Presence of Plasma Erythropoietin in Hypoxic Rats with or without Kidney(s) and/or Spleen

Abstract

The presence of an erythropoietic factor in the plasma of animals subjected to hypoxic hypoxia has been reported recently by Stohlman and Prentice and Mirand. Additional data from our laboratory bear out a time-concentration relationship of plasma erythropoietin (EPF) in hypoxic hypoxic rats. With knowledge of this time-concentration of EPF, studies were carried out to determine whether this can be altered in absence of the kidney(s) and/or the spleen. Jacobson et al recently reported that bleeding and C0Cl2 administration did not produce circulating erythropoietin in the absence of the kidneys and postulated that the kidney is the site of production of EPF. From our studies the following data are presented: (1) Normal rats placed in a low O2 atmosphere for time periods from 4 to 120 hours reveal definite elevation of plasma erythropoietin to 24 hours, and after 48 hours erythropoietin drops back to normal levels as judged by Fe59 uptake assay using hypophysectomized rats. (2) On the basis of this time-concentration relationship of plasma erythropoietin in hypoxic hypoxic rats, no significant alteration of erythropoietin titers are evident in hypoxic rats with or without kidneys and/or spleen. (3) Hence, neither the kidney nor spleen is the production site of erythropoietin under hypoxic hypoxia.