Extrapancreatic glucagon and glucagonlike immunoreactivity in depancreatized dogs. A quantitative assessment of secretion rates and anatomical delineation of sources

Abstract

The anatomical sites and the rates of extrapancreatic secretion of glucagon and of glucagon-like immunoreactivity (GLI) were assessed in dogs 2 h after pancreatectomy by catheterization of the gastrosplenic and mesenteric veins. Glucagon release from the gastrosplenic area approximated one-fourth that of a normal pancreas and rose from 0.25 to 1.0 ng/kg per min during arginine stimulation. Intestinal glucagon secretion was small and did not respond to arginine, suggesting that the stomach is the only important extrapancreatic source of glucagon. Glucagon concentrations attained by gastrosplenic secretion were in close proportion to those obtained during the administration of exogenous glucagon, indicating similar clearance rates of extrapancreatic and pancreatic glucagon, approximating 10 ml/kg per min.GLI secretion (0.3 ng eq/kg per min) was limited to the intestinal area and was transiently stimulated by arginine and exogenous glucagon. Base-line GLI clearance approximated 1 ml/kg per min. No insulin secretion could be detected. Gastrointestinal glucose uptake rose from 0.56 to 2.2 mg/kg per min after glucagon administration suggesting that as much as 10% of total glucose production can be taken up by the gastrointestinal tract. In two dogs both the stomach and pancreas were removed. Intestinal glucagon release remained small and did not increase during arginine administration. By contrast, GLI release was stimulated by both arginine and exogenous glucagon.