Hepatic erythropoietin (Ep) production following double partial hepatectomy in the rat.

Double partial hepatectomy (hepx) evokes an elevation in serum erythropoietin (Ep) levels in anephric hypoxic animals when compared to non-hypoxic or sham hepx controls. But this Ep response is significantly lower than that found in singly hepx, anephric hypoxic rats. Double hepx also induces numerous cytological changes in the liver. Extravascular accumulation of fat, fibrous scarring, localized necroses, and multiple abscesses, as well as decreased vascularity, occur following the second hepx. A humoral factor was detected in the serum of these animals that is capable of inducing hepatic Ep production when injected into normal rats 18 hours before nephrectomy and hypoxia. This factor, termed hepatopoietin (Hp), was previously demonstrated in the venous serum of singly hepx rats. The serum from animals subjected to double partial hepx is not as potent in inducing Ep production as the serum from singly hepx animals. The discrepancies noted between the single and double hepx groups is attributed to the necrotic cytological changes described above.