Phospholipase A2 activity in pancreatic islets is calcium-dependent and stimulated by glucose

摘要: Phospholipase A2 activity in islet cell homogenates and dispersed cells of the rat was determined using an exogenous radiolabeled phospholipid substrate from E. coli membranes. found to have two pH optima acid or neutral/alkaline ranges. The enzyme at 7.5 calcium dependent responded increasing concentrations with graded increases hydrolysis. Preincubation islets a concentration glucose known elicit maximum rates insulin secretion resulted stable activation phospholipase which assayable homogenates. Glucose stimulated these preparations by as much 220% above control. 2-Deoxy-D-glucose, nonsecretory analogue glucose, did not significant increase activity. sensitive associated membrane-enriched subcellular fraction glucose-stimulated greater than 2-fold higher control stimulation potentiated measured presence high concentrations. also where what may be partly externalized membrane most apparent low These data indicate that possess part localized plasma well other systems, exhibits characteristic properties dependency, sensitivity secretagogue reported for secretory systems.