Inosine-stimulated insulin release and metabolism of inosine in isolated mouse pancreatic islets.

摘要: Inosine is a potent primary stimulus of insulin secretion from isolated mouse islets. The inosine-induced was totally depressed during starvation, but completely restored by the addition 5 mM-caffeine to medium and partially mM-glucose. Mannoheptulose (3 mg/ml) potentiated effect 10 mM-inosine in islets fed mice. mechanism stimulatory inosine further investigated, it demonstrated that pancreatic contain nucleoside phosphorylase capable converting into hypoxanthine ribose 1-phosphate. at mM concentration increased lactate production content ATP, glucose 6-phosphate (fructose 1,6-diphosphate + triose phosphates) cyclic AMP In starved mice decreased no change could be demonstrated, whereas ATP rose. (10 mM) induced higher than suggesting starvation activities glyceraldehyde 3-phosphate dehydrogenase or other enzymes below this step glycolysis are decreased. Formation negligible. had direct on adenylate cyclase activity islet homogenates. observed changes metabolism mimic what seen when stimulate secretion, as neither nor hypoxanthine-stimulated release, results interpreted supporting substrate-site hypothesis for glucose-induced according which has metabolized beta-cells before initiated.