Interaction of ranitidine and famotidine with guinea pig-isolated parietal cells

The inhibitory effects of the histamine H2-receptor antagonists, ranitidine and famotidine on histamine-stimulated gastric acid secretion have been studied in guinea pig isolated, enriched parietal cells using the 14C-aminopyrine accumulation technique. The 14C-aminopyrine accumulation curves in response to histamine were shifted towards the right in a parallel fashion by ranitidine, and in a nonparallel fashion by famotidine. The inhibitory effect of ranitidine, but not that of famotidine, was readily reversed by washing the parietal cells. It is concluded that the histamine H2-receptors in guinea pig parietal cells are blocked competitively and reversibly by ranitidine, but noncompetitively and partially reversibly by famotidine.