Role of prostaglandins in renin suppression during acute potassium loading

Acute K loading suppresses plasma renin activity (PRA) and may alter prostaglandin biosynthesis. To determine whether the effect of K on PRA was modulated through changes in the prostaglandin system, dietary NaCl-restricted rats were infused with prostaglandin I2. PRA was then determined before and 90 min after a KNO3 infusion. Control rats received only the prostaglandin infusion. PRA increased in rats receiving prostaglandins alone. K loading prevented the increase in PRA. To further exclude prostaglandins in PRA suppression during K loading, the effects of K on PRA were determined during prostaglandin inhibition with meclofenamate or indomethacin. K loading also suppressed PRA during prostaglandin inhibition. In neither study could the changes in PRA be attributed to changes in mean arterial pressure, glomerular filtration rate, plasma volume expansion, or urinary NaCl excretion rate. We conclude that the effects of K on PRA are independent of the prostaglandin system.