Intrarenal blood flow distribution during endotoxemia in dogs

Intrarenal blood flow distribution during the stages of endotoxemia in the dog was studied using radioactive inert gas washout. Intrarenal blood flow distribution was determined: a) at control, b) 0.5 hours following injection of a lethal dose (3 mg/kg) of E coli endotoxin, and c) 2.5 hours following endotoxin injection in control dogs and dogs pretreated with 4 mg/kg of phenoxybenzamine. One-half hour following endotoxin injection, components I and II of the inert gas washout curve fused. Presumably this fusion occurred because component I flow decreased to a level indistinguishable from that of component II. Following 2.5 hours of endotoxemia, components I and II were both present. Pretreatment with phenoxybenzamine completely prevented the fusion of components I and II, although the mean arterial blood pressure was substantially lower than in dogs not pretreated with phenoxybenzamine. After 2.5 hours of endotoxemia, four of the five phenoxybenzamine pretreated dogs still had two clearly defined washout components. It is concluded that the renal cortical vascular response in endotoxemia is similar to that reported following hemorrhage and that the alpha-adrenergic nervous system plays a major role in decreasing renal cortical blood flow.