Effect of different doses of prostaglandin E-2 on intrauterine pressure and uterine motility during diestrus in experimental cows

Studies in human medicine proved the important role of prostaglandin E-2, w hich stimulates uterine contractions in vivo and in vitro and has been exte nsively used to ripen the cervix around labor. We wanted to demonstrate tha t increasing the dosage of prostaglandin E-2 (1.25 mg, 2.5 mg, 5 mg and 10 mg) provokes an increase in intrauterine pressure and uterine motility in c attle. Five healthy, lactating dairy cows were used as experimental animals for this study. Intrauterine pressure was recorded during the diestrus pha se (1 recording per cow and diestrus phase) by means of a transcervically p laced intraluminal pressure microtransducer. Physiologic uterine motility w as recorded for 30 min, then placebo or one of the prostaglandin E-2 - dosa ges was administered through an indwelling catheter in the jugular vein, fo llowed by a 2-h recording period (eight 15-min periods). Area under the cur ve (AUC), mean amplitude, frequency of pressure waves and intrauterine pres sure were analyzed. Furthermore, we recorded protocols for monitoring heart and respiratory rates and side effects at 9 given examination times. Signi ficant differences were found for the AUC, the mean amplitude and the intra uterine pressure (P less than or equal to 0.05), whereas the number of pres sure waves per 15 min did not differ significantly among treatments. Peak v alues for AUC, mean amplitude and intrauterine pressure were found during t he first 15 min after administration of 10 mg of prostaglandin E-2. Dose-ef fect curves showed that the 2.5 mg dosage provided the optimal ratio betwee n myometrial stimulation and undesirable side-effects. (C) 2000 by Elsevier Science Inc.