GESTATION‐DEPENDENT ASPECTS OF THE RESPONSE OF THE OVINE FETUS TO THE OSMOTIC STRESS INDUCED BY MATERNAL WATER DEPRIVATION

Publisher Website
Google Scholar
Abstract
Water deprivation was produced in pregnant sheep by withholding water for 24 h and then giving them 500 ml/day for the subsequent 3 days. All ewes bore chronically cannulated fetuses. Eleven experiments were performed in group-I animals (gestation periods of 107-119 days at maximal stress) and 8 experiments in group-II (126-144 days of gestation). Measurements were made of maternal and fetal plasma osmolalities, fetal urine flow rate and osmolality, amniotic fluid osmolality and fetal plasma antidiuretic hormone (ADH) concentration. The experimental protocol produced a larger increment in maternal and fetal plasma osmolalities in group I than in group II (P < 0.025). For group-I fetuses the relationship between plasma ADH concentration [ADH] and plasma osmolality was log [ADH] = -4.50 + 0.0174 (osmol) which was significantly different from that for group-II fetuses, log [ADH] = -10.46 + 0.0373 (osmol) (P < 0.02). Plasma [ADH] was significantly greater, at a given plasma osmolality, in older (group-II) than younger (group-I) fetuses. For a given value of fetal plasma [ADH], there was a greater reduction in fetal urine free water clearance in older than younger fetuses. Water deprivation of the ewe disturbed the composition of amniotic fluid, and the trend in aminotic fluid osmolality followed the trend in fetal urinary osmolality.

This publication has 0 references indexed in Scilit: