Secretagogue-induced Ca2+ oscillations in isolated canine gastric chief cells.
Agonist-induced changes in cytoplasmic free Ca2+ concentration [( Ca2+]i) of isolated canine gastric chief cells were evaluated by microspectrofluorometry of superfused fura-2 loaded cells. Application of high concentrations of carbachol (CCh, 10(-5) M) or cholecystokinin octapeptide (10(-8) M) resulted in biphasic Ca2+ mobilization comprising an initial large transient followed by a small sustained elevation above the prestimulation level. Submaximal concentrations of CCh (10(-6) M) or cholecystokinin (10(-9) M) led to either a transient series of large amplitude Ca2+ spike(s) or a higher frequency of sustained Ca2+ oscillations of smaller amplitude. Cholecystokinin at 10(-10) M induced only sustained Ca2+ oscillations. Elimination of Ca2+ from the medium had no immediate effect on oscillations indicating an intracellular source of Ca2+. Thus the Ca2+ signalling mode in chief cells is dependent on agonist concentrations.
Tsunoda
Y
Y
Department of Physiology, University of Michigan, Ann Arbor.
Williams
J A
JA
DelValle
J
J
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002217:Carbachol / Q000494:pharmacology; D002478:Cells, Cultured; D003593:Cytoplasm / Q000378:metabolism; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D004492:Edetic Acid; D016257:Fura-2 / Q000494:pharmacology; D005753:Gastric Mucosa / Q000187:drug effects / Q000378:metabolism*; D003012:Microbial Collagenase; D010435:Pepsinogens / Q000378:metabolism*; D012844:Sincalide / Q000494:pharmacology; D013050:Spectrometry, Fluorescence
D010435:Pepsinogens; D002217:Carbachol; D004492:Edetic Acid; D003012:Microbial Collagenase; D012844:Sincalide; D002118:Calcium; D016257:Fura-2