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This Article Full Text Full Text (PDF) All Versions of this Article: 68/2/536    most recent biolreprod.102.005900v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Breeveld-Dwarkasing, V.N.A. Articles by Taverne, M.A.M. Search for Related Content PubMed PubMed Citation Articles by Breeveld-Dwarkasing, V.N.A. Articles by Taverne, M.A.M. Agricola Articles by Breeveld-Dwarkasing, V.N.A. Articles by Taverne, M.A.M.

Cervical Dilatation Related to Uterine Electromyographic Activity and Endocrinological Changes During Prostaglandin F₂-Induced Parturition in Cows

^a Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, 3584 CL Utrecht, The Netherlands ^b Department of Obstetrics and Gynaecology, Erasmus University, Rotterdam, The Netherlands ^c Department of Obstetrics and Gynaecology, Swedish University of Agricultural Sciences, Uppsala, Sweden

The temporal relationship between changes in cervical dilatation, uterine electromyographic (EMG) activity, and maternal plasma concentrations of estradiol 17ß (E₂), progesterone (P₄), and 13,14-dihydro-15-keto-prostaglandin-F₂ (PGFM), was investigated in six parturient cows. Calving was induced with a single injection of a synthetic analogue of prostaglandin F₂ (PG) on Day 274 of gestation. Cervical dilatation was measured continuously by measuring the transit time between two implanted ultrasound crystals while at the same time uterine EMG activity was measured through two silver electrodes sutured on the myometrial surface until the expulsive stage of calving had been reached. In blood samples collected at 4-h intervals, starting at the moment of PG injection, the mean plasma E₂ concentration gradually increased and was significantly elevated at 28 h after PG injection. At 4 h after PG treatment, the mean P₄ concentration had dropped significantly and continued to decrease until a value of around 1 ng/ml was reached, where it stayed until the onset of expulsion. Mean plasma PGFM concentrations increased steadily after PG injection, reaching significantly elevated concentrations at 20 h after treatment. In the five cows that delivered calves in anterior positions, uterine EMG activity, expressed as root mean square (RMS in µV), started to increase at a mean interval (± SD) of 13.1 ± 3.7 h following PG treatment. The increase in EMG activity was significantly correlated with changes in plasma PGFM concentrations. In these cows, dilatation of the caudal cervix started after a mean (± SD) interval of 28.5 ± 1.5 h following PG treatment and dilatation progressed at a mean (± SD) rate of 2.25 ± 0.24 cm/h. In one cow with a calf in the posterior position, uterine EMG activity and dilatation started at 15.8 h and 31.8 h, respectively, after induction of calving. We conclude that a predictable sequence of physiological changes occurs around induction of calving, which allows specific timing of future studies on cellular and biochemical changes within the cervix during parturition.

¹ Correspondence: V.N.A. Breeveld-Dwarkasing, Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 7, 3584 CL Utrecht, The Netherlands. FAX: 31 30 2521887; v.n.a.dwarkasing{at}vet.uu.nl