The effect of prostaglandin F2 alpha and oxytocin on bovine myometrium in vitro.

Uterine strips were collected from cows during the follicular and the luteal phases as well as from cows with ovarian cysts. The strips were mounted in organ baths and the motility was recorded by a polygraph. After the spontaneous motility of the strips had reached a steady state the test substances PGF2 alpha and oxytocin were added to the bath at three different concentrations. Frequency, amplitude and duration of the spontaneous uterine concentrations were irregular in all strips recorded independent of reproductive stage. The spontaneous activity was most pronounced during the follicular phase. The variation between animals was greatest for cystic cows. PGF2 alpha always increased the activity of the uterus but the response was not dose related above a certain level (50 ng per ml bath fluid). Oxytocin on the other hand had a linear stimulatory effect for increasing doses (0.25, 2.5 and 25 mIU per ml bath fluid).