6-KETO-PROSTAGLANDIN-E1 IS MORE POTENT THAN PROSTAGLANDIN-I2 AS A RENAL VASODILATOR AND RENIN SECRETAGOGUE

Abstract

Prostaglandin(PG)I2 apparently is involved in the control of renin release. The active possible metabolite of PGI2, 6-keto-PGE1, was investigated as a renin secretagogue. The relative potencies of PGI2, 6-keto-PGE1 and 6-keto-PGF1.alpha. on renin secretion rate (RSR) and renal blood flow (RBF) were assessed in nonfiltering, .beta. adrenoreceptor blocked kidneys of 7 anesthetized dogs. Intrarenal infusions of PGI2 and 6-keto-PGE1 significantly augmented RSR in a dose-related fashion. 6-Keto-PGE1 was .apprx. 5 times more potent than PGI2, producing significantly greater increases in RSR at doses of 3 .times. 10-9 to 3 .times. 10-8 g/kg per min (P < 0.03). At low infusion rates (< 3 .times. 10-8 g/kg per min), 6-keto-PGE1 enhanced RBF to a greater extent than PGI2. With infusion rates of 3 .times. 10-8 g/kg per min, these eicosanoides enhanced RBF to an equal extent. Compared to PGI2, 6-keto-PGE1 induced a greater increase in RSR for equivalent increases in RBF. 6-keto-PGF1.alpha. had no effect on RSR or RBF at any dose infused. In the canine kidney, 6-keto-PGE1 is evidently more potent than PGI2 in stimulating the juxtaglomerular cells to secrete renin.