Release of Digestive Enzymes from Isolated Rat Pancreatic Acini Following Muscarinic Stimulation:A Comparative Study with Enzyme Release and Receptor Binding.

Abstract

ABSTRACT-Effect of cholinergic stimulation on the release of digestive enzymes from isolated rat pancreatic acini prepared by collagenase digestion was investigated. The release of enzymes (amylase, chymotrypsinogen, lipase) increased linearly with the time of incubation in the absence of secretagogues. Carbachol, a muscarinic ago nist, induced a remarkable increase in the release of these enzymes. This carbachol stimulated amylase release showed a biphasic curve, and its maximal response was observed at 10-5 M. The release patterns of chymotrypsinogen and lipase were similar to that of amylase. This carbachol-stimulated amylase release was inhibited by atro pine in a dose-dependent manner, with an ED50 value of 1.17 X 10-8 M. Other cho linergic agonists such as methacholine also stimulated the release of these enzymes, and these increases in the release were inhibited by atropine. [2,3-b1[1,4]-benzodiazepine-6-one), on pancreatic acini was also investigated. Based on these results, it has been concluded that isolated rat pancreatic acini have muscarinic receptors and are useful for analyzing the mecha nism of pancreatic enzyme secretion.Pancreatic exocrine secretion is regulated by neural and humoral factors (1-3). Recent de velopment in the techniques to isolate pan creatic acinar cells such as enzyme digestion, chelation and mechanical shearing procedures (2, 4, 5) have facilitated the pharmacological analyses of such regulatory mechanisms on pancreatic exocrine secretion. In fact, pan creatic physiological functions including the re sponsiveness of enzyme secretion to various secretagogues and receptors coupled with pan creatic exocrine function has been clarified (6-9). Amylase secretion has been used as an index for pancreatic exocrine function and for

Characterization of Muscarinic Receptor Subtypes on Rat Pancreatic Acini: Pharmacological Identification by Secretory Responses and Binding Studies

“…Pancreatic acini were prepared according to the procedure de scribed previously [14] with a minor modification [ 15]. Krebs-Henscleit-bicarbonate buffer (110 m V/ NaCI.…”