Effect of oxytocin on the contractility of the human oviduct in vivo

The effects of oxytocin, administered by either rapid or slow iv injection, on fallopian tube contractility were studies. Single iv doses were shown to consistently induce several contractions with a mean intensity of 10 mm Hg and hypertonia of varying duration. The oxytocin-induced bursts were synchronous in both tubes while normal spontaneous contractions are asynchronous. The tubes showed a high sensitivity to even small doses of oxytocin. The minimum does (threshold dose) of oxytocin eliciting tubal response in the patients was 250 mU. The intensity and duration of oxytocin-induced contractions were dose-dependent with the maximal responses obtained with oxytocin doses of 5 IU or less. The highest sensitivity was during the proliferative stage of the ovarian cycle. Continuous iv infusions of oxytocin ranging from 20 to 40 mU/minute increased tubal activity during administration. It was determined that the sensitivity of the human fallopian tube to oxytocin was higher than that of the nongravid uterus and lower than that of the mammary gland during lactation.