EFFECTS OF NIFEDIPINE ON OVIDUCT MOTILITY AND OVUM TRANSPORT IN RABBITS

Nifedipine (2 mg/kg×3, im) was found to significantly delay egg transport in rabbits 48 h after HCG injection. The mean distance of egg transport (X value)was 65.8±3.0 in nifedipine treated group and 80.0±1.7 in control group (p<0.01). In HCG treated anaesthetized rabbits, nifedipine inhibited the spontaneous oviduct activity and greatly reduced the noradrenaline- and 15-methyl PGF_2α-induced increase in oviduct intraluminal pressure and electrical activity. With isolated ampullary and isthmic circular muscle preparations, nifedipine markedly inhibited the doseresponse curve of noradrenaline. These results suggest that the effect of nifedipine on egg transport may be related to its blocking effect on calcium channel, inhibiting the contraction of oviduct smooth muscle, and/or decreasing the responsiveness of the oviduct to endogenous noradrenaline and PGF_2α.