EFFECTS OF MATERNAL SUBTOTAL NEPHRECTOMY PRIOR TO MATING ON THE DEVELOPMENT AND FUNCTION OF THE OVINE FETAL KIDNEY
Karen J. Gibson, Bilal M. Karime, YiPing Zhou, Amanda C. Boyce, Eugenie R. Lumbers, Dept of Physiology & Pharmacology, School of Medical Sciences, University of NSW, Sydney 2052.
We hypothesised that fetal kidney development and function would be enhanced if the mother underwent subtotal nephrectomy prior to mating. Previously we had shown that fetal renal function is exquisitely sensitive to acute changes in maternal renal function in late gestation sheep1. Further, uninephrectomized mice have offspring with supranormal nephron numbers2.
Renal function studies were carried out in 9 chronically catheterized fetal sheep aged 127 ± 0.2 days; term=150 days) whose mothers had undergone subtotal nephrectomy (STNxF) and 7 control fetuses aged 127 ± 0.3 days (ConF). The maternal subtotal nephrectomy was carried out at least 2 months prior to mating and consisted of removal of one whole kidney (usually the right) plus ligation of a branch of the renal artery supplying at least one third of the remaining kidney.
Although substantial growth of the remaining maternal kidney had occurred by the time of the fetal experiment, maternal plasma creatinine was higher in the STNx ewes than controls (82 ± 4 compared with 59 ± 3 µmol/L, P=0.001). By contrast, in STNxF plasma creatinine was lower than in ConF (122 ± 5 compared with 156 ± 10 µmol/L, P=0.006). These fetuses also had higher urine flow rates (1.24 ± 0.2 ml/min) and sodium excretion rates (68 ± 6 µmol/min) than ConF (0.63 ± 0.2, P=0.02 and 29 ± 9, P=0.002 respectively). However, there was no significant difference in fetal total kidney weight or in the fetal kidney to body weight ratio between the groups.
It is concluded that maternal subtotal nephrectomy prior to mating resulted in changes in renal function in the STNxF which suggest that these fetuses were exposed to an increased fluid and solute load from the mother.
(1) Lumbers ER, Burrell JH, Stevens AD, Bernasconi C. American Journal of Physiology. 1996;271:R1681-1700.
(2) Averbukh Z, Bogin E, Cohn M, Goren E, Modai D, Rosenmann E, Weissgarten J. Journal of Physiology. 1988;404:31-38.
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