Loss with age in the capacity for erythrogenin production by extrarenal tissues in rats.

: Erythrogenin levels in liver and spleen were compared in young and adult anephric rats exposed to 6h of hypoxia. Hepatic and splenic erythrogenin levels in young nephrectomized rats were significantly higher than those in anephric adults. This lowered ability of the adult rat to elaborate extrarenal erythrogenin may be related to a decrease in selective enzyme production which accompanies the aging process.