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), an 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.