Erythropoietin production in nephrectomized rats: possible role of the renal erythropoietic factor.

Abstract

Abstract Rats were exposed to 6 hours of hypoxia (0.40 or 0.45 atmospheres of air) starting at 1, 6, 12, 18, or 24 hours after bilateral nephrectomy. A progressive decline in erythropoietin (Ep) levels was observed in the plasma of male animals beginning hypoxia at 1, 6, or 12 hours after nephrectomy, while no activity was detected when hypoxia started 18 or 24 hours after the operation. Intravenous administration of the renal erythropoietic factor (REF) in male rats 18 hours after nephrectomy restored their Ep response to hypoxia to the level of animals exposed to the same hypoxic stimulus starting 1 hour after the operation. It is, therefore, postulated that a decrease in REF activity might be responsible for the decline of the Ep response to hypoxia following nephrectomy. Moreover, male rats were nephrectomized 18 hours after ureter ligation or sham operation. Both groups were subsequently exposed to 6 hours of hypoxia. No significant difference in Ep levels was detected in the plasmas of ureter-ligated and sham-operated animals. These experiments suggest that progression of uremia might not represent the main cause of decrease in the Ep response to hypoxia following nephrectomy.