Sustained Erythropoietin Production in Nephrectomized Rats Subjected to Severe Hypoxia

Abstract

S ummary . The present studies indicate that rats of both sexes subjected to a hypoxic stimulus of severe degree (0.35 atmospheres of air) show sustained production of erythropoietin (Ep) up to 30 hr after bilateral nephrectomy. In contrast to this phenomenon, the Ep response to relatively mild hypoxia (0.45 atmospheres of air) declines rapidly and is totally abolished within either 12 hr (females) or 24 hr (males) after nephrectomy. In this regard, since orchidectomized rats and intact female animals show a similar decline of the Ep response curve, it seems likely that androgens play a major role in the above sex difference. The sustained Ep production in both anephric rodents exposed to severe hypoxia and ureter‐ligated rats subjected to mild hypoxic stimuli suggest that extrarenal Ep production is largely independent of the development of uraemia. It is postulated that the biogenesis of Ep in anephric rodents is mediated by either the triggering of extrarenal sources of Ep and/or erythrogenin (Eg) induced by severe hypoxia or activation of residual renal Eg following relatively mild hypoxic stimuli.