Loss of the Renal Vasoconstrictor Activity of Angiotensin II during Renal Ischemia*

Abstract

In dogs anesthetized with morphine-chloralose the induction of renal ischemia resulted in the loss of the renal vasoconstrictor activity of angiotensin II during the period of ischemia. Before renal ischemia, intravenous administration of angiotensin II (0.1 [mu]g per kg) elicited a 49% reduction in renal blood flow (RBF). Constriction of the renal artery reduced the RBF 59% (from 174 ml per minute to 72 ml per minute). After induction of renal ischemia, intravenous administration of angiotensin II (0.1 [mu]g per kg) produced a 67% increase in RBF (mean of 42 observations in 24 experiments). An equipressor dose of levarterenol during renal ischemia produced a further reduction in RBF (35%). Renal denerva-tion resulted in the loss of the renal vascular action of angiotensin II Ln the nonischemic state. A reduction or loss of the renal vascular response to angiotensin II in the nonischemic kidney developed frequently, particularly after prolonged periods of renal ischemia.