Insulin secretion induced by alloantigens. Mechanisms of action.

Basal insulin secretion stimulated by allogeneic lymphocyte injection was inhibited by SRIF, diazoxide and verapamil but was not affected by theophylline or imidazole. Glucose stimulated insulin secretion induced by alloantigens was inhibited by imidazole. Maximum insulin secretion was achieved with 2.1 mg/ml theophylline in allogeneized mouse pancreata and with 4.2 mg/ml in control pancreata. Propranolol also blocked allogen-induced glucose-stimulated insulin secretion. Phentolamine enhanced insulin secretion from both experimental groups, but phentolamine plus epinephrine only stimulated insulin secretion in control pancreata. Verapamil, diazoxide and SRIF diminished insulin secretion in both experimental groups. These results suggest that: a) basal insulin secretion induced by alloantigens may be mediated by an increase in calcium translocation, and b) glucose-stimulated insulin secretion induced by alloantigen may be mediated by a rise in B-cell cAMP.