Effects of gastrin on cytosolic free Ca 2+ in individual, acid-secreting rat parietal cells

The effects of gastrin on cytosolic free Ca 2+ ([Ca 2+] i) in single, isolated rat gastric parietal cells were investigated using the fluorescent probe Fura-2 and digital image analysis. [Ca 2+] 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, [Ca 2+] 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 Ca 2+. The results indicate the existence of functional gastrin receptors in a subpopulation of rat parietal cells.