Gender differences in hemodynamic responses to endothelin-1

We investigated whether gender affects the presser and constrictor effects of endothelin-1 (ET-1) in anesthetized rats. Baseline values for arterial b lood pressure (mmHg) and hindquarter resistance (HQR, mmHg/ml/min/100 g), r espectively, were similar in male (96.0 +/- 3.1 and 13.9 +/- 0.6) and femal e (103.1 +/- 5.6 and ;12.8 +/- 23) rats. ET-1 (1 and 3 mug/kg) produced rap id and transient falls in arterial blood pressure and HQR, followed by long -lasting increases in blood pressure and HQR. The initial ET-1-induced hypo tension and vasodilation were similar in both groups. However, the presser and hindquarter vasoconstrictor effects were significantly higher (p < 0.05 ) in male than female rats. Thus, the increases in blood pressure and HQR t o ET-1 (3 <mu>g/kg) were attenuated in female (+15.3 +/- 3.4 mnHg and +3.7 +/- 1.6 mmHg/ml/min/100 g) compared to male (+24.9 +/- 2.3 mnHg and +8.0 +/ - 1.6 mmHg/ml/min/100 g) rats. These results indicate that there is a gende r difference in the vasoconstrictor, but not the vasodilator effects of ET- 1. We suggest that the lower ET-1-induced hypertension and hindlimb vasocon strictions observed in female rats may be responsible for the lower risk of developing coronary heart disease in premenopausal women.