The uterine motility in cattle during late pregnancy, labor and puerperium. II. Drug modification

The uterine effects of oxytocin, the prostaglandins dinoprost and cloprostenol as well as clenbuterol, ergometrin, xylazine and Utrorale were investigated in 8 cows during late pregnancy, parturition and early puerperium (until 4th day p. p.). Uterine motility was measured by means of pressure microsensors and electrodes which were surgically implanted 3 to 4 weeks before parturition. Hysterograms were characterized by means of pressure amplitude, frequency and duration of uterine contractions and also by electromyography. Oxytocin (2-5 IE) given intravenously always provoked strong uterine contractions until the 4th day p.p. From the prostaglandins examined during early puerperium only dinoprost (15 mg i.v.) produced uterotonic effects, while the synthetic analogue cloprostenol (0.25 mg i.v.) had a weak stimulatory activity only on day 1 p.p. Both prostaglandins were ineffective when injected intramuscularly. Clenbuterol (0.3 mg i.v.) a beta 2-mimetic compound effectively induced long lasting tocolysis during parturition, which could be abolished by oxytocin. Xylazine (10 mg i.v.) was able to significantly increase uterine motility during late gestation. Following intravenous administration of ergometrin (1 and 10 mg), bunitrolol (1-16 mg) and Utrorale (0.1-4 ml) including its compounds oleum sabinae, oleum terebinthinae, balsamum copaivale and Styrax no uterokinetic activity was recorded at any time.