Extrarenal erythropoietin and erythrogenin production in the anephric rat.

Serum erythropoietin and liver erythrogenin activity were studied in nephrectomized, male rats under variations in intensity and length of hypoxic exposure. In the anephric rat, serum erythropoietin levels parallel liver erythrogenin activity under both mild hypoxia (0.42 atm of air) and severe hypoxia (0.35 atm of air) over a 30-h time period. Further studies demonstrate that anephric rats subjected to 24 h of mild hypoxia, at a time when no elevated serum erythropoietin was detected, could once again be stimulated to produce extrarenal serum erythropoietin which was associated with elevated liver erythrogenin activity. These observations suggest that extrarenal erythropoietin production involves an erythrogenin-serum mechanism similar to the one postulated for renal erythropoietin production.