[The contractile effects of oxytocin, prostaglandin F2 alpha and their combined use on human pregnant myometrium in vitro (author's transl)].

The contractile effects of oxytocin, prostaglandin F2 alpha and their combined use on human pregnant myometrium were studied in vitro. A myometrial strip was taken from the lower part of the uterine body in cases of elective caesarean section at term. The specimen was suspended in the Krebs' solution. Tension was isometrically recorded. 1) Evolved tension, 2) interval, 3) duration, 4) area and 5) work of contractions were measured after administration of oxytocin and/or prostaglandin F2 alpha, and compared with those of spontaneous contractions. The fixed one tenth of threshold concentration of prostaglandin F2 alpha and four concentrations of oxytocin from 0.0001 to 0.1 mu/ml were employed for the study of combined use of oxytocin and prostaglandin F2 alpha. Threshold concentrations of oxytocin were 0.001 mu/ml for tension, 0.01 mu/ml for interval, area and work and 1.0 mu/ml for duration, respectively. Those of prostaglandin F2 alpha were not obtained up to 10 microgram/ml for interval but noted at 0.1 microgram/ml for the rest of the parameters. Lowering of the threshold concentration was noted for tension and work in the combined use.