6-Keto-prostaglandin E1 is more potent than prostaglandin I2 as a renal vasodilator and renin secretagogue.

Several studies indicate that prostaglandin (PG) I2 is involved in the control of renin release. This investigation was performed to determine if the active possible metabolite of PGI2, 6-keto-PGE1, is also 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 seven anesthetized dogs. Intrarenal infusions of both PGI2 and 6-keto-PGE1 significantly augmented RSR in a dose-related fashion. However, 6-keto-PGE1 was approximately 5 times more potent than PGI2, producing significantly greater increases in RSR at doses from 3 X 10(-9) to 3 X 10(-8 g/kg/min (P < .03). At low infusion rates (less than 3 X 10(-8) g/kg/min), 6-keto-PGE1 enhanced RBF to a greater extent than PGI2. However, with infusion rates of 3 X 10(-8) g/kg/min, these eicosanoides enhanced RBF to an equal extent. Thus, in comparison to PGI2, 6-keto-PGF1 induced a greater increase in RSR for equivalent increases in RBF. 6-keto-PGF 1 alpha had no effect on either RSR or RBF at any of the doses infused. We conclude that, in the canine kidney, 6-keto-PGE1 is more potent than PGI2 in stimulating the juxtaglomerular cells to secrete renin.