Action of secretagogues on a new preparation of functionally intact, isolated pancreatic acini

¹ Departments of Physiology and Medicine, University of California, and Metabolism Section, Veterans Administration Hospital, San Francisco, California 94143

Isolated pancreatic acini were prepared by a new method from mouse and rat pancreases by digestion with purified collagenase and chymotrypsin followed by mechanical shearing. Acini were structurally similar to those of the intact pancreas, having a normal luminal structure but with the basal acinar cell membranes exposed to the incubation medium. Amylase release in response to both cholinergic analogues and the cholecystokinin analogues caerulein and pentagastrin was comparable to that of the intact pancreas, but was much greater than previously reported for isolated acinar cells. Cholinergic-stimulated release was inhibited by atropine with a K_i value of 1.4 nM which is comparable to other muscarinic receptors. All agonists tested, when added at supramaximal concentrations, produced a submaximal release of amylase even though ATP levels and the release of slowly exchanging ⁴⁵Ca²⁺ were normal or increased. Acini releasing amylase submaximally after being exposed to supramaximal concentrations of carbachol failed to respond to a maximal amount of caerulein or to the Ca²⁺ ionophore A23187. It is concluded that the decreased response (desensitization) is a postreceptor phenomenon and possibly mediated by Ca²⁺ itself.

calcium; amylase; exocrine pancreas; mice

Submitted on March 20, 1978
Accepted on June 19, 1978