Possible regulatory role of histamine in human platelet function examined by thrombin-induced serotonin release.

Abstract

The influence of histamine on human platelet function was studied by thrombin-induced serotonin release. The thrombin-induced 3H-serotonin release was confirmed to be a rapid process which does not require external calcium. Histamine was found to reduce the release of serotonin and the inhibition was abolished when H1-plus H2-antagonists were added together with histamine. H1- and H2-receptor stimulation was examined in two ways, by a combination of histamine with cimetidine or diphenhydramine and by the selective agonists 2-(2-pyridyl)-ethylamine and impromidine. In both instances H1- and H2-stimulation was found to reduce the platelet serotonin release. These results suggest a regulatory role of histamine in the platelet function by stimulation of platelet H1- and H2-receptors.