Regulation of pancreatic exocrine secretion in vitro: the action of secretagogues.

Pancreatic acinar cells possess two functionally distinct mechanisms by which secretagogues can increase enzyme secretion. One mechanism is mediated by mobilization of cellular calcium and can be activated by any one of four different classes of receptors. The other mechanism is mediated by cyclic AMP and can be activated by either of two different classes of receptors. In addition to stimulating enzyme secretion, a secretagogue can cause potentiation of secretion, desensitization to the subsequent stimulation caused by the same or other secretagogues as well as residual stimulation of enzyme secretion. Although each class of secretagogue receptors can cause the same final effect, stimulation of enzyme secretion, the existence of multiple classes of receptors and the different mechanisms of action endow the acinar cell with a wide range of patterns of response depending on which of the several classes of receptors are activated.