The effects of male gender and female sex hormone deficiency on the vascular responses of the rat in vitro.
Male gender and menopause increase the risk for cardiovascular incidents by mechanisms that have not yet been fully clarified. Recent evidence suggests that the cardioprotective property of female sex hormones may be partly related to direct vasodilation. Accordingly, we examined the possible differences in arterial reactivity in vitro between normal female, ovariectomized female and normal male rats. Endothelium intact mesenteric artery rings were used to determine concentration response curves for noradrenaline, potassium chloride, acetylcholine and sodium nitroprusside. When compared to normal female rats, the maximal contractions to noradrenaline and potassium chloride were increased both in the ovariectomized female and in male rats. The relaxation induced by sodium nitroprusside was enhanced both in normal and ovariectomized females when compared to the male rats. There were no differences in relaxation responses to acetylcholine between normal or ovariectomized female or male rats. In conclusion, male gender and ovarian hormone deficiency increase arterial reactivity to constricting factors and reduce the vasodilatory effects of endothelium-independent relaxing agents.
Nevala
R
R
Department of Pharmacology and Toxicology, University of Helsinki, Finland.
Paakkari
I
I
Tarkkila
L
L
Vapaatalo
H
H
D000818:Animals; D005260:Female; D012739:Gonadal Steroid Hormones / Q000172:deficiency*; D066298:In Vitro Techniques; D008297:Male; D008638:Mesenteric Arteries / Q000187:drug effects; D009119:Muscle Contraction / Q000187:drug effects*; D009126:Muscle Relaxation / Q000187:drug effects*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D009599:Nitroprusside / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology; D010052:Ovariectomy; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D012737:Sex Factors
D012739:Gonadal Steroid Hormones; D009599:Nitroprusside; D011189:Potassium Chloride; D009638:Norepinephrine