1-48 h, culture medium was collected, and F2alpha -isoprostane concentration was measured. Values are means ± SE of 4-6 duplicate determinations corresponding to 2 different experiments performed in cells from different cultures. *P < 0.05 vs. control values at 0, 1, 4, and 8 h; dagger P < 0.01 vs. control values at the same time point.

Therefore, the remaining experiments were performed at 24 h of incubation with different compounds. F2alpha -isoprostane formation in control endothelial cells was 112 ± 13 pg/mg protein in 24 h. Exposure of endothelial cells to 1 and 10 nM E2 for 24 h decreased F2alpha -isoprostane production by 36 and 49%, respectively (P < 0.001 for both values).

The time course of E2 effects (Fig. 1) suggested a genomic action of E2. To test whether this effect was mediated through ER activation, endothelial cells were exposed to ICI-182780 or EM-652, two compounds with antiestrogenic activity (Fig. 2). Exposure to 10 µM ICI-182780 alone slightly reduced F2alpha -isoprostane content in culture medium (P < 0.05 vs. control), but the reduction was much less than that observed with exposure to E2 (P < 0.05 vs. E2 values). When administered along with 1 nM E2, ICI-182780 reversed the E2-induced reduction of F2alpha -isoprostane concentration (P < 0.05 vs. E2 values) to the same levels as ICI-182780 alone. Administration of EM-652 alone also reduced F2alpha -isoprostane content in culture medium (P < 0.05 vs. control), but the reduction was less than that observed with administration of E2 (P < 0.05 vs. E2 values).


View larger version (31K):
[in this window]
[in a new window]
  		Fig. 2.   Effect of antiestrogens on estradiol-induced reduction of F2alpha -isoprostane production by cultured endothelial cells. Cultured HUVECs were exposed to 1 nM estradiol, 10 µM ICI-182780, and/or 10 µM EM-652 for 24 h, culture medium was collected, and F2alpha -isoprostane concentration was measured. Values are means ± SE of 7-14 duplicate determinations corresponding to 3-4 different experiments performed in cells from different cultures. Average control value for all experiments was 106 ± 9 pg/mg protein (range 87-165 pg/mg protein). *P < 0.05 vs. control values; dagger P < 0.05 vs. estradiol values.

To test the effects of progestogens, endothelial cells were exposed to three different concentrations of progesterone and medroxyprogesterone acetate. None of the tested compounds, at any concentration (1, 10, and 100 nM) modified the endothelial cell production of F2alpha -isoprostanes (Fig. 3). When used in combination with E2, however, each progestogen behaved differently (Fig. 4). Thus progesterone almost completely reversed the E2-induced reduction of F2alpha -isoprostane production (P < 0.05 vs. control values and vs. E2 values). Instead, medroxyprogesterone acetate did conserve the effect achieved by E2 alone (P < 0.05 vs. control values).


View larger version (33K):
[in this window]
[in a new window]
  		Fig. 3.   Lack of effect of progestins on spontaneous production of F2alpha -isoprostane by cultured endothelial cells. Cultured HUVECs were exposed to different concentrations of progesterone or medroxyprogesterone for 24 h, culture medium was collected, and F2alpha -isoprostane concentration was measured. Values are means ± SE of 5-9 duplicate determinations corresponding to 2-3 different experiments performed in cells from different cultures. Average control value for all experiments was 123 ± 11 pg/mg protein (range 87-161 pg/mg protein).



View larger version (26K):
[in this window]
[in a new window]
  		Fig. 4.   Effect of combined exposure to estradiol and progesterone or medroxyprogesterone on F2alpha -isoprostane production by cultured endothelial cells. Cultured HUVECs were exposed to 1 nM estradiol, 10 nM progesterone, and/or 10 nM medroxyprogesterone for 24 h, culture medium was collected, and F2alpha -isoprostane concentration was measured. Values are means ± SE of 5-11 duplicate determinations corresponding to 3-4 different experiments performed in cells from different cultures. Average control value for all experiments was 117 ± 12 pg/mg protein (range 78-161 pg/mg protein). *P < 0.05 vs. control values; dagger P < 0.05 vs. estradiol values.


    DISCUSSION
TOP
ABSTRACT
INTRODUCTION
MATERIALS AND METHODS
RESULTS
DISCUSSION
REFERENCES

Our results clearly indicate that physiological (1 nM) and near-physiological (10 nM) E2 concentrations caused a dose-dependent decrease in spontaneous endothelial cell production of F2alpha -isoprostanes. This finding is important, because the majority of in vitro studies required supraphysiological, micromolar concentrations (1,000-fold higher than the average physiological level) to reveal an antioxidant action of estrogens (1, 20).

Endothelial cells are a major target of oxidative stress and a critical element in the pathophysiology of several diseases, including hypercholesterolemia, atherosclerosis, hypertension, and heart failure. F2alpha -isoprostane reduction confirms an E2-induced impairment of oxidative stress and supports a role for the hormone in maintaining the integrity of endothelial cells.

Time-course analysis, in which E2 effects are evident only after 16-24 h (10 and 1 nM E2, respectively), suggests an ER-mediated, genomic effect. The implication that ER have a role in the antioxidant effects of E2 has been refuted by using 17alpha -estradiol, an E2 isomer that has antioxidant activity but cannot bind to ER (20), or by using ER-free systems (1, 33).

Two antiestrogens, ICI-128780 and EM-652, were used to study the role of ER. Both antiestrogens are competitive inhibitors of the E2-ER relationship, although some differences in their mechanism of action have been reported. For instance, ICI-182780 is able to bind to ER in the cell cytoplasm, diminishing ER transport to the nucleus, and also has been reported to inhibit aromatase activity (7).

Administration of both antiestrogens at doses that are adequate to ensure ER antagonism (11, 15) partially abolished the antioxidant effect of E2. Taken together, data from Figs. 1 and 2 imply that E2 antioxidant actions are, at least in part, genomic actions mediated through ER activation. The mechanism by which this occurs is unknown, but E2 could act, at physiological doses, as an antioxidant at the genomic level in endothelial cells by inhibiting NADPH oxidase expression, an important source of free radicals (36).

Nevertheless, because a tendency to decrease F2alpha -isoprostane concentration is evident from the first time point (Fig. 1), rapid, nongenomic actions mediated through ER should not be completely ruled out. Among the signaling pathways activated by E2 are those mediated by phosphatidylinositol-3-hydroxykinase Akt, Src tyrosine kinase, and mitogen-activated protein kinases (reviewed in Ref. 19). These pathways increase endothelial nitric oxide synthase activity and nitric oxide production (19), which in turn modulate production of free radicals, mainly superoxide anion and hydrogen peroxide (35).

Interestingly, antiestrogens partially decreased F2alpha -isoprostane production by endothelial cells. In agreement with our data, ICI-182780 has recently been reported to indirectly exert antioxidant actions by inducing the antioxidant enzyme quinone reductase in breast cancer cells (12) or by decreasing the mitogenic response to lysophosphatidylcholine in vascular smooth muscle cells (40). Also, both antiestrogens have revealed antioxidant activity against in vitro copper-induced LDL oxidation (8).

Progesterone and medroxyprogesterone acetate had a neutral effect on endothelial F2alpha -isoprostane production. This is in accordance with most of the in vitro and in vivo available studies (32) but is in contrast to a recent report, where micromolar concentrations of medroxyprogesterone acetate exerted a stronger prooxidant action (42). It is then possible that the prooxidant effect of progestogens, if real, is detected only at concentrations that exceed physiological levels.

Interestingly, a different effect was observed when cells were exposed to E2 along with progestogen. Progesterone, at doses within physiological levels, reversed the effect of E2, but medroxyprogesterone acetate did not. The effect of the association of progestogen with E2 on cardiovascular risk factors remains debatable, with authors supporting a neutral action (13), or even a prejudicial effect, for medroxyprogesterone acetate (37). Previous studies support the differential effect reported in the present work. For instance, progesterone opposes the antioxidant actions of estrogen on plasma LDL oxidation in primates (17), whereas medroxyprogesterone acetate, used in hormone replacement therapy, did not counteract the effect of E2 on LDL oxidation (23).

Interactions of physiological concentrations of progesterone and E2 may be of interest in premenopausal, pregnant women and postmenopausal women receiving hormone replacement therapy for cyclic variations in progesterone concentrations. Such variations could significantly modify or mask the effects of E2, and careful time-dependent studies should be done. Among other possibilities, progesterone downregulates ER and also may have direct progesterone receptor-mediated effects that oppose favorable effects of estrogen (31).

The initial criticism against the F2alpha -isoprostane measurement by EIA has been eliminated by the use of specific columns to adequately prepare the samples (28) and by the improvement of the commercially available kits, which actually exhibit a very good correlation with other analytic methods, such as gas chromatography-mass spectrometry (3, 39).

In addition to diminishing oxidative stress, F2alpha -isoprostane reduction has its own impact in vascular function, because F2alpha -isoprostanes are powerful vasoconstrictors in vivo and in vitro (22, 26) and potent stimulants of vascular smooth muscle cells (14). Also, F2alpha -isoprostanes exert different effects on endothelial cell function: stimulation of cell proliferation and enhancement of expression and release of endothelin-1 (41). The majority, if not all, of these vasoconstrictor actions are mediated through activation of thromboxane A2 receptors or other closely related receptors (26, 41).

In conclusion, our results demonstrate an antioxidant effect of physiological concentrations of E2, probably mediated by genomic, ER-mediated mechanisms of action. Progesterone, but not medroxyprogesterone acetate, neutralizes the effects of E2. Reduction of F2alpha -isoprostane production reveals new insights into the molecular mechanisms involved in the beneficial effects of estrogens on cardiovascular function.


    ACKNOWLEDGEMENTS

The authors are indebted to R. Aliaga and E. Calap for excellent technical assistance.


    FOOTNOTES

This study was supported by Spanish Ministry of Education and Culture Grant 1FD97-1035-C02-01 and European Union Grants 00/0960 and 01/0917 from the Spanish Ministry of Healthy and GV01/69 from the Oficina de Ciencia y Tecnología (Generalitat Valenciana).

Address for reprint requests and other correspondence: C. Hermenegildo, Depts. of Paediatrics and Obstetrics and Gynaecology, Faculty of Medicine and Dentistry, Avda. Blasco Ibañez 17, E-46010 Valencia, Spain (E-mail: carlos.hermenegildo{at}uv.es).

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.

July 26, 2002;10.1152/ajpheart.00369.2002

Received 29 April 2002; accepted in final form 24 July 2002.


    REFERENCES
TOP
ABSTRACT
INTRODUCTION
MATERIALS AND METHODS
RESULTS
DISCUSSION
REFERENCES

1.   Arteaga, E, Rojas A, Villaseca P, Bianchi M, Arteaga A, and Duran D. In vitro effect of estradiol, progesterone, testosterone, and of combined estradiol/progestins on low-density lipoprotein (LDL) oxidation in postmenopausal women. Menopause 5: 16-23, 1998[ISI][Medline].

2.   Collins, CE, Quaggiotto P, Wood L, O'Loughlin EV, Henry RL, and Garg ML. Elevated plasma levels of F2alpha -isoprostane in cystic fibrosis. Lipids 34: 551-556, 1999[ISI][Medline].

3.   Devaraj, S, Hirany SV, Burk RF, and Jialal I. Divergence between LDL oxidative susceptibility and urinary F2-isoprostanes as measures of oxidative stress in type 2 diabetes. Clin Chem 47: 1974-1979, 2001[Abstract/Free Full Text].

4.   De Zwart, LL, Meerman JH, Commandeur JN, and Vermeulen NP. Biomarkers of free radical damage: applications in experimental animals and in humans. Free Radic Biol Med 26: 202-226, 1999[ISI][Medline].

5.   Finkel, T. Oxygen radicals and signaling. Curr Opin Cell Biol 10: 248-253, 1998[ISI][Medline].

6.   Handelman, GJ, Walter MF, Adhikarla R, Gross J, Dallal GE, Levin NW, and Blumberg JB. Elevated plasma F2-isoprostanes in patients on long-term hemodialysis. Kidney Int 59: 1960-1966, 2001[ISI][Medline].

7.   Hermenegildo, C, and Cano A. Pure anti-oestrogens. Hum Reprod Update 6: 237-243, 2000[Abstract/Free Full Text].

8.  Hermenegildo C, Garcia-Martinez MC, Tarin JJ, and Cano A. Inhibition of LDL oxidation by the pure antiestrogens ICI-182780 and EM-652 (SCH 57068). Menopause. In press.

9.   Hermenegildo, C, Garcia-Martinez MC, Tarin JJ, Llacer A, and Cano A. The effect of oral hormone replacement therapy on lipoprotein profile, resistance of LDL to oxidation and LDL particle size. Maturitas 38: 287-295, 2001[ISI][Medline].

10.   Jaffe, EA, Nachman RL, Becker CG, and Minick CR. Culture of human endothelial cells derived from umbilical veins. Identification by morphologic and immunologic criteria. J Clin Invest 52: 2745-2756, 1973[ISI][Medline].

11.   Jayachandran, M, Hayashi T, Sumi D, Iguchi A, and Miller VM. Temporal effects of 17beta -estradiol on caveolin-1 mRNA and protein in bovine aortic endothelial cells. Am J Physiol Heart Circ Physiol 281: H1327-H1333, 2001[Abstract/Free Full Text].

12.   Katzenellenbogen, BS, Choi I, Delage-Mourroux R, Ediger TR, Martini PG, Montano M, Sun J, Weis K, and Katzenellenbogen JA. Molecular mechanisms of estrogen action: selective ligands and receptor pharmacology. J Steroid Biochem Mol Biol 74: 279-285, 2000[ISI][Medline].

13.   Koh, KK, Jin DK, Yang SH, Lee SK, Hwang HY, Kang MH, Kim W, Kim DS, Choi IS, and Shin EK. Vascular effects of synthetic or natural progestogen combined with conjugated equine estrogen in healthy postmenopausal women. Circulation 103: 1961-1966, 2001[Abstract/Free Full Text].

14.   Kromer, BM, and Tippins JR. Coronary artery constriction by the isoprostane 8-epiprostaglandin F2alpha . Br J Pharmacol 119: 1276-1280, 1996[ISI][Medline].

15.   Labrie, F, Labrie C, Belanger A, Simard J, Gauthier S, Luu-The V, Merand Y, Giguere V, Candas B, Luo S, Martel C, Singh SM, Fournier M, Coquet A, Richard V, Charbonneau R, Charpenet G, Tremblay A, Tremblay G, Cusan L, and Veilleux R. EM-652 (SCH 57068), a third-generation SERM acting as pure antiestrogen in the mammary gland and endometrium. J Steroid Biochem Mol Biol 69: 51-84, 1999[ISI][Medline].

16.   Lowry, OH, Rosebrough NJ, Farr AL, and Randall RJ. Protein measurement with the Folin phenol reagent. J Biol Chem 196: 265-275, 1951[ISI].

17.   McKinney, KA, Duell PB, Wheaton DL, Hess DL, Patton PE, Spies HG, and Burry KA. Differential effects of subcutaneous estrogen and progesterone on low-density lipoprotein size and susceptibility to oxidation in postmenopausal rhesus monkeys. Fertil Steril 68: 525-530, 1997[ISI][Medline].

18.   Mendelsohn, ME, and Karas RH. The protective effects of estrogen on the cardiovascular system. N Engl J Med 340: 1801-1811, 1999[Free Full Text].

19.   Moggs, JG, and Orphanides G. Estrogen receptors: orchestrators of pleiotropic cellular responses. EMBO Rep 2: 775-781, 2001[ISI][Medline].

20.   Moosmann, B, and Behl C. The antioxidant neuroprotective effects of estrogens and phenolic compounds are independent from their estrogenic properties. Proc Natl Acad Sci USA 96: 8867-8872, 1999[Abstract/Free Full Text].

21.   Morrow, JD, Frei B, Longmire AW, Gaziano JM, Lynch SM, Shyr Y, Strauss WE, Oates JA, and Roberts LJ. Increase in circulating products of lipid peroxidation (F2-isoprostanes) in smokers. Smoking as a cause of oxidative damage. N Engl J Med 332: 1198-1203, 1995[Abstract/Free Full Text].

22.   Morrow, JD, Minton TA, Mukundan CR, Campbell MD, Zackert WE, Daniel VC, Badr KF, Blair IA, and Roberts LJ. Free radical-induced generation of isoprostanes in vivo. Evidence for the formation of D-ring and E-ring isoprostanes. J Biol Chem 269: 4317-4326, 1994[Abstract/Free Full Text].

23.   Mueck, AO, Seeger H, and Lippert TH. Estradiol inhibits LDL oxidation: do the progestins medroxyprogesterone acetate and norethisterone acetate influence this effect? Clin Exp Obstet Gynecol 25: 26-28, 1998[Medline].

24.   Nathan, L, and Chaudhuri G. Antioxidant and prooxidant actions of estrogens: potential physiological and clinical implications. Semin Reprod Endocrinol 16: 309-314, 1998[ISI][Medline].

25.   Oguogho, A, Kritz H, Wagner O, and Sinzinger H. 6-Oxo-PGF1alpha and 8-epi-PGF2alpha in the arterial wall layers of various species: a comparison between intact and atherosclerotic areas. Prostaglandins Leukot Essent Fatty Acids 64: 167-171, 2001[ISI][Medline].

26.   Oliveira, L, Stallwood NA, and Crankshaw DJ. Effects of some isoprostanes on the human umbilical artery in vitro. Br J Pharmacol 129: 509-514, 2000[ISI][Medline].

27.   Pratico, D. F2-isoprostanes: sensitive and specific non-invasive indices of lipid peroxidation in vivo. Atherosclerosis 147: 1-10, 1999[ISI][Medline].

28.   Proudfoot, J, Barden A, Mori TA, Burke V, Croft KD, Beilin LJ, and Puddey IB. Measurement of urinary F2-isoprostanes as markers of in vivo lipid peroxidation---a comparison of enzyme immunoassay with gas chromatography/mass spectrometry. Anal Biochem 272: 209-215, 1999[ISI][Medline].

29.   Sack, MN, Rader DJ, and Cannon RO. Oestrogen and inhibition of oxidation of low-density lipoproteins in postmenopausal women. Lancet 343: 269-270, 1994[ISI][Medline].

30.   Santanam, N, Shern-Brewer R, McClatchey R, Castellano PZ, Murphy AA, Voelkel S, and Parthasarathy S. Estradiol as an antioxidant: incompatible with its physiological concentrations and function. J Lipid Res 39: 2111-2118, 1998[Abstract/Free Full Text].

31.   Sarrel, PM. The differential effects of oestrogens and progestins on vascular tone. Hum Reprod Update 5: 205-209, 1999[Abstract/Free Full Text].

32.   Schroder, J, Doren M, Schneider B, and Oettel M. Are the antioxidative effects of 17beta -estradiol modified by concomitant administration of a progestin? Maturitas 25: 133-139, 1996[ISI][Medline].

33.   Shwaery, GT, Vita JA, and Keaney JFJ Antioxidant protection of LDL by physiologic concentrations of estrogens is specific for 17beta -estradiol. Atherosclerosis 138: 255-262, 1998[ISI][Medline].

34.   Sudoh, N, Toba K, Akishita M, Ako J, Hashimoto M, Iijima K, Kim S, Liang YQ, Ohike Y, Watanabe T, Yamazaki I, Yoshizumi M, Eto M, and Ouchi Y. Estrogen prevents oxidative stress-induced endothelial cell apoptosis in rats. Circulation 103: 724-729, 2001[Abstract/Free Full Text].

35.   Vanhoutte, PM. Endothelium-derived free radicals: for worse and for better. J Clin Invest 107: 23-25, 2001[ISI][Medline].

36.   Wagner, AH, Schroeter MR, and Hecker M. 17beta -Estradiol inhibition of NADPH oxidase expression in human endothelial cells. FASEB J 15: 2121-2130, 2001[Abstract/Free Full Text].

37.   Wagner, JD. Rationale for hormone replacement therapy in atherosclerosis prevention. J Reprod Med 45: 245-258, 2000[ISI][Medline].

38.   Wakatsuki, A, Ikenoue N, and Sagara Y. Effects of estrogen on susceptibility to oxidation of low-density and high-density lipoprotein in postmenopausal women. Maturitas 28: 229-234, 1998[ISI][Medline].

39.   Walsh, SW, Vaughan JE, Wang Y, and Roberts LJ. Placental isoprostane is significantly increased in preeclampsia. FASEB J 14: 1289-1296, 2000[Abstract/Free Full Text].

40.   Yoon, BK, Oh WJ, Kessel B, Roh CR, Choi D, Lee JH, and Kim DK. 17beta -Estradiol inhibits proliferation of cultured vascular smooth muscle cells induced by lysophosphatidylcholine via a nongenomic antioxidant mechanism. Menopause 8: 58-64, 2001[ISI][Medline].

41.   Yura, T, Fukunaga M, Khan R, Nassar GN, Badr KF, and Montero A. Free-radical-generated F2-isoprostane stimulates cell proliferation and endothelin-1 expression on endothelial cells. Kidney Int 56: 471-478, 1999[ISI][Medline].

42.   Zhu, X, Bonet B, and Knopp RH. Estradiol-17beta inhibition of LDL oxidation and endothelial cell cytotoxicity is opposed by progestins to different degrees. Atherosclerosis 148: 31-41, 2000[ISI][Medline].

Am J Physiol Heart Circ Physiol 283(6):H2644-H2649
0363-6135/02 $5.00 Copyright © 2002 the American Physiological Society


This article has been cited by other articles:


Home page
 Am. J. Physiol. Heart Circ. Physiol.Home page
J. A. Ospina, S. P. Duckles, and D. N. Krause
17{beta}-Estradiol decreases vascular tone in cerebral arteries by shifting COX-dependent vasoconstriction to vasodilation
Am J Physiol Heart Circ Physiol, June 5, 2003; 285(1): H241 - H250.
[Abstract] [Full Text] [PDF]

This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow All Versions of this Article:
283/6/H2644    most recent
00369.2002v1
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 (5)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Hermenegildo, C.
Right arrow Articles by Cano, A.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Hermenegildo, C.
Right arrow Articles by Cano, A.

HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Visit Other APS Journals Online