This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Reis, S. E. Articles by Murali, S. Search for Related Content PubMed PubMed Citation Articles by Reis, S. E. Articles by Murali, S.

(Circulation. 1998;97:23-25.)
© 1998 American Heart Association, Inc.

Brief Rapid Communications

Conjugated Estrogens Acutely Abolish Abnormal Cold-Induced Coronary Vasoconstriction in Male Cardiac Allografts

Steven E. Reis, MD; Vishwajeth Bhoopalam, MD; Kathleen A. Zell, BSN; Peter J. Counihan, MD; A. J. Conrad Smith, MD; Si Pham, MD; ; Srinivas Murali, MD

From the Division of Cardiology, Department of Medicine and the Division of Cardiothoracic Surgery, Department of Surgery (S.P.), University of Pittsburgh (Pa) School of Medicine.

Correspondence to Steven E. Reis, MD, University of Pittsburgh Medical Center, 200 Lothrop St, Pittsburgh, PA 15213.

	Abstract

Top Abstract Introduction Methods Results Discussion References

 
Background—Transplant-associated coronary arteriopathy is manifested in its early stages by paradoxical coronary artery constriction in response to endothelium-dependent vasodilator stimuli such as the cold pressor test (CPT) and is a major cause of death or retransplantation. Estrogen has vasoactive properties that abolish coronary artery endothelial dysfunction in native hearts. We hypothesized that estrogen attenuates inappropriate coronary artery constriction in cardiac allografts.

Methods and Results—Coronary artery diameter and systemic hemodynamic responses to a 90-second CPT were measured before and 15 minutes after double-blind, randomized administration of intravenous conjugated estrogens (1.25 mg) or placebo in men with male cardiac allografts. Before estrogen, 9 men exhibited an abnormal 15.1±3.0% CPT-induced decrease in coronary artery diameter. However, repeat CPT did not induce significant coronary artery constriction when performed 15 minutes after estrogen. CPT responses before and after estrogen were significantly different (P=.02). Placebo did not influence coronary artery responses to CPT in 6 men. Systemic hemodynamic responses to CPT were not influenced by estrogen or placebo. Estrogen was the only significant determinant of changes in coronary artery responses to CPT.

Conclusions—Conjugated estrogens acutely abolish abnormal CPT-induced coronary artery constriction in male cardiac allografts. This favorable vasomotor effect suggests that estrogen may prevent inappropriate coronary artery constriction in men with cardiac transplants.

Key Words: transplantation • hormones • endothelium • coronary disease • atherosclerosis

	Introduction

Top Abstract Introduction Methods Results Discussion References

 
Allograft coronary arteriopathy is a major cause of death or retransplantation in cardiac transplant recipients.¹ Early transplant-associated arteriopathy is manifested by coronary artery endothelial dysfunction, which precedes the development of angiographically documented disease.² This physiological abnormality may be detected in cardiac allografts by measurement of coronary artery responses to endothelium-dependent vasodilator stimuli, such as the cold pressor test (CPT), that induce dilatation in coronary arteries with intact endothelium and paradoxical constriction in those with endothelial dysfunction.³

Estrogen has vasomotor properties that prevent in vitro arterial constriction and inappropriate coronary artery constriction in native human hearts.^{4 5 6 7 8 9 10 11 12} Estrogen-induced attenuation of abnormal coronary vasoreactivity may provide a clinical cardioprotective effect because inappropriate coronary artery constriction has been implicated in the pathogenesis of acute cardiac syndromes. We hypothesized that estrogen attenuates inappropriate coronary artery constriction in cardiac allografts.

	Methods

Top Abstract Introduction Methods Results Discussion References

 
Cardiac transplant recipients undergoing routine posttransplant coronary angiography were eligible to participate. All subjects gave written informed consent approved by the University of Pittsburgh Biomedical Institutional Review Board.

Assessment of Coronary Hemodynamics
Vasodilator drugs were discontinued for at least 24 hours. Routine coronary angiography was performed by standard techniques, and a "normal" coronary artery was selected for assessment. Heart rate and systemic blood pressure were recorded, and coronary artery diameter was measured at a fixed anatomic location relative to a branch point by quantitative angiography (AWOS, Siemens Medical Systems) performed by an investigator (V.B.) blinded to treatment group. The reliability (ratio of the inherent variance of the measurement between patients to the variance from all sources) is 0.94, as assessed by analysis of the variance components.

Effects of Estrogen on Coronary Artery Responses to the CPT
After baseline hemodynamics and coronary artery diameter were measured, a CPT was performed with the subject's hand immersed in ice water for 90 seconds. At the conclusion of the CPT, systemic hemodynamics and coronary artery diameter were reassessed. Intravenous conjugated estrogens (Premarin 1.25 mg, Wyeth-Ayerst) or placebo was administered in a double-blind, randomized fashion. Fifteen minutes later, hemodynamics and coronary artery diameter were reassessed at baseline and after a repeat CPT. Intrinsic vasodilatorcapacity was evaluated by measuring coronary artery diameter after intracoronary nitroglycerin (200 µg).

Statistical Analysis
The data are expressed as mean±SEM. Values of P.05 are considered significant. Only subjects who exhibited no change or a paradoxical decrease in coronary artery diameter in response to CPT were selected for analysis, because we previously demonstrated that estrogen does not improve vasoreactivity in coronary arteries that dilate normally in response to an endothelium-dependent stimulus.⁸ Baseline characteristics were compared between groups by ² analysis and Fisher's exact test and the independent Student's t test. Within each group, the influence of CPT on hemodynamics and coronary artery diameter was assessed by the paired Student's t test.

To assess the influence of pharmacological intervention (estrogen or placebo) on coronary artery responses to CPT, we first calculated the difference between coronary artery diameter after CPT and at baseline (D=diameter_CPT-diameter_baseline). The effects of intervention on coronary artery diameter were then quantified by calculation of the difference between D before and after intervention [(D)=D_{after intervention}-D_{before intervention}] followed by linear regression analysis.

	Results

Top Abstract Introduction Methods Results Discussion References

 
Twenty-seven patients were enrolled and randomized to estrogen or placebo. Fifteen exhibited abnormal CPT-induced coronary artery constriction and were included in the analysis. All subjects were men, because no postmenopausal female cardiac transplant recipients underwent coronary angiography during the study. All allografts were from male donors. Nine of the analyzed subjects received estrogen, and 6 received placebo. The Table demonstrates no significant differences in baseline characteristics between groups.

View this table: [in this window] [in a new window]   Table 1. Demographic Characteristics

Effects of Estrogen on CPT-Induced Coronary Artery Constriction
Conjugated estrogens acutely abolished abnormal CPT-induced coronary artery constriction in male cardiac allografts. Men assigned to estrogen exhibited a 15.1±3.0% decrease in coronary artery diameter (from 3.3±0.3 to 2.8±0.3 mm, P<.01) in response to the initial CPT but no significant diameter change in response to repeat CPT performed 15 minutes after estrogen (3.1±0.3 to 3.2±0.2 mm, P=NS). Coronary artery constriction elicited by the first CPT was significantly different from the coronary artery response elicited by the postestrogen CPT (P=.02).

Placebo did not influence coronary artery responses to CPT. Before placebo, the studied men exhibited an insignificant 9.0±3.8% decrease in coronary artery diameter (from 2.7±0.4 to 2.5±0.4 mm, P=.07) in response to CPT. Fifteen minutes after placebo, their coronary artery diameters also did not change significantly in response to repeat CPT (2.5±0.4 to 2.5±0.4 mm, P=NS). Coronary artery responses to the CPT did not differ before and after placebo.

Multivariate analysis demonstrated that estrogen was the only significant determinant of changes in coronary artery diameter responses to CPT. Other variables, including age, baseline coronary artery diameter, systemic hemodynamic response to CPT, intrinsic coronary artery vasodilator capacity, and degree of rejection did not influence coronary artery responses to CPT.

Effects of Estrogen on CPT-Induced Changes in Systemic Hemodynamics
CPT-induced endothelium-dependent vasodilatation requires a cold-induced increase in catecholamines, which may be assessed indirectly by measurement of changes in blood pressure. In subjects assigned to estrogen, baseline CPT induced a mean 11.3±2.2% increase in mean blood pressure (from 113.4±5.9 to 126.2±6.9 mm Hg, P<.01), which was not significantly different from the 12.5±3.1% increase (from 118.0±5.4 to 132.9±7.2 mm Hg, P<.01) induced by repeat CPT performed 15 minutes after estrogen. In placebo subjects, baseline CPT induced a 17.1±3.0% increase in mean blood pressure (from 111.5±5.0 to 130.0±4.3 mm Hg, P<.01), which did not differ from the 23.4±7.3% increase (from 107.7±5.2 to 131.5±4.9 mm Hg, P=.01) induced by repeat CPT performed after placebo. These blood pressure responses to CPT are similar to those observed in patients who did not receive transplants.^{10 11}

Although our transplant patients exhibited a normal blood pressure response to CPT, cardiac allografts are denervated and may not manifest an appropriate chronotropic response to adrenergic stimulation. In the men assigned to estrogen, baseline CPT induced a 2.7±0.7% increase in heart rate (from 78.8±3.0 to 80.9±3.1 bpm, P<.01), and postestrogen CPT induced a similar 3.2±1.3% increase in heart rate (from 77.1±3.0 to 79.4±2.8 bpm, P=.04). Placebo patients increased their heart rate by 5.8±0.8% (from 76.0±5.7 to 80.3±5.9 bpm, P<.01) in response to preplacebo CPT and did not exhibit a significant change in heart rate (from 79.3±6.0 to 80.0±6.3 bpm, P=NS) in response to postplacebo CPT. Overall, the study population had smaller CPT-induced increases in heart rate than a nontransplant population.^{10 11} However, heart rate is not a determinant of baseline coronary artery diameter or of coronary artery responses to CPT.

	Discussion

Top Abstract Introduction Methods Results Discussion References

 
This study demonstrates that estrogen attenuates abnormal coronary artery vasoreactivity in male cardiac allografts. Intravenous conjugated estrogens acutely abolished the abnormal 15.1% decrease in coronary artery diameter induced by the CPT in men with cardiac transplants. This finding was independent of cold-induced changes in systemic hemodynamics and degree of rejection. In contrast, placebo did not influence coronary artery responses to exogenous cold exposure.

Previous studies of transplant recipients have described abnormal coronary artery constriction in response to exogenous cold exposure that has been attributed to immune system–mediated graft endothelial dysfunction.^{13 14} The present study confirms this finding and demonstrates that it may be acutely abolished by intravenous conjugated estrogens. Although we used conjugated estrogens because they contain a potent vasoactive compound (17-dihydroequilenin), it is possible that multiple components of this preparation influenced coronary artery responses to CPT. The favorable vasomotor effects of estrogen in cardiac allografts may be related to estrogen-induced inhibition of endothelin-1 and calcium-mediated vasoconstriction, an increase in arterial endothelial nitric oxide, and/or alteration of arterial myocyte ATP-sensitive potassium channels.^{4 5 6 7}

Another possible explanation for our findings is that estrogen may lessen the degree of cold-induced sympathetic stimulation of the coronary arteries.¹⁵ Although we did not measure catecholamine responses to each of the two CPTs, we demonstrated that estrogen does not affect CPT-induced changes in blood pressure, which is a physiological surrogate marker of catecholamines. Therefore, it is unlikely that inhibition of cold-induced sympathetic stimulation explains the observed favorable effect of estrogen.

Our study is limited by our use of the CPT to assess coronary vasoreactivity. Cardiac allografts are denervated, as manifested in this study by their attenuated chronotropic response to CPT. However, - and ß-adrenergic receptors on graft coronary arteries regulate vasomotor tone and respond to circulating catecholamines in an endothelium-dependent manner independent of cardiac denervation. In addition, our findings are consistent with those reported in coronary arteries of native hearts.^{10 11}

Estrogen modulates the immune system and inhibits in vivo allograft rejection. Lou and colleagues¹⁶ demonstrated that chronic estradiol treatment abolishes MHC class II antigen expression, decreases cellular infiltration of the arterial wall, and inhibits myointimal proliferation in coronary arteries of New Zealand White rabbits that underwent cardiac transplantation. Local administration of estrogen has also been shown to inhibit insulin-like growth factor I–induced atherosclerosis in rat orthotopic abdominal aortic allotransplants.¹⁷ These findings suggest that chronic estrogen therapy may be a novel approach to inhibiting the progression of coronary arteriopathy in human cardiac allografts. Our results demonstrate that estrogen also acutely prevents inappropriate coronary artery constriction. Although it is not known whether these results may be extrapolated to chronic estrogen therapy, estrogen-induced improvement in coronary artery vasomotor tone may also provide a cardiovascular benefit in cardiac transplant patients. Other studies have demonstrated that nonfeminizing phytoestrogens have favorable vascular properties,¹⁸ suggesting their potential utility in men. Therefore, estrogen should be evaluated as a novel antiatherosclerotic therapy in male and female transplant recipients.

Received September 11, 1997; revision received October 24, 1997; accepted October 27, 1997.

	References

Top Abstract Introduction Methods Results Discussion References

 
1. Gao SZ, Alderman EL, Schroeder JS, Silverman JF, Hunt SA. Accelerated coronary vascular disease in the heart transplant patient: coronary arteriographic findings. J Am Coll Cardiol. 1988;12:334–340.[Abstract]

2. Fish RD, Nabel EG, Selwyn AP, Ludmer PL, Mudge GH, Kirshenbaum JM, Schoen FJ, Alexander RW, Ganz P. Responses of coronary arteries of cardiac transplant patients to acetylcholine. J Clin Invest. 1988;81:21–31.

3. Nabel EG, Ganz P, Gordon JB, Alexander RW, Selwyn AP. Dilation of normal and constriction of atherosclerotic coronary arteries caused by the cold pressor test. Circulation. 1988;77:43–52.[Abstract/Free Full Text]

4. Sudhir K, Chou TM, Mullen WL, Hausmann D, Collins P, Yock PG, Chatterjee K. Mechanisms of estrogen-induced vasodilatation: in vivo studies in canine coronary conductance and resistance arteries. J Am Coll Cardiol. 1995;26:807–814.[Abstract]

5. Jiang CW, Sarrel PM, Poole-Wilson PA, Collins P. Acute effect of 17ß-estradiol on rabbit coronary artery contractile responses to endothelin-1. Am J Physiol. 1992;263:H271–H275.[Abstract/Free Full Text]

6. Jiang C, Sarrel PM, Lindsay DC, Poole-Wilson PA, Collins P. Endothelium-independent relaxation of rabbit coronary artery by 17ß-oestradiol in vitro. Br J Pharmacol. 1991;104:1033–1037.[Medline] [Order article via Infotrieve]

7. Van Buren GA, Yang DS, Clark KE. Estrogen-induced uterine vasodilatation is antagonized by L-nitroarginine methyl ester, an inhibitor of nitric oxide synthesis. Am J Obstet Gynecol. 1992;167:828–833.[Medline] [Order article via Infotrieve]

8. Reis SE, Gloth ST, Blumenthal RS, Resar JR, Zacur HA, Gerstenblith G, Brinker JA. Ethinyl estradiol acutely attenuates abnormal coronary vasomotor responses to acetylcholine in postmenopausal women. Circulation. 1994;89:52–60.[Abstract/Free Full Text]

9. Blumenthal RS, Heldman AW, Brinker JA, Resar JR, Coombs VJ, Gloth ST, Gerstenblith G, Reis SE. Conjugated estrogens acutely improve the coronary blood flow response to acetylcholine in men. Am J Cardiol. In press.

10. Reis SE, Blumenthal RS, Gloth ST, Resar JR, Gerstenblith G, Brinker JA. Estrogen acutely abolishes cold-induced coronary vasoconstriction in postmenopausal women. Circulation. 1994;90(suppl I):I-86. Abstract.

11. Reis SE, Wu CC, Counihan PJ, Smith AJC, Cohen HA, Zell KA, Blumenthal RS, Feldman MD. Estrogen has an acute beneficial effect on coronary vasoreactivity in men. Circulation. 1995;92(suppl I):I-249. Abstract.

12. Gilligan DM, Quyyumi AA, Cannon RO. Effects of physiological levels of estrogen on coronary vasomotor function in postmenopausal women. Circulation. 1994;89:2545–2551.[Abstract/Free Full Text]

13. Kofoed KF, Czernin J, Johnson J, Kobashigawa J, Phelps ME, Laks H, Schelbert HR. Effects of cardiac allograft vasculopathy on myocardial blood flow, vasodilatory capacity, and coronary vasomotion. Circulation. 1997;95:600–606.[Abstract/Free Full Text]

14. Benvenuti C, Apetecar E, Mazzucotelli JP, Jouannot P, Loisance D, Nitenberg A. Coronary artery response to cold pressor test is impaired early after operation in heart transplant recipients. J Am Coll Cardiol. 1995;26:446–451.[Abstract]

15. Del Rio G, Velardo A, Zizzo G, Avogaro A, Cipolli C, Della Casa L, Marrama P, MacDonald IA. Effect of estradiol on the sympathoadrenal response to mental stress in normal men. J Clin Endocrinol Metab. 1994;79:836–840.[Abstract]

16. Lou H, Kodama T, Zhao YJ, Maurice P, Wang YN, Katz N, Foegh ML. Inhibition of transplant coronary arteriosclerosis in rabbits by chronic estradiol treatment is associated with abolition of MHC class II antigen expression. Circulation. 1996;94:3355–3361.[Abstract/Free Full Text]

17. Motomura N, Lou H, Hong M, Tsutsumi Y, Mayumi T, Foegh ML. Local administration of estrogen inhibits transplant arteriosclerosis in rat aorta accelerated by topical exposure to IGF-I. Transplant Proc. 1997;29:1118–1120.[Medline] [Order article via Infotrieve]

18. Honore EK, Williams JK, Anthony MS, Clarkson TB. Soy isoflavones enhance coronary vascular reactivity in atherosclerotic female macaques. Fertil Steril. 1997;67:148–154.[Medline] [Order article via Infotrieve]

This article has been cited by other articles:

				B. Xue, Y. Zhao, A. K. Johnson, and M. Hay Central estrogen inhibition of angiotensin II-induced hypertension in male mice and the role of reactive oxygen species Am J Physiol Heart Circ Physiol, September 1, 2008; 295(3): H1025 - H1032. [Abstract] [Full Text] [PDF]

				K. Tsuda, I. Nishio, M. Weis, J. P. Cooke, K. Y. Lin, S. N. Panchal, S.Z. Gao, H. A. Valantine, T. N. Kledal, and E. S. Mocarski Sex Hormones and Asymmetric Dimethylarginine in Transplant Arteriosclerosis * Response Circulation, July 20, 2004; 110(3): e21 - e22. [Full Text] [PDF]

				M. E. Mendelsohn and G. M.C. Rosano Hormonal Regulation of Normal Vascular Tone in Males Circ. Res., December 12, 2003; 93(12): 1142 - 1145. [Full Text] [PDF]

				S. Adamopoulos, D. Leftheriotis, E. Sbarouni, G. Karavolias, and D. T. Kremastinos Acute haemodynamic effects of oestrogen administration in male patients with chronic heart failure Eur J Heart Fail, December 1, 2002; 4(6): 719 - 726. [Abstract] [Full Text] [PDF]

				G. Polvani, M. R. Marino, M. Roberto, L. Dainese, A. Parolari, G. Pompilio, S. D. Matteo, A. Fumero, A. Cannata, F. Barili, et al. Acute effects of 17{beta}-estradiol on left internal mammary graft after coronary artery bypass grafting Ann. Thorac. Surg., September 1, 2002; 74(3): 695 - 699. [Abstract] [Full Text] [PDF]

				R. K. Dubey, S. Oparil, B. Imthurn, and E. K. Jackson Sex hormones and hypertension Cardiovasc Res, February 15, 2002; 53(3): 688 - 708. [Abstract] [Full Text] [PDF]

				P. A. Komesaroff, M. Fullerton, M. D. Esler, A. Dart, G. Jennings, and K. Sudhir Low-Dose Estrogen Supplementation Improves Vascular Function in Hypogonadal Men Hypertension, November 1, 2001; 38(5): 1011 - 1016. [Abstract] [Full Text] [PDF]

				S. C. Manolagas and S. Kousteni Perspective: Nonreproductive Sites of Action of Reproductive Hormones Endocrinology, June 1, 2001; 142(6): 2200 - 2204. [Full Text] [PDF]

				R. K. Dubey and E. K. Jackson Estrogen-induced cardiorenal protection: potential cellular, biochemical, and molecular mechanisms Am J Physiol Renal Physiol, March 1, 2001; 280(3): F365 - F388. [Abstract] [Full Text] [PDF]

				H. A. Walker, T. S. Dean, T. A. B. Sanders, G. Jackson, J. M. Ritter, and P. J. Chowienczyk The Phytoestrogen Genistein Produces Acute Nitric Oxide-Dependent Dilation of Human Forearm Vasculature With Similar Potency to 17{beta}-Estradiol Circulation, January 16, 2001; 103(2): 258 - 262. [Abstract] [Full Text] [PDF]

				K. Sudhir and P. A. Komesaroff Cardiovascular Actions of Estrogens in Men J. Clin. Endocrinol. Metab., October 1, 1999; 84(10): 3411 - 3415. [Full Text] [PDF]

				M. E. Mendelsohn and R. H. Karas The Protective Effects of Estrogen on the Cardiovascular System N. Engl. J. Med., June 10, 1999; 340(23): 1801 - 1811. [Full Text] [PDF]

This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Reis, S. E. Articles by Murali, S. Search for Related Content PubMed PubMed Citation Articles by Reis, S. E. Articles by Murali, S.