The Life Span of Red Cells in the Rat and the Mouse as Determined by Labeling with

SEVERAL METHODS have been used to determine the life span of rat erythrocytes. Ponticorvo ’ determined the detiterium content of hemin after feeding this nucide to rats and estimated the survival at 100 days. Berlin, Huff and Hennessy2 arrived at tile same estimation by determining tile turn-Over of Fe59 in hemoglobin. In the same laboratory, studies with glycine-C’4-tagged hemoglobin showed a mean survival of 68 days.3 Finch and co-workers deterniined the red cell life span after transfusions of Fe59-tagged cells and fotind it to be from 45 to 50 days.4 With the aid of Cr5 ’ they estimated the average survival time at 50 days.5 Their work is based on the assumption that red cell destruction in the rat is a ran(lofll pheIlOillenOll, an assumption at variance with the observations of Berlin.1 Few recent data on the life span of fllOHSC red cells were found in the literattire. Dod, Bierman alld Sililllkilla determined the life span from the disappearance of sulfhemoglobin from the red cells and found a maximal survival of about 19 days. Burnell, Brickley and Finch4 injected Fe59-tagge