Effect of different prostaglandins on intrauterine pressure and uterine motility during diestrus in experimental cows.

Prostaglandins are widely used in herd management due to their luteolytic properties. They have also a direct effect on the myometrium. We hypothesized, that dissimilar prostaglandin preparations would differ as to their contractile effect. Intrauterine pressure was recorded during the diestrus of lactating dairy cows using a transcervically placed intraluminal pressure microtransducer. After recording physiologic uterine motility for 30 min, prostaglandins (dinoprost, DL-cloprostenol, D-cloprostenol) or a placebo was administered intramuscularly, followed by a 2-h recording period. Significant differences were found for the area under the curve (P < or = 0.05) and mean amplitude (P < or = 0.05), whereas the number of spikes per 15 min and the baseline pressure during the last 3 min of every recording period did not differ significantly among treatments. Peak values for area under the curve and mean amplitude were found between 15 and 30 min after administration of DL-cloprostenol, while dinoprost yielded the steadiest plateau from this period until the end of the recording session. These results contrast with those of earlier studies comparing prostaglandins after intravenous administration.