Effect of histamine on uterine vasculature in rats.

The effects of histamine infusions on the rat uterine vasculature have been studied using the radioactive microsphere technique. Histamine produced a marked uterine vasodilatation which could be partly mimicked by infusion of either the H1-receptor agonist, 2-(2-aminoethyl)pyridine, or the H2-receptor agonist, 4-methyl-histamine. Histamine-induced uterine vasodilatation could only be reduced significantly by administration of a combination of the H1- and H2-receptor antagonists mepyramine and metiamide but not by either antagonist given alone. It was concluded that histamine-induced vasodilatation in the rat uterus is mediated by both H1- and H2-receptors.