Prostaglandin formation by isolated gastric parietal and nonparietal cells of the rat

Abstract

1 Rat gastric cells isolated by pronase and subdivided by Percoll into 3 fractions (F1, F2, F3) were used to study prostaglandin E₂ (PGE₂) formation and, as an indirect measure of parietal cell H⁺ production, [¹⁴C]-aminopyrine uptake. 2 Cells that had not been fractionated, with 20 to 25% parietal cells, contained at 0°C 1.7 ± 0.35 (s.e.mean) ng PGE₂ 10⁸ cells⁻¹. During incubation at 37°C these cells steadily synthesized up to 4.36 ± 0.73 ng PGE₂ 10⁸ cells⁻¹ from endogenous substrate. 3 Indomethacin in concentrations higher than 10⁻⁶moll⁻¹ inhibited this basal formation completely, but 10⁻⁴moll⁻¹ did not reduce the cellular PGE₂ level below 1.4 ± 0.2 ng 10⁸ cells⁻¹. 4 Arachidonic acid in concentrations higher than 10⁻⁵moll⁻¹ evoked an abundant formation of PGE₂, and 10⁻⁴moll⁻¹ built up a plateau of over 7.5 ± 1.65 ng PGE₂ 10⁸ cells⁻¹ within 15 min. 5 PGE₂ formation in cell fractions increased significantly with the number of parietal cells per assay tube. 6 Indomethacin (10⁻⁸ to 10⁻⁴moll⁻¹) did not influence the histamine-stimulated uptake of [¹⁴C]-aminopyrine, while arachidonic acid (10⁻⁵ to 10⁻⁴ moll⁻¹) inhibited this process. 7 PGE₂ formation in response to arachidonic acid was prevented by indomethacin, but the inhibition of aminopyrine uptake by arachidonic acid could not be prevented by indomethacin. 8 The data suggest that isolated gastric cells of the rat sustain constant PGE₂ synthesis in vitro, which is more pronounced in parietal than in mucosal and chief cells. PGE₂ may exert different effects within distinct gastric cell types.