Effect of a low-molecular weight serine proteinase inhibitor (camostate) on amylase release from isolated pancreatic acini.

Oral administration of the proteinase inhibitor camostate to rats results in a characteristic regulation of pancreatic enzyme synthesis and release. These effects are thought to be mediated by an endogenous cholecystokinin release in answer to camostate feeding. An additional direct effect of the compound could be exerted directly on the acinar cell. We evaluated in the present study whether the acute or chronic influence of camostate alters the basal or cerulein-stimulated enzyme release from isolated rat acini. Neither basal nor cerulein-induced (10(-12) to 10(-8) M) amylase release from acini of non-pretreated donor rats were influenced in the presence of 5, 50, or 500 microM camostate. After oral feeding of camostate (200 mg/kg b.wt. daily) over 5 days pancreatic growth occurred. In experiments with acini obtained from the camostate-pretreated rats highly significant reductions of the cerulein-induced amylase release were found as compared to controls. Our findings exclude a direct effect of camostate on the secretory process of pancreatic acinar cells. However, after repeated oral pretreatment of donor rats a "desensitization" of acini against cerulein stimulation occurs. This latter effect is ascribed to elevated endogenous cholecystokinin which was released in response to camostate feeding.