Background/aims: Insulin is shown to exert various regulatory effects on the exocrine pancreatic function. We investigated the direct effect of insulin on exocrine pancreatic secretion.
Methods: The effects of insulin on amylase release, 125I-secretin binding and Na(+)- and K(+)-activated adenosine triphosphate phosphohydrolase (Na+,K(+)-ATPase) activity were measured using the isolated rat pancreatic acini.
Results: Insulin potentiated the amylase release elicited by secretin plus cholecystokinin (CCK), but not by either secretin or CCK alone. The potentiating effect of insulin was dependent on the concentration and preincubation time. Insulin had no effect on 125I-secretin binding. Ouabain, a specific Na+,K(+)-ATPase inhibitor, caused a concentration-dependent inhibition of the potentiated secretion by insulin without affecting the secretory response to secretin plus CCK. In membranes prepared from acini treated with insulin, Na+,K(+)-ATPase activity was significantly increased. Similar results were obtained when acini were treated with insulin in combination with secretin plus CCK.
Conclusions: Insulin exerts a direct effect on pancreatic acinar cells and potentiates exocrine secretion elicited by secretin in combination with CCK, in part, by increasing Na+,K(+)-ATPase activity.