Myometrial electrical activity and plasma concentrations of progesterone, estrogens and oxytocin during late pregnancy and parturition in the miniature pig.

摘要: A multifactorial approach was attempted to establish the sequence of events that lead parturition in miniature pig. Uterine electrical activity recorded with chronic electrodes implanted uterine muscle correlated concurrent maternal plasma levels progesterone, estrone, estradiol-1713 and oxytocin. In 7 sows farrowed at normal term period observation covered last 3 weeks pregnancy up end parturition. During late electromyographs (EMGs) consisted irregular episodes ( 3.5 mm duration) which occurred close had been on segments containing a fetus. Empty parts uterus remained relatively inactive. There were no significant changes mean steroid concentrations myometrial over gestation. Plasma oxytocin below 1.2 pU/mI 6 animals sampled between 12 2 days prior Between -24 -10 h before expulsion first piglet, progesterone significantly fallen those estrogens increased. This coincided behavioral sow (nest-building) but this stage similar previous days. It only -9 -4 piglet born pattern EMG5 changed regular phases discharges appeared increasing frequency (7-12/h) all part uterus. At same time peripheral elevated. delivery piglets increased further (18-20/h), their duration being shorter than few hours. Oxytocin reached highest values stage, estrogen already falling 4 nglml sows.