RADIOACTIVE IRON USED TO STUDY RED BLOOD CELLS OVER LONG PERIODS

Abstract

When the circulating erythrocytes have been tagged by the incorporation of radioactive Fe into their constituent Hb, these cells may be followed in the body for many mos. When disintegration of the red cells occurs, either by aging or trauma, even in the presence of adequate inert storage Fe, the labeled Fe from the liberated Hb is almost immediately re-utilized by new cells such that the total circulating radioactivity is maintained constant. It is not feasible in these expts. to use the Fe isotope in the detn. of the life cycle of the red blood cell. These expts. indicate that the total blood vol. of the dog is maintained at a constant level independent of the state of anemia. As the red cell circulating vol. increases, there is a corresponding drop in the plasma vol. in order to maintain the total circulating blood vol. constant.