SEX-DIFFERENCES IN THE EFFECTS OF 17-BETA-ESTRADIOL ON VASCULAR ADRENERGIC RESPONSES

The in vitro effects of 17 beta-estradiol on vascular responses to adr energic nerve stimulation were studied in perfused tail arteries from age-matched male and female rats. Nerve stimulation resulted in vasoco nstriction that was greater in male arteries. Addition of 17 beta-estr adiol (3 X 10(-5) M) reduced the vasoconstrictor responses in both mal e and female arteries, but the reduction was significantly greater in the females. Gonadectomy of the animals for 1 month prior to the exper iment did not alter the in vitro responses to 17 beta-estradiol in eit her males or females. 17 beta-Estradiol (10(-6)-3 X 10(-5) M) also rel axed perfused tail arteries precontracted with KCl (50 mM); however th e relaxation was not different between males and females, either intac t or gonadectomized. Stimulation-evoked release of noradrenaline from adrenergic nerves of perfused tail arteries was measured, but no diffe rences were found between males and females, nor was release modified by in vitro exposure to 17 beta-estradiol (10(-5) M). These results su ggest that 17 beta-estradiol acts directly on postjunctional mechanism s to relax tail arteries of either sex. The effect of the hormone on a rteries constricted by adrenergic nerve stimulation, however, is great er in females compared to males.