Cervical Dilatation Related to Uterine Electromyographic Activity and Endocrinological Changes During Prostaglandin F2α-Induced Parturition in Cows
The temporal relationship between changes in cervical dilatation, uterine electromyographic (EMG) activity, and maternal plasma concentrations of estradiol 17β (E 2 ), progesterone (P 4 ), and 13,14-dihydro-15-keto-prostaglandin-F 2α (PGFM), was investigated in six parturient cows. Calving was ind...
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Published in | Biology of reproduction Vol. 68; no. 2; p. 536 |
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Main Authors | , , , , , , |
Format | Journal Article |
Language | English |
Published |
Society for the Study of Reproduction
01.02.2003
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Online Access | Get full text |
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Summary: | The temporal relationship between changes in cervical dilatation, uterine electromyographic (EMG) activity, and maternal plasma
concentrations of estradiol 17β (E 2 ), progesterone (P 4 ), and 13,14-dihydro-15-keto-prostaglandin-F 2α (PGFM), was investigated in six parturient cows. Calving was induced with a single injection of a synthetic analogue of prostaglandin
F 2α (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 E 2 concentration gradually increased and was significantly elevated at 28 h after PG injection. At 4 h after PG treatment, the
mean P 4 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. |
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ISSN: | 0006-3363 1529-7268 |
DOI: | 10.1095/biolreprod.102.005900 |