QUANTITATIVE EFFECTS OF GLUCOSE, SULFONYLUREAS, SALICYLATE, AND INDOLE-3-ACETIC ACID ON THE SECRETION OF INSULIN ACTIVITY INTO PANCREATIC VENOUS BLOOD*

Abstract

Phlorhizinized dogs were laparotomized under pentobarbital anesthesia and the pancreaticoduodenal vein draining the right pancreatic limb was cannulated. Outflow rate of insulin-activity (Vallance-Owen rat diaphragm method) was measured for 30 minutes after peripheral intravenous injection of glucose (30 g), tolbutamide, ehlorpropamide, salicylate, indole-3-acetic acid (all 50 mg/kg), or metahexamide (10 mg/kg). Although glucose and all 3 sulfonylureas promptly enhanced secretion of insulin-activity, the mean increase after glucose was 5 to 10 times greater than after sulfonylureas. Neither salicylate nor indole-3-acetic acid stimulated pancreatic release of insulin-activity. The data suggest that glucose is truly "insulogenic" (stimulates formation of new insulin), whereas sulfonylureas seem only able to release pre-formed stores of insulin.