THE ROLE OF THE KIDNEY IN ERYTHROPOIESIS*

Abstract

Bilateral nephrectomy in dogs abolishes erythropoiesis. Within 3 days normoblasts disappear from the marrow. After nephrectomy Fe turnover is reduced to 0.24 mg/kg/day compared to 0.64 mg/kg/day in normal dogs. Maximal Fe59 incorporation into red cells average 5% after nephrectomy compared to 70% in normal dogs. Although bilateral ureteral ligation resulted in the same elevation of blood urea nitrogen and the same degree of starvation as in the nephrectomized group, erythropoiesis was essentially normal. The erythroblast population of the marrow was maintained. Although the plasma Fe turnover was reduced (0.47 mg/kg/day), it was significantly higher than in the nephrectomized group. Fe59 incorporation into red cells (61.3% was the same magnitude as in the control group. Maintenance of marrow erythroblasts was observed after injection of erythropoietic factor into one bilaterally nephrectomized dog. It is concluded from these data that the cessation of erythropoiesis after nephrectomy cannot be accounted for by urea intoxication and that the kidney is probably the source of an erythropoietic factor.