STUDIES ON RELATION BETWEEN ERYTHROPOIESIS AND NUCLEIC ACID METABOLISM IN THE BONE MARROW

Abstract

Using rabbits administered 32P and 59Fe simultaneously or 14C-2-glycine, experimental studies were carried out on the relation between erythropoiesis and nucleic acid metabolism in the bone marrow and the following results were obtained : (1) Results obtained in preparatory experiment revealed that radioactivity due to contamination with 32P was not detected in hemin fraction from blood or the bone marrow. No contamination was demonstrated with 59Fe in DNA and RNA fraction extracted from the bone marrow. There was no free 59Fe in the hemin fraction and no free 32P in the nucleic acid fractions from the bone marrow.(2) Rabbits were given 59Fe-globulinate 6 hours and 32P 4 hours before sacrifice, and hemin and nucleic acids were extracted from their blood and the bone marrow obtained at the time of sacrifice. Two to four rabbits were sacrificed 6, 12, 24, 48 and 96 hours after a single intraperitoneal injection of anemic sheep plasma with high erythropoietin activity (AP) to determine specific radioactivity of the hemin and nucleic acids extracted from peripheral blood or the bone marrow. Prior to sacrifice, each rabbit was given 59Fe and 32P as described above. Specific radioactivity of hemin from the bone marrow was evidently elevated in the rabbits sacrificed 6 hours after AP injection and it remained high as late 96 hours after the injection. Specific radioactivity of hemin from peripheral blood was remarkably lower than that from the bone marrrow, but it was increased from 12 hours after AP administration, attained a peak at 48 hours and remained higher than control value at 96 hours. Specific radioactivities of both DNA and RNA were increased significantly from 12 hours following AP injection and remained in high level until 48 hours.(3) Similar results to those in rabbits with simultaneous use of 59Fe and 32P were obtained in the rabbits administered 14C-2-glycine 4 hours prior to sacrifice.(4) Specific radioactivity of RNA was higher, although it was evidently lower as compared with that in healthy nomal rabbits, in rabbits sacrificed 24 hours after bilateral nephrectomy (Group A) than that in rabbits sacrificed at 54 hours after the operation (Group B) However, specific radioactivity of DNA was equal and remarkably low in these 2 groups of rabbits. In Group A, AP injection immediately after bilateral nephrectomy resulted in significant increase in specific radioactivity both of hemin and RNA. There was no change in specific radioactivity of DNA. In Group B, AP injection 24 hours after the operation resulted in no significant change in specific radioactivities of both hemin and nucleic acids.(5) On the basis of the above described results, relation between erythropoiesis and nucleic acid metabolism in the bone marrow was discussed.