How sex hormones and oxytocin together affect contractions of human uterus muscle at term

Superfusion with progesterone plus oxytocin or estradiol reduced contraction activity in human myometrium.

• Increased frequency of contractions was observed with progesterone plus oxytocin, progesterone plus estradiol, and their combination compared to buffer alone.
• Decreased activity area and duration of contractions were noted with hormonal superfusion compared to buffer.
• Higher concentrations of progesterone (5 micrograms/mL) plus oxytocin and progesterone plus estradiol elevated uterine tonus.
• Lower concentrations of progesterone (0.5 microgram/mL) plus estradiol or their combination with oxytocin did not significantly affect tonus.
• Progesterone and estradiol may directly influence uterine excitability and regulate the sensitivity to oxytocin.

Simplified