THE EFFECTS OF THE MENSTRUAL-CYCLE, RACE, AND GENDER ON ADRENERGIC-RECEPTORS AND AGONISTS

Objective: To examine possible effects of race, sex, and the menstrual cycle on adrenergic receptors (beta(2) and alpha(2)) and agonists. Me thods: Sixty-three normotensive black men and women and white men and women were studied twice, approximately 6 weeks apart. Women were stud ied once during the follicular phase and once during the luteal phase of the menstrual cycle. beta(2)-Adrenergic receptors and adenylate cyc lase activity were examined on lymphocytes, and alpha(2)-adrenergic re ceptors were examined on platelets, Norepinephrine and epinephrine wer e determined in plasma, Results: Women showed greater lymphocyte beta( 2)-receptor sensitivity (isoproterenol-stimulated cyclic adenosine mon ophosphate; p = 0.009). Women also showed greater postreceptor adenyla te cycle activity independent of the beta-receptor (forskolin stimulat ion; p = 0.006). When these differences were controlled for, the gende r-related differences in beta(2)-receptor sensitivity were no longer e vident, Black women had a reduced beta(2)-receptor sensitivity in the luteal phase compared with the follicular phase, whereas white women s howed no significant change (p = 0.018). Black subjects had lower lymp hocyte beta(2)-receptor density (B-max) values than white subjects (p = 0.047). There were no significant effects on alpha(2)-adrenergic rec eptors. Conclusion: The findings suggest that although there is no gen eralized effect of the menstrual cycle on adrenergic receptors in whit e women, such an effect may occur in black women. The findings also su ggest that previously reported gender-related differences in beta(2)-r eceptor sensitivity may be due to gender-related differences in postre ceptor activity and not the beta(2)-receptor per se.