Introduction of L-leucine (0.2 gm.) in saline into the pancreatic artery in anesthetized dogs pretreated with chlorpropamide caused a marked peripheral venous hypoglycemia. Intraportal administration of leucine to sensitized dogs failed to produce the effect, as did injection of leucine or tolbutamide separately into the pancreas in the absence of pretreatment. Fall in blood glucose caused by infusion of leucine and tolbutamide concurrently into the pancreatic artery was not significantly different from that due to infusion into the portal vein.

The hypoglycemia is most likely due to insulin secretion from pancreatic islets sensitized by action of chlorpropamide to the stimulating effect of leucine. Intraportal infusion of tolbutamide and leucine produced a greater fall in venous blood glucose than a doubled amount of tolbutamide alone. This might support the idea of a second action of leucine that might enhance the effect of endogenous insulin on the liver.

This content is only available via PDF.