Somatostatin inhibition of insulin and glucagon secretion in rat islet culture: reversal by ionophore A23187.

Both insulin and glucagon release by monolayer cell cultures of newborn rat pancreas were increased when calcium concentration was raised from 1.8 mEq/1 to 7.2 mEq/1. In low calcium medium, the calcium ionophore A23187 (10 mug/ml) enhanced insulin and glucagon secretion. Incubation with somatostatin (1.0 mug/ml), which inhibited hormonal release in a low calcium environment, paradoxically caused augmented insulin and glucagon secretion when A23187 was also present.