Nervous control of pancreatic endocrine secretion in pigs V. Influence of the sympathetic nervous system on the pancreatic secretion of insulin and glucagon, and on the insulin and glucagon response to vagal stimulation

Abstract

Electrical stimulation of the splanchnic nerves in anesthetized pigs was found to stimulate markedly the pancreatic secretion of glucagon. The response pattern was glucose dependent, the glucagon responses at blood glucose concentrations below 4.5 mmol x l-1 being significantly greater than those noted during stimulation at higher concentrations. Insulin secretion was stimulated weakly and variably and only at higher glucose levels. The magnitude of the glucagon response was comparable to that obtained by electrical stimulation of the thoracic vagus nerves with the same frequency. The glucagon response to combined vagal and splanchnic stimulation was nearly identical to the sum of the responses to the two types of stimulation, whereas splanchnic stimulation abolished or reduced the increase in insulin secretion elicited by vagal stimulation. Combined alpha- and beta-adrenergic blockade markedly reduced the glucagon responses to splanchnic stimulation.