Plasma Glucose,Insulin,Pancreatic,and Enteroglucagon Levels in Normal and Depancreatized Dogs 1

Abstract

Summary and Conclusion

Pancreatic glucagon (IRG), total glucagon-like immunoreactive material (GLI), enteroglucagon (calculated from GLI and IRG values), glucose, and insulin (IRI) were measured in the systemic plasma of normal and depancreatized dog. IRG, GLI, and enteroglucagon began to increase 1 or 2 days after pancreatectomy, respectively, reaching values that were several times greater than those observed before the operation. Glucose, already elevated 1 hr after pancreatectomy, continued to increase thereafter; IRI showed a progressive decline. In other experiments, 50 ml of a 5% glucose solution were injected into 30-cm loops prepared from the upper portion of the jejunum or the lower portion of the ileum and blood samples were obtained from the regional mesenteric veins. Plasma enteroglucagon rose more and plasma glucose less when glucose was introduced into the ileum than when it was introduced into the jejunum. The enteroglucagon responses to glucose were much greater in depancreatized than in normal dogs. In the depancreatized animals, a single injection of regular insulin (0.4 U/kg; im), sufficient to produce a significant elevation of the plasma IRI level but only a moderate decrease in plasma glucose, caused a prompt and significant decrease in the systemic plasma IRG, GLI, and enteroglucagon levels. We conclude that in the dogs, the ileum is a major source of enteroglucagon and that removal of the pancreas increases the secretion of this hormone, a phenomenon reversed in part by insulin therapy.