Effect of reserpinization on insulin secretion in the rat

Reserpine-induced supersensitivity to the insulin-releasing action of a beta-adrenergic agonist, isoprenaline, and of glucose was studied in vivo and in vitro. The subcutaneous injection of rats with reserpine (0.05 to 10 mg kg-1) enhanced the action of isoprenaline on insulin secretion. ED50 of isoprenaline for insulin secretion was changed little after reserpinization, whereas maximum effect of the beta-agonist was enhanced by pretreating rats with reserpine. Glucose-stimulated insulin secretion was also enhanced in the reserpinized rats. Pancreases isolated from the reserpinized rats secreted more insulin in response to phentolamine in the presence of glucose and isoprenaline. These results suggest that the supersensitivity in insulin secretion induced by reserpine may be non-specific.