[Effect of hyperglycemia on insulin release from isolated rat pancreatic islets].

We investigated the long-term (24h) influence of high concentration glucose (26.4mmol/L) on insulin release by culturing collagenase isolated rat pancreatic islets in vitro. The cultured islets were morphologically normal by histological examination. Compared with freshly isolated islets, islets cultured in 26.4mmol/L glucose showed higher basal insulin release (P < 0.05). The effect of high glucose was time dependence. When islets preexposed to high glucose medium for 24h were perfused, the basal insulin release was significantly higher than that of freshly isolated islets, the first-phase glucose stimulated insulin release disappeared, and the second-phase was diminished. Islets cultured in high glucose medium showed increased sensitivity to L-arginine. Long-term high concentration glucose could potentiate the arginine-induced release. When added to the culture medium with 26.4mmol/L glucose, Ginseng saponins markedly increased the responsiveness of islets to glucose stimulation, and augmented the sensitivity of incubated islets to additional Ginseng saponins.