title: Pancreatic acinar cell function: measurement of intracellular ions and pH and their relation to secretion.
abstract: 1. Isolated mouse pancreatic acini were used to investigate the effect of secretagogues on acinar cellular electrolytes and cell pH. The effect of changes in the acid-base status of the incubation medium on acinar cellular electrolytes, cell pH and amylase release were also studied. 2. Carbachol at concentrations of 10(-6) or 10(-5) M was without any effect on the intracellular concentrations of total Na+, Na+ exchangeable with 22Na+, K+ and Cl-, and did not influence cell pH as determined by the DMO method. 3. Changes in pHe achieved by varying the HCO3- concentrations at constant CO2, varying the CO2 concentration at constant HCO3- or by titration of a HCO3-/CO2 free HEPES buffered medium did not influence intracellular electrolyte values. 4. pHi changed linearly with pHe by about 1.2 units/pHe unit change over the pHe range of 7.7--6.5. pHi, however, did not change in response to a change in the CO2 tension when the HCO3- concentration was adjusted to keep pHe at 7.4. 5. Lowering pHe below 7.1 inhibited carbachol and CCK8-stimulated amylase release. By contrast a decrease of pHe to 6.8 was without significant effect on basal and secretagogue increased 45Ca2+ efflux from pancreatic acini. 6. In conclusion the pH sensitivity of amylase release by acinar cells is probably related to changes in pHi. Since Ca2+ mobilization is not affected, the pH sensitive step is probably in the mechanism by which Ca2+ activates the release of zymogen granules contents by exocytosis.
mesh_terms: D000681:Amylases / Q000378:metabolism; D000818:Animals; D002217:Carbachol / Q000494:pharmacology; D004573:Electrolytes / Q000378:metabolism*; D005110:Extracellular Space / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007424:Intracellular Fluid / Q000378:metabolism; D008297:Male; D051379:Mice; D010179:Pancreas / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*
chemical_list: D004573:Electrolytes; D002217:Carbachol; D000681:Amylases