Stimulus‐secretion coupling in pancreatic acinar cells: influences of external sodium and calcium on responses to cholecystokinin‐pancreozymin and ionophore A23187

Abstract

SUMMARY1. The roles of Na and Ca ions in stimulus-secretion coupling were analysed in the isolated and perfused rat pancreas.2. Partial replacement of NaCl with LiCl produced a diminution in both amylase output and pancreatic juice flow which were induced by 5 m-u. CCK-PZ/ml., and almost normal responses were usually regained immediately after the reintroduction of a standard concentration of NaCl. Nearly total replacement of NaCl with LiCl caused an almost complete inhibition of the responses, although 25 mM-NaHCO3 and 1 mM-NaH2PO4 were still present, and only partial recovery was obtained after the reintroduction of a standard concentration of NaCl.

Inhibitory influence of amino acids on Secretagogues induced exocrine secretion in isolated perfused rat pancreas.

“…WILLIAMS (1975) suggested that Na+ may be important in the early steps of stimulus-secretion coupling, leading to the putative rise in intracellular Ca2+ that triggers pancreatic enzyme release. KANNO et al (1977) also reported the possibility of a quantitative relationship between the amount of amylase released by CCK-PZ or Ca-ionophore A 23187 and extracellular Nat They suggested that cellular mechanism of amylase release requires the dominant activity of a complex composed of carrier molecules bearing one Ca and four Na molecules. Amylase secretion induced by low doses of CCK, which was used in this experiment, was recently shown to be almost dependent of extracellular Ca2+ .…”

“…34, No. 1, 1984 The primary action of CCK-PZ may be to increase carrier-mediated Ca2+ and Na+ influx, which is maintained by the activity of an electrogenic Na pump, and which induces a rise in Ca2+ close to the structures involved in extrusion of zymogen granules (KANNO et al, 1977). Thus, the inhibitory effect of amino acids on the secretory response evoked by CCK-PZ may be attributed to suppression of Ca influx in a stimulus-secretion coupling process.…”

“…Japanese Journal of Physiology A Ca ionophore, A 23187, has been found to elicit release of amylase from pancreatic fragments (EIMERL et al, 1974, WILLIAMS and LEE, 1974, SCHREURS et al, 1976 and the perfused pancreas (KANNO et al, 1977). The following treatments were performed as described previously (KANNO et al, 1977).…”

“…The following treatments were performed as described previously (KANNO et al, 1977). The isolated perfused rat pancreas was perfused with standard Krebs-Henseleit solution for 10 min (1), with Ca-deficient solution for 30 min (2), with the Ca-deficient solution containing l ,ug A 23187/ml for 10 min (3), again with the Ca-deficient solution without A 23187 for 10 min (4), and with a solution containing 2.5 mM Ca without A 23187 (5).…”

Stimulation of amylase and sialic acid releases from dog submandibular gland slices by pilocarpine or high K+ medium: A possible role of calmodulin for their releases.

“…The relationship between Ca2+ and many secretory processes has been extensively studied (DOUGLAS and RUBIN, 1961;DOUGLAS and POISNER, 1963;LESLIE et al, 1976;KANNO et al, 1977;KOELZ et al, 1977;MILLER and NELSON, 1977;WATSON et al, 1979;RUBIN, 1982). Ca2+ antagonists, La3+ and verapamil, block the permeability of cell membranes to Cat+.…”