A comparison of the development of renal hypertension in male and female rats.

1. The objective of this study was to determine the influence of gender on the development of renal hypertension in Sprague-Dawley rats using the Goldblatt two-kidney, one-clip (2K1C) model. In addition, this study examined the effect of ovariectomy upon the development of hypertension in female rats.2. At 10 weeks of age, male, intact female and ovariectomized female rats underwent clipping of the right renal artery or sham operation. Tail-cuff plethysmography was used to monitor the systolic blood pressure of all animals for 7 weeks post-clipping or sham operation. Rats were sub-grouped according to whether or not they developed hypertension (systolic blood pressure >=150 mmHg).3. Within 2 to 3 weeks of clipping, hypertension was induced in only 53% (n=120) of the intact female 2K1C rats, but in 83% (n=18) of the male and 78% (n=18) of the ovariectomized female rats.4. Seven weeks after right renal artery clipping, plasma renin activity was determined in a subset of each group and was found to be 5-6 fold higher in male (17.29+/-4.04 ng angiotensin I.h-1.ml-1) and ovariectomized female (9.71+/-1.25 ng angiotensin I.h-1.ml-1) hypertensive rats compared with their respective normotensive or sham-operated counterparts (3.39+/-0.58 ng angiotensin I.h-1.ml-1 and 1.60+/-0.41 ng angiotensin I.h-1.ml-1 respectively) (P<0.05, analysis of variance). In contrast, the plasma renin activity measured in intact female hypertensive rats was not significantly different from that measured in the corresponding 2K1C normotensive or sham-operated groups.5. These results indicate that the success rate of inducing renal hypertension in Sprague-Dawley rats is higher in males than in intact females. Furthermore, these results suggest that the induction of 2K1C hypertension may be influenced by ovarian hormones.