Effect of exogenous insulin and glucagon on exocrine pancreatic secretion in rats in vivo

Background. The physiological roles of the islet hormones insulin and gluca gon in the control of exocrine pancreatic secretion is not clear. It is sti ll unknown whether these hormones have a stimulatory or an inhibitory effec t on the basal exocrine pancreatic secretion. Methods. Thirty anesthetized rats were stimulated with doses of insulin and glucagon administered by continuous intravenous infusion. Doses varying fr om physiological to supraphysiological were used. Different groups of 5 rat s were given each of these doses. The volume of pancreatic juice and amylas e, lipase and trypsin activity, as well as enzyme output, were measured 0, 20, 40, and 60 min after starting infusion. The insulin, glucagon, and gluc ose levels were determined in serum at 0, 10, 30, and 60 min. Results. In the insulin group, the secreted volume of pancreatic juice incr eases with the maximum dose. All insulin doses results in amylase and lipas e decreased activity. When submaximum and maximum insulin doses are adminis tered, the trypsin activity also decreases. In the glucagon group, the acti vity of lipase and trypsin decreases regardless the dose, whereas the amyla se activity decreases with submaximum acid supra-maximum doses. Conclusion, Both insulin and glucagon affect the basal exocrine pancreatic secretion in vivo when physiological doses are administered.