Direct calcium-stimulated release of glucagon from the isolation perfused rat pancreas and the effect of chemical sympathectomy.

"Staircase" increments of calcium (from 0.5 to 15 mEq/L) were added to the perfused rat pancreas in the absence of glucagon secretogogues. Large spikes of glucagon release resulted, particularly at the small and large calcium concentrations. Insulin secretion was undetectable. Selective destruction of peripheral adrenergic neurons by pretreatment of the rats with 6-hydroxydopamine reduced the basal glucagon secretion to about 50% and specifically suppressed the calcium-induced glucagon release at the lower calcium steps. The response to a subsequent stimulation by arginine/calcium was not inhibited. Results suggest that glucagon secretion is modulated by a stimulant effect of the pancreatic adrenergic nerves (norepinephrine?) and that calcium in part positively affects release by permitting this neural stimulation.