Evidence for H2-receptor-mediated inhibition of histamine release from isolated rat mast cells.

Impromidine, an H2-receptor agonist, inhibited the release of histamine from isolated purified rat mast cells evoked by compound 48/80 and acetylcholine. Pyridilethyl-amine (PEA), and H1-receptor agonist, on the other hand, was only slightly effective at very high concentrations. The inhibitory effect of impromidine was blocked by preincubating the cells with cimetidine, but not by chlorpheniramine. The existence of an H2-mediated inhibitory feed-back regulation of histamine release was also suggested by the demonstration of specific binding sites for [3H]-cimetidine in rat mast cell membranes.