The effect of arginine, vasotocin and ovarian steroids on uterine contractility in the snapping turtle, Chelydra serpentina

The contractility of uterine segments was studied in vitro during different phases of the ovarian cycle in relation to the plasma levels of progesterone and estradiol, 17β. 1.2. Treatment of the uterine segments with arginine vasotocin (AVT) increased contractility (amplitude and frequency) and decreased latency between contractions, except during the early postovulatory phase when the corpora lutea were steroiriogenically active.2.3. Pretreatment of turtles with progesterone decreased contractility during the early postovulatory phase but had no effect during the remainder of the ovarian cycle.3.4. Pretreatment with estradiol-17β increased contractility during all phases except early postovulatory when there was no effect on amplitude.4.5. Total time of rhythmic contractions increased significantly (anterior vs posterior uterine segments P < 0.95) throughout the ovarian cycle. It was lowest during the early postovulatory phase (P < 0.05).