EFFECT OF PROSTAGLANDIN SYNTHETASE INHIBITORS ON RENIN AND ALDOSTERONE IN MAN ON A NORMAL OR LOW SODIUM DIET
ABSTRACT The effect of two inhibitors of prostaglandin synthetase activity (acetylsalicylic acid (ASA) and diclofenac sodium (DCFS)) on plasma renin activity (PRA) and plasma aldosterone (PA) was studied in normal subjects kept on a diet with constant sodium and potassium intake or on a low-salt diet for 7 days. In 9 subjects, 2 days of treatment with ASA (3 g/day) was followed by a significant decrease of PA in the supine position (after overnight rest); there was no significant decrease of PRA. However, both PA and PRA with the subjects in the upright position were significantly reduced after ASA. In 9 subjects treated with DCFS (200 mg for 2 days), both PA and PRA with the subjects in the supine and upright positions decreased significantly. Similar results were obtained from 4 subjects on a low-sodium diet (15–30 mEq./day) treated with DCFS (150 mg/day for 3 days). In contrast, no significant changes in PA or PRA with the subjects in the supine or upright position were observed in 4 subjects on a very low sodium diet (< 15 mEq./day) treated with DCFS (150 mg/day for 3 days). Covariance analysis (with PRA as independent variable and PA as dependent variable) of the data obtained in the upright position before and after treatment with ASA or DCFS showed that the decrease in PA remained significant after adjustment for the PRA effect. These results suggest a direct effect of prostaglandins on PA. The data obtained from subjects on a low sodium diet indicate that sodium deprivation may counteract the effects of DCFS on PRA and PA.