Dissociation of renin release and renal vasodilation by prostaglandin synthesis inhibitors

Abstract

Renal blood flow (RBF) and renin secretion rate (RSR) were measured during step reductions of renal perfusion pressure (RPP) within and below the autoregulatory range of RBF in the presence or absence of prostaglandin synthesis inhibitors. In 7 untreated dogs with reduction of RPP from 120 to 90 mmHg RBF did not change and RSR increased from 662 .+-. 90 to 2138 .+-. 121 ng/min (means .+-. SE). When RPP was further reduced to 60 mmHg, RBF decreased by 22% and RSR increased to 3259 .+-. 676 ng/min. After indomethacin administration renin release was 680 .+-. 171 before and 1044 .+-. 162 ng/min after RPP was reduced from 120 to 90 mmHg without affecting RBF. These values are not significantly different. Indomethacin did not affect the increase in the release of renin up to 3096 .+-. 629 ng/min when RPP was reduced to 60 mmHg. Comparable effects in the release of renin were exerted by meclofenamate. Reduction of RPP from control pressure to 83 mmHg was not accompanied by any significant change in RBF either before or after meclofenamate. RSR increased from 677 .+-. 317 to 2701 .+-. 851 ng/min before meclofenamate and from 249 .+-. 209 to 515 .+-. 288 ng/min after meclofenamate. Further reduction of RPP to 53 mmHg resulted in similar decreases in RBF before and after meclofenamate and increased RSR by 2658 .+-. 1120 before and 2206 .+-. 721 ng/min after meclofenamate. Inhibitors of prostaglandin synthesis apparently attenuate the release of renin within but not below the autoregulatory range of RBF.