The effects of bradykinin on the contractile activity of the isolated rat ovary

Abstract

Abstract. Studies of ovarian contractility were carried out on 43 rat ovaries maintained in vitro. Eighteen ovaries showed spontaneous motility. In 65 of 155 tests (42%), synthetic bradykinin (3.75–25.0 ng/ml saline) produced sustained increases in ovarian tone, or stimulated phasic contractions. Failure to respond was related to the stage of the oestrous cycle. Sensitivity was highest around ovulation (00.00–04.00 h oestrus), when there were 25 responses in 26 tests, and the linear relationship between the response and the logarithm of the concentration suggested a threshod of 2.9 ng/ml saline. Sensitivity fell later in oestrus, and reached its lowest point in metoestrus (1 reponse in 20 tests). Since the plasma kinin system is activated before ovulation, and the threshold to bradykinin was within reported plasma kinin levels, it seems possible that plasma kinins are involved in contractile processes associated with ovulation.