Utero-inhibin: a new substance inhibiting uterine contraction, isolated from amniotic fluid

Amniotic fluid was collected from women in the 2nd trimester of their gravidity by amniocentesis and its effect on the isolated pregnant rat uterine preparation investigated. It was demonstrated that some of the amniotic fluid components partially purified by using the combination of various separation techniques stimulated, while others inhibited the contractions of the isolated rat uterine preparation. The inhibitory component, called utero-inhibin also inhibited the spontaneous contractions as well as the basal tone of the isolated rat intestinal preparation and those of the isolated human pregnant myometrium preparation. It is speculated that the inhibitory factor might play a physiological role in maintaining the resting state of human uterus during pregnancy.