EFFECTS OF GASTRIN ON CYTOSOLIC FREE CA-2+ IN INDIVIDUAL, ACID-SECRETING RAT PARIETAL-CELLS

The effects of gastrin on cytosolic free Ca2+ ([Ca2+]i) in single, isolated rat gastric parietal cells were investigated using the fluorescent probe Fura-2 and digital image analysis. [Ca2+]i was increased by gastrin (100 nM) in ≈30% of the parietal cells, which were identified by using either the fluorescent probe acridine orange or a parietal cell-specific monoclonal antibody. In the dominant pattern observed, [Ca2+]i was elevated 50-150% and returned within 1-2 min to a value 30-60% over the basal, which was sustained until withdrawal of the stimulant or addition of the gastrin inhibitor L-365,260 (1 μM). The second, but not the first phase, was abolished in the absence of extracellular Ca2+. The results indicate the existence of functional gastrin receptors in a subpopulation of rat parietal cells. © 1992 Academic Press, Inc.