Noradrenergic vasorelaxation of porcine coronary arteries is enhanced by direct, acute exposure to 17 beta-estradiol.
1. We tested whether responses of isolated coronary arteries to adrenergic agents are altered by overnight (18-22 hr) or acute exposure to physiological levels of 17 beta-estradiol. 2. Sensitivity to relaxation by norepinephrine (-log M ED50) was enhanced significantly in isolated arteries after acute exposure to 10(-9) M 17 beta-estradiol. Neither alpha-adrenergic contraction to norepinephrine, nor beta-adrenergic relaxation to isoproterenol was affected by acute exposure to 17 beta-estradiol. 3. Responses of coronary arteries to relaxation or contraction by norepinephrine, as well as relaxation by isoproterenol, were not altered by overnight incubation with 17 beta-estradiol or by removal of the endothelium. 4. We conclude that relaxation of coronary arteries by norepinephrine is enhanced by acute, direct exposure to physiological levels of 17 beta-estradiol. This enhancement does not result from effects of estradiol to suppress alpha-adrenergic contraction to norepinephrine or increase coronary beta-adrenergic receptor sensitivity.
Bell
D R
DR
Department of Physiology and Biophysics, Indiana University, School of Medicine, Fort Wayne 46805, USA.
Rensberger
H J
HJ
Koritnik
D R
DR
Koshy
A
A
D000818:Animals; D003331:Coronary Vessels / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D007545:Isoproterenol / Q000494:pharmacology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D009638:Norepinephrine / Q000494:pharmacology*; D013552:Swine
D004958:Estradiol; D007545:Isoproterenol; D009638:Norepinephrine