Effects of Menstrual Cycle and Race on Peripheral Vascular α-Adrenergic Responsiveness

Publisher Website
Google Scholar
Abstract
Abstract —Gender differences in the incidence of many cardiovascular diseases may be due to the effects of sex hormones. Both α 1 - and α 2 -adrenergic receptors produce vasoconstriction in peripheral blood vessels and have demonstrated gender effects in previous studies. In addition, race has been shown to influence the effects of some α-adrenergic stimuli. We therefore sought to determine the effects of the menstrual cycle and race on peripheral blood flow responses to the intra-arterial infusion of phenylephrine (α 1 -agonist) and clonidine (α 2 -agonist). Ten white and 8 black women were studied during the early luteal phase and the follicular phase; these phases were verified in each woman through measurements of plasma estradiol and progesterone. Plasma norepinephrine was measured with HPLC. During phenylephrine infusion, there was significantly greater vasoconstriction in the luteal phase versus the follicular phase ( P 0.8) between white and black women. During clonidine infusion, white women showed significantly more vasoconstriction in the follicular phase than during the luteal phase ( P 0.9). Blood pressures were significantly higher in the black women (diastolic P P 1 -adrenergic responses may be due to elevated levels of estradiol, progesterone, or both. The lack of luteal-phase reduction in α 2 -adrenergic vasoconstriction in black women may contribute to their increased pressor responses to adrenergic stimuli.