Hyperglycemic substances orginating in the pancreatoduodenal area

¹ Department of Physiology and Pharmacology, The Chicago Medical School, Chicago 12, Illinois

Glucagon, serotonin, deserpidine and the diethanolamine salt of p-tolymethyl carbinol camphoric acid ester (DTCE) were injected into the pancreatic, mesenteric or femoral artery, or into the portal or femoral vein of anesthetized normal dogs and dogs pretreated with dihydroergotamine (DHE) or with SA-97, a serotonin-blocking agent. Intraportal glucagon causes a fleeting, but a marked and significant elevation of plasma potassium and a marked and significant hyperglycemia. DHE blocks glucagon hyperkalemia, but not glucagon hyperglycemia. These effects are similar to the effects of glucagon injected into a peripheral vein and suggest that glucagon hyperkalemia may be mediated by a sympathomimetic amine. Serotonin causes a marked hyperglycemia which is not seen in animals pretreated with DHE or SA-97. Deserpidine causes an immediate and marked hyperglycemia when injected into the pancreatic artery, and a mild and delayed hyperglycemia if injected elsewhere. DTCE also causes hyperglycemia only when injected into the pancreatic artery. DHE blocks the effect of serotonin and of DTCE, but not that of deserpidine. It is suggested that more than one type of hyperglycemic substance may be produced in the area supplied by the pancreatic artery: one type which, like serotonin or the catecholamines, is blocked by DHE, and another type which, like glucagon, is unaffected by it.