SEX-DIFFERENCES IN VASCULAR REACTIVITY TO ADRENERGIC AGENTS IN THE RAT

1. The study was designed to determine if there are sex-dependent differences in vascular reactivity to adrenergic agents. 2. Vascular reactivity of both aortic and tail artery smooth muscle from male and female rats to various vasoactive agents was assessed. 3. The vascular response of aortic smooth muscle to both phenylephrine and isoproterenol were significantly greater in male rats as compared to females. 4. There were apparent sex differences in responsiveness to the KCl-induced, non-receptor mediated contraction of aortic smooth muscle in that the sensitivity to KCl was enhanced in male rats. 5. No sex differences were observed in tail artery preparations. 6. Phentolamine reduced the maximal tension induced by KCl in the tail artery but not aortic artery preparations. This effect was not sex dependent. 7. No differences in the vascular smooth muscle responsiveness to acetylcholine or sodium nitrate was observed between groups or within different vascular beds. 8. The increased sensitivity of males to adrenergic challenge could explain in part some of the existing sex differences in cardiovascular disease and hypertension.