Foetal fluid balance and hormone status following nephrectomy in the foetal sheep

1, The role of the kidneys in the maintenance of normal foetal plasma (FP) composition and hormone concentrations was examined in the present study. F ive ovine foetuses were chronically cannulated and nephrectomized (nephx) a t 100+/-1 days of gestation and maintained for 14 days. These were compared to five intact control foetuses, 2, Four hours after nephx, FP renin concentrations were significantly lower than in control foetuses, By 48 h, renin concentrations in nephx foetuses were below the level of detectability of the assay. Foetal plasma aldostero ne concentrations declined in nephx foetuses, but were not significantly di fferent to those in control foetuses (P = 0.08), 3, During the second week, the nephx foetuses were significantly hypoxic, b ut FP erythropoietin concentrations were not increased. Adrenocorticotropic hormone (ACTH) and cortisol concentrations, when measured on day 14, were not different between the two groups, Adrenocorticotropic hormone levels we re correlated with adrenal weight at post-mortem. 4, Foetal plasma creatinine, magnesium and phosphate concentrations in neph x foetuses increased, eventually reaching values approximately twice that i n controls. Foetal plasma chloride levels decreased continuously in nephx f oetuses, eventually being 23 mmol/L lower than controls. Maternal plasma co mposition was unchanged. 5, Total foetal fluid (amniotic + allantoic) volumes mere reduced when meas ured at post-mortem on day 14 after nephx. The composition of both fluids w as significantly altered in the nephx foetuses compared with controls. 6, Fetuses can sur,ive ill utero for 2 weeks after bilateral nephrectomy, H owever, there are multiple changes in plasma composition that may compromis e foetal survival in the long term.