A renal inhibitor to hepatic erythropoietin [Ep] production

Evidence is presented for the existence of a factor in renal venous blood, evoked by subtotal hepatectomy (hepx), which inhibits the production of Ep in nephrectomized (nephrx) rats exposed to hypoxia. Significant inhibitory activity is not observed in blood obtained from sites other than the renal vein. This inhibitory effect is believed to be due to the action of a specific renal inhibitory factor (RIF) which reduces the extrarenal (hepatic) Ep response to hypoxia indirectly, by decreasing the production or effectiveness of an antagonistic liver principle, the hepatic erythropoietic factor (HEF). The HEF has previously been shown to augment hepatic Ep production following hypoxia in renally-deficient animals. The RIF has no anti-Ep action and its activity is not influenced by the accumulation of metabolic wastes. A mechanism for a renal-hepatic antagonism in the Ep response to hypoxia is hypothesized.