The coupling of metabolic to secretory events in pancreatic islets: comparison between insulin release and cytosolic redox state.

The cytosolic ratio of free NADH/NAD+ and NADPH/NADP+ was measured in rat pancreatic islets exposed to D-glucose, 2-ketoisocaproate or L-leucine. All nutrients augmented both cytosolic ratios above basal value. There was no parallelism between the magnitude of such changes and the rate of insulin release. It is proposed that the changes in cytosolic redox potential do not represent the essential, or at least sole, determinant of nutrient-induced insulin release.