Dietary Zinc and Parturition in the Rat I. Uterine Pressure Cycles

The pattern of uterine pressure cycles following oxytocin infusion was evaluated in near-term pregnant rats as a function of dietary zinc. Pressure cycles were monitored by a pressure transducer and polygraph linked to an intrauterine water-filled latex balloon, inserted on d 19 of gestation, in place of the right cranial fetus and its placenta. Oxytocin infusion on d 22 induced labor in all five zincdeficient rats, but the tracings revealed irregular, poorly synchronized, and/or low amplitude patterns, compared to controls. Excessive abdominal straining was required to accomplish fetal emergence in many instances. The results are interpreted as suggestive of diminished gap-junction formation. Index Entries: Zinc; zinc deficiency; parturition; gap junctions; uterus; estrogen; zinc, and uterine pressure cycles at birth; uterine pressure cycles, pattern of following oxytocin infusion; zinc, effects on parturition.