Effects of uterine stimulant drugs on prostacyclin production by the pregnant rat myometrium. I. Oxytocin, bradykinin and PGF2 alpha.

The release of prostacyclin from chopped myometrial fractions of 18-20 day pregnant rats was assayed by inhibition of ADP-induced aggregation of citrated rabbit platelet-rich plasma. Preincubation of myometrial tissue with oxytocin 10 mU/ml increased prostacyclin generation from 2.25 +/- 0.48 (control) to 3.75 +/- 0.73 ng/mg over 15 minutes. Bradykinin 20 microgram/ml also caused a significant increase in myometrial prostacyclin output from 2.26 +/- 0.19 to 4.26 +/- 0.64 ng/mg. PGF2 alpha 1 microgram/ml did not increase prostacyclin release significantly. Pretreatment of myometrial tissue with the phospholipase inhibitor mepacrine significantly reduced the peptide-stimulated release of prostacyclin. The results suggest that prostacyclin production may play an important role in modulating the actions of oxytocin and bradykinin in the pregnant rat myometrium.