Enhancement of renal prostaglandin E2 and renin release by autoregulatory dilation of preglomerular vessels in dogs.

To examine the PGE2 and renin release during autoregulatory dilation of preglomerular vessels, experiments were performed in three groups of anesthetized dogs. By reducing the arterial perfusion pressure from 113 +/- 3 to 78 +/- 3 mm Hg, renin release rose to 20 +/- 50% and PGE2 release to 74 +/- 12% of the maximal values attained at two perfusion pressures below the range of autoregulation. During ureteral occlusion, PGE2 and renin release rose to maximal values already at control blood pressure and remained unaltered as the arterial perfusion pressure was reduced from 124 +/- 7 to 68 +/- 2 mm Hg. Renal blood flow fell in proportion to the perfusion pressure indicating abolished autoregulation. At a perfusion pressure below the range of autoregulation, saline infusion restored sodium excretion and reduced renin release but did not alter PGE2 release. We conclude that PGE2 release is raised by autoregulatory dilation of preglomerular arteries. Prostaglandins enhance renin release when afferent arterioles are dilated. Renin release mediated by a macula densa mechanism is not PGE2 dependent.