GASTRIN-STIMULATED CHANGES IN CA2-CELLS DEPENDS ON ADENOSINE 3',5'-CYCLIC-MONOPHOSPHATE LEVELS( CONCENTRATION IN PARIETAL)

Background & Aims: The parietal cell has secretory receptors for hista mine and acetylcholine, whereas the functional nature of the gastrin/c holecystokinin B receptor is controversial. This study in isolated gas tric glands investigates the cholecystokinin B receptor-induced intrac ellular calcium concentration ([Ca](i)) response in enterochromaffin-l ike (ECL) and parietal cells as a function of adenosine 3',5'-cyclic m onophosphate pathways. Methods: The responses of [Ca](i) in ECL and pa rietal cells of perfused rabbit or rat calcium orange-loaded gastric g lands were determined using confocal microscopy. ECL cells were identi fied by position, size, and autofluorescence and parietal cells by pos ition and size. Results: Gastrin (1 mu mol/L) produced an elevation of [Ca]i levels in both ECL and parietal cells. In the presence of 100 m u mol/L cimetidine, the ECL cell response to gastrin was not affected but the [Ca](i) response of the parietal cell was abolished. With dibu tyryl adenosine 3',5' phosphate in addition to cimetidine, the respons e of the parietal cell [Ca](i) to gastrin was restored in both the rat and rabbit. Conclusions: The [Ca](i) response of the parietal but not the ECL cell to the addition of gastrin seems to depend on the presen ce of normal or elevated intracellular adenosine 3',5'-cyclic monophos phate levels. Therefore, H-2 receptor activity may be permissive for t he effect of gastrin on parietal cell function.