Mechanism of effect of diphenylhydantoin on renal renin release

This study was undertaken to delineate the mechanism of the effect of diphenylhydantoin (DPH) on renal renin release. DPH at a dose of 0.18 mg X kg-1 X min-1 was infused for 30 min into the renal artery of anesthetized dogs with acute unilateral renal denervation. In the innervated kidney, DPH infusion increased renin secretion rate (RSR) from 189 +/- 54 to 939 +/- 279 ng ANG I X h-1 X min-1. In the contralateral denervated kidneys, RSR did not change. An identical study was done in a second group of dogs in which unilateral renal denervation was done 24 h prior to DPH infusion. In this group, DPH infusion increased RSR from 63 +/- 57 to 643 +/- 180 ng ANG I X h-1 X min-1 in the innervated kidneys. In the contralateral denervated kidneys, RSR did not change. In a separate group of indomethacin-treated nondenervated dogs, intrarenal infusion of DPH increased RSR from 131 +/- 32 to 452 +/- 88 ng ANG I X h-1 X min-1. The percent increase in RSR in the indomethacin-treated dogs was not significantly different from the non-indomethacin-treated dogs. These data suggest that the stimulatory effect of DPH on renin release is mediated by or requires the presence of renal nerves. The step(s) after the renal nerves is (are) not mediated by prostaglandins.