Effect and mechanism of action of histamine on rat uterine contractility in relation to sex steroid hormones

Abstract

In this work the effect of histamine on uterine contractility in non­ pregnant mature rats was investigated. Also through which type of receptors it acts and its relation to sex steroid hormones. Finally, the involvement of Ca2+ and K+ channels in the mechanism of action of histamine was examined. The experiments were classified into four groups non pregnant group, ovariectomized group, ovariectomized progesterone -replaced group and ovariectomized oestrogen-replaced group, each group contained 6 mature non-pregnant rats.

In all groups, histamine had a relaxant effect on the spontaneous contractility of rat uterine strips. This inhibitory effect seems to be mediated via H2 receptors. Both oestrogen and progesterone augmented the relaxant effect of histamine.

In The control group only the Ca2+ and K+ channel blocker were first applied alone then followed by histamine. We find that the Ca2 channel do not seem to be involved in the mechanism of action of histamine, but histamine seems to act partially via K+ channels.