Humoral Regulation of Erythropoiesis V. Relationship of Plasma Erythropoietine Level to Bone Marrow Activity

The Metabolism of Erythropoietin in Patients with Anemia Due to Deficient Erythropoiesis*

“…After a distribution phase, the serum level declined with a tj of 3 to 5 hours. This tj corresponded well with the decline of serum level of erythropoietin of rats brought from simulated altitude to normal oxygen tensions (8). This suggests that catabolism without significant persistent production is the major factor responsible for the decline in serum erythropoietin after the removal of the stimulus for erythropoietin production.…”

“…The renal clearance rates as calculated from these present studies (Table III) ( 14). Erythropoietically active bone marrow is said to decrease the survival time of the hormone in rats (8) and man (15). In the present study there was no apparent correlation between the tj of erythropoietin survival and the renal or hepatic function of the patient, as evaluated by standard clinical tests, or the erythropoietin level at the onset of the studies or the hemoglobin levels obtained during the study.…”

Erythropoietm and the Kidney

“…Some examples of such instances will be discussed. EP levels in rats exposed to hypoxia rise within 8 h to a peak level determined by the degree of hypoxia and then fall in the following 40 h to a nearly undetectable level [56,103,155]. This fall in the plasma EP level occurs before the RBC mass increases significantly.…”

“…However, it is, at least in part, related to the increase in erythropoiesis which occurs secondary to hypoxia [56]. Other examples of this phenomenon are the plasma EP levels of mice with a congenital marrow defect which are higher than those of comparably anemic nonmutant mice [50] (their EP level normalizes shortly after correction of the marrow defect by transplantation of marrow from nonmutant mice); those of irradiated hypoxic mice are greater than in nonirradiated hypoxic ones [155]; and those of patients with aplastic marrows are greater than in comparably anemic patients with increased erythropoiesis [80,81 ], Stohlman and Brecher [155] suggested that EP is utilized by erythro poietic tissues and consequently the plasma EP level falls as the rate of erythropoiesis accelerates. However, direct attempts to measure the EP clearance rate revealed no increase in the EP clearance rate from the circu lation of animals with increased erythropoiesis [50,56,121].…”

Hematopoiesis in the Grey Collic Dog STUDIES OF THE REGULATION OF ERYTHROPOIESIS

“…It has long been recognized that the initial ESF response to anemia or hypoxia is muted within a period of hours or days (16)(17)(18). It has been postulated that as erythroid proliferation progresses, ESF is utilized by the expanding marrow and serum levels fall.…”