Regulation of 86Rb+ outflow from pancreatic islets III. Possible significance of ATP.

Antimycin A, oligomycin or anoxia augmented 86Rb fractional outflow rate (FOR) from prelabelled pancreatic islets, whether in the absence or presence of glucose. This effect could be due to activation of a Ca2+-sensitive modality of K+ extrusion, being little affected by tetraethylammonium and almost completely suppressed by quinine. In the presence of the latter drug, antimycin A still provoked a modest increase in 86Rb FOR, the magnitude of which was positively related to the extracellular glucose concentration and which could correspond to a discharge of mitochondrial 86Rb. It is proposed that the decrease in 86Rb FOR evoked by insulinotropic nutrients (e.g. glucose) may depend, to a limited extent, on an increase in ATP generation rate.