EFFECT OF CHRONIC GLUCAGON-ADMINISTRATION ON DIGESTIVE AND ABSORPTIVE FUNCTION OF RAT SMALL-INTESTINE INVIVO

Endogeneous hyperglucagonemia is observed in experimental diabetes mellitus and semistarvation, conditions associated with an increased intestinal absorptive function. To examine whether glucagon might exert a similar adaptive response on intestinal digestive-absorptive function like experimental diabetes mellitus the effect of chronic glucagon administration on intestinal transport of 3-O-methyl-D-glucose, H2O, Na, K, and D-glucose induced transmural potential difference (PD) was examined by an in vivo perfusion technique in rat small intestine. Chronic administration of glucagon (100 .mu.g twice daily) for 5 days increased absorption of 3-O-methyl-D-glucose, H2O, Na and K and increased D-glucose induced PD. A similar, but more pronounced augmentation of D-glucose induced PD was observed in the jejunum of streptozotocin-diabetic rats. Disaccharidase (maltase, sucrase, trehalase, lactase) and alkaline phosphatase activities were not affected in intestinal mucosa of glucagon-treated rats compared to controls. It cannot be decided from these results whether hyperglucagonemia is responsible for the adaptive intestinal changes observed in experimental diabetes mellitus.