Abstract

Strips of longitudinal and circular muscle were taken from three zones of rabbit uteri shortly before and shortly after parturition. The zones used were the cervical end, the tubal end and a placental site. All six strips were suspended in a common water bath and exposed to the action of the same concentrations of adrenalin chloride, pitocin and pitressin.

Striking differences were observed in the sensitivity of different parts of the uterus to adrenalin and posterior pituitary extract. Most striking was the relative insensitivity of the cervical end to pituitary extract, and relatively great sensitivity to adrenalin.

It is deduced that the complex action of adrenalin is in effect anti-expulsive and thus antagonistic to the action of oxytocin.