Dissociation of glucose stimulation of somatostatin and insulin release from glucose inhibition of glucagon release in the isolated perfused rat pancreas.
This study investigated the modulating role of glucose on 5 mM arginine stimulation of insulin, somatostatin, and glucagon release from the isolated perfused rat pancreas. As the concentration of glucose was increased linearly from 50 to 300 mg/dl, arginine-stimulated glucagon release was inhibited, with half-maximal inhibition occurring at 84 mg/dl glucose. As glucose increased above 80 mg/dl, somatostatin and insulin release was initiated and they continued to increase in a nearly parallel fashion during the glucose gradient (300 mg/dl). When 5 mM arginine was presented "en block" against varying backgrounds of glucose (30, 60, 75, 90, 120, 150, and 300 mg/dl), glucagon release was diminished in the presence of glucose concentrations greater than 60 mg/dl. Arginine elicited insulin release at all glucose concentrations and was significantly augmented in the presence of glucose greater than 90 mg/dl. Arginine-stimulated somatostatin release was detectable in the 90-mg/dl glucose group and was significantly augmented in the 120- and 150-mg/dl glucose treatment groups. In conclusion, these studies indicate that glucose modulates the arginine effect on alpha, beta, and delta cells; and alpha cells have a lower threshold to glucose than beta and delta cells. Glucose inhibits arginine-stimulated glucagon release in the absence of a detectable glucose or arginine stimulation of somatostatin release. Thus, glucose appears to play a major role in the control of the putative hormonal influence among the islet cells.
D000818:Animals; D001120:Arginine / Q000494:pharmacology*; D005934:Glucagon / Q000378:metabolism*; D005947:Glucose / Q000494:pharmacology*; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D010179:Pancreas / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013004:Somatostatin / Q000378:metabolism*
D007328:Insulin; D013004:Somatostatin; D005934:Glucagon; D001120:Arginine; D005947:Glucose