Erythropoietin production in the isolated perfused kidney

In order to further investigate the dependency of the production of erythropoietin (Epo) on the renal O₂ supply, experiments were carried out in the isolated perfused rat kidney (IPRK). The kidneys were perfused with a substrate enriched Krebs-Henseleit solution containing 60 g/1 bovine serum albumin at a constant perfusion pressure of 100 mmHg. When the kidneys were perfused at an arterial pO₂ of 720 or 150 mmHg (hematocrit 5%), Epo production measured by RIA was very low (0.1-0.2 U/g kidney after 3 h of perfusion). At a pO₂ of 20 mmHg, Epo production increased markedly up to 0.9 U/g kidney. However, the production of Epo was little affected by changes in the hematocrit of the perfusion medium from zero to 40%, even if severe anemia was mimiced. These results indicate that Epo production in the IPRK is mainly under the control of the arterial pO₂.