[Involvement of both H1- and H2-receptors in the depressor responses of blood pressure to histamine in the rat (author's transl)].

Histamine caused a dose-dependent fall in blood pressure. This dose-response curve could be shifted to the right by administration of dimethylaminoethyl-N-p-methoxybenzyl-N-alpha-aminopyridine (mepyramine; H1-antagonist). 1-Methyl-([(5-methyl-4-imidazolyl)-2-methylthio]-3-ethyl)-2-thiourea (metiamide; H2-antagonist) alone had no effect on the histamine dose-response curve. The combination of both antagonists caused a further dose-dependent shift to the right. These results found in anaesthetized rats indicate the presence of both histamine receptors in the circulatory system of the rat.