Background: The benefits of chronic administration of estrogen to postmenopausal women are well documented; however, the acute effects of exogenous estradiol on myocardium after coronary artery occlusion and reperfusion in male and female animal models are unknown. We tested the influence of acute pretreatment with estradiol on the development of myocar dial necrosis in two protocols, studying intact anesthetized female and male rabbits.
Methods and Results: 17β-estradiol (1 mg) was given 15 minutes before coronary artery occlusion in the treated groups (n = 10 females, 10 males); control rabbits (n = 11 females, 10 males) received water. All rabbits underwent 30 minutes of coronary artery occlusion and 4 hours of reperfusion. Myocardial blood flow was similar between groups at 10 minutes after treatment and during coronary artery occlusion and reperfusion. Thus estradiol did not increase blood flow. Heart rate and systemic pressure were also similar between groups. Estradiol levels during coronary artery occlusion were 1-8 pg/mL in untreated female and male rabbits and 66 ± 28 (male) and 352 ± 273 (female) in treated rabbits. Although the size of the ischemic risk zones was similar in both groups in both protocols, estradiol-treated rab bits of both sexes developed significantly less necrosis. Infarct size as a percent of the risk region was 10 ± 1% in female estradiol-treated rabbits compared with 23 ± 5% in controls (P < .03) and 16 ± 4% in estradiol-treated male rabbits compared with 31 ± 5% in control males (P = .03). Although male rabbits had larger infarcts than female rabbits, sex was not a significant covariate for infarct size.
Conclusions: Estradiol exerts a protective effect on ischemic myocardium that is not associ ated with an increase in myocardial blood flow or alteration in hemodynamics. This study shows that acute administration of estrogen before coronary artery occlusion reduces infarct size in both male and female rabbits.
McHugh NA, Cook SM, Schairer JL, Bidgoli MM, Merrill GFIschemia- and reperfusion-induced ventricular arrhythmias in dogs: effects of estrogen. Am J Physiol268:H2569, 1995
2.
Farb A., Triemstra L., Kolodgie FD, Verma A., Virmani R.Cardioprotective effects of estradiol-17 beta in the isolated working female rat heart. J Am Coll Cardiol, Special Issue (Abstract): 231A, 1994
3.
Sudhir K., Chou TM, Muller WL, Hausmann D., Collins P., Yock PG, Chatterjee K.Mechanisms of estrogen-induced vasodilation: in vivo studies in canine coronary conductance and resistance arteries. J Am Coll Cardiol26:807, 1995
4.
Jiang C., Poole-Wilson PA, Sarrel PM, Mochizuki S., Collins P., MacLeod KTEffect of 17 beta-oestradiol on contraction, Ca2+ current and intracellular free Ca2+ in guinea pig isolated cardiac myocytes. Br J Pharmacol106:739, 1992
5.
Salas E.Lopez MG, Villarroya M.Sanchez-Garcia P., De Pascual R., Dixon WR, Garcia AGEndothelium-independent relaxation by 17-alpha-estradiol of pig coronary arteries . Eur J Pharmacol258:47, 1994
Keaney JF, Jr, Shwaery GT, Xu A.Nicolosi RJ, Loscalzo J., Foxall TL, Vita JA17β-estradiol preserves vasodilator function and limits low-density lipoprotein oxidation in hypercholesterolemic swine. Circulation89:2251, 1994
9.
Shan J.Resnick LM, Liu Q-Y., Wu X-C., Barbagallo M., Pang Pkt.Vascular effects of 17 beta-estradiol in male Sprague-Dawley rats. Am J Physiol266:H967, 1994
10.
Gilligan DM , Badar DM, Panza JA, Quyyumi AA, Cannon ROAcute vascular effects of estrogen in postmenopausal women. Circulation90:786, 1994
11.
Martin LG, Brenner GM, Jarolim KL, Banschbach MW, Coons DL, Wolfe AKEffects of sex steroids on myocardial anoxic resistance. Proc Soc Exp Biol Med202:288, 1993
