Hormonal alteration of the response of the rat uterus to catecholamines

Abstract The influence of circulating ovarian hormones on the uterine response to catecholamines in the rat has been studied. Uterine smooth muscles from untreated ovariectomized rats, or from ovariectomized rats under the influence of progesterone, are relaxed by norepinephrine. This response is blocked by β-adrenergic blocking drugs. Samples taken from estrogen-dominated rat uteri, on the other hand, are usually stimulated by norepinephrine, a response which can be prevented by α-adrenergic blocking agents. Thus, the response of the rat uterus to norepinephrine appears to depend on a balance between α and β adrenergic receptors in the myometrium, and this balance is in turn regulated by the ovarian hormones.