The effect of conjugated estrogens on the renin-angiotensin system

In a survey of 3 California communities by the Stanford Heart Disease Prevention Program, we obtained data on blood pressure, medications, age, height and weight, blood for measurement of plasma renin activity (PRA), plasma renin concentration (PRC), plasma renin reactivity (RR), and plasma renin substate concentration (PRS), and urine for measurement of urinary sodium and creatinine. No effect of conjugated estrogens (Premarin) on blood pressure could be discerned when the blood pressure, corrected for age and relative weight, of 575 women on no medication was compared to that of 82 women taking only Premarin. Premarin increased PRA, PRS, and RR, but had no effect on PRC. We also found in both Premarin-treated woman and controls 1) that RR was positively correlated with PRS, and 2) that PRA is dependent on PRC and PRS. These data indicate that the reninrenin substrate reaction of plasma, even at normal substrate concentration, is strongly deprendent on PRS.