Glucose- and arginine-induced insulin and glucagon responses from the isolated perfused pancreas of the BB-Wistar diabetic rat. Evidence for selective impairment of glucose regulation

Abstract

To investigate whether preferential responsiveness of residual B-cells is a feature of a diabetic state we compared insulin-releasing effects of glucose and arginine in perfused pancreases from moderately diabetic BB-Wistar rats. BB-rats were hyperglycaemic and insulin-dependent but possessed some insulin reserves (6 per cent of pancreatic content of control Wistar rats). Glucose (27.7 mM) failed to release insulin from diabetic pancreases while, conversely, arginine (8 mM) evoked a several-fold increase in insulin secretion. Ratios between responses from diabetic and normal pancreases were 0.01 and 0.29, respectively, when glucose or arginine were used as stimuli. This difference was significant (P less than 0.05, Wilcoxon test). Glucose furthermore failed to exert a time-dependent (= priming) effect on arginine-induced insulin secretion in the diabetic animals. Also A-cell responsiveness to glucose (acute and priming effects) were lost in BB-rats. It is concluded that selective loss of glucose effects on B- and A-cell secretion are associated with the diabetic state of the BB-Wistar rats.