Ionophore A23187-induced insulin secretion in the isolated, perfused dog pancreas

Perfusion of ionophore A23187 (10 muM) in the isolated dog pancreas resulted in a monophasic release of insulin. Ionophore A23187 (10 muM) failed, however, to elicit insulin secretion when added to calcium deficient (0.1 mmoles/L) perfusate. Simultaneous reintroduction of calcium (1.27 mmoles/L) and discontinuance of ionophore A23187 following calcium deficient periods caused a monophasic secretion of insulin which was quantitatively very similar (41,400 +/- 13,800 muU) to that stimulated by ionophore during normocalcemic perfusion. With reference to the current literature, these results suggest that ionophore A23187 elicits insulin secretion in the perfused dog pancreas preparation by increasing the level of free intracellular calcium, a process which is dependent upon a normal extracellular ionic calcium concentration.