LIVER PHOSPHORYLASE IN NORMAL AND ADRENALECTOMIZED DOGS TREATED WITH SEROTONIN1

Abstract

The hyperglycemic action of serotonin was investigated in 6 normal and 10 adrenalectomized dogs. In normal dogs, intravenous injections of serotonin were followed promptly by hyperglycemia, decreased liver glycogen and increased liver phosphorylase activity. In control adrenalectomized dogs treated with saline, a progressive decrease in blood glucose and liver glycogen was observed. Serotonin injections did not prevent these phenomena and caused only a delayed increase in phosphorylase activity. These results are consistent with the hypothesis that the increase of liver phosphorylase activity, glyco-genolysis, and blood glucose concentration observed in normal dogs, are not due to a direct stimulation of liver phosphorylase by serotonin, but are secondary to a release of epinephrine from the adrenal glands.