Inhibition by PGI-2 of myometrial activity in vivo in non-pregnant ovariectomized sheep

Abstract
The effects of PG[prostaglandin]I-salt and PGI2 methyl ester on intrauterine pressure (IUP) and uterine electromyographic activity (EMG) were examined in vivo and non-pregnant ovariectomized sheep. PGI2 salt and PGI2 methyl ester (50-200 .mu.g) reduced significantly the frequency and amplitude of IUP cycles and also inhibited the associated uterine EMG activity. Injections of oxytocin (50 mU) or PGF2.alpha. (2 .mu.g) partly overcame the inhibition of IUP induced by the PGI2 methyl ester. Apparently endogenous PGI2 may be involved in the regulation of uterine activity in sheep.