Cytochalasin B: evidence for a membrane-directed action in B-cells from rat pancreatic islets.

In the presence of cytochalasin B (CCB) concentrations from 50 to 200 mug/ml there is a dose-dependant inhibition of insulin release from isolated rat pancreatic islets. Inhibition is unspecific with respect to glucose, leucine, tolbutamide or theophylline and is reversible. Production of 14CO2 from uniformly labeled D-glucose is decreased. Islets pretreated with an high (200 mug/ml) or low (10 mug/ml) CCB dose release more insulin in response to a subsequent glucose or leucine stimulus in a CCB free medium compared with controls. The data are compatible with a membrane-directed action of CCB.