Effect of Isomeres of Triiodothyronine on Erythrokinetics.

Abstract

Summary

Both dextro-triiodothyronine and levo-triiodothyronine produced similar increases in RBC ⁵⁹Fe incorporation in polycy-themic rats when the increased red blood cell mass would have been expected to obviate the response to oxygen need. Single doses of 25; 100 or 250 μg LT₃ and DT₃ produced similar increases in RBC ⁵⁹Fe incorporation in normal rats. The RBC ⁵⁹Fe incorporation was minimally increased at 24 hours and continued to increase 48 and 72 hours following a single dose of LT₃ or DT₃. Plasma obtained from rats following administration of LT₃ or DT₃ failed to demonstrate erythropoietic activity on bioassay in the plethoric mouse, suggesting that increased erythropoietin production is not the mechanism for the augmented erythropoiesis.