Red cell stroma protein and hemoglobin can be labeled by feeding C14 lysine during periods of active blood regeneration following anemia.
Stroma proteins are produced and a maximum concentration of the C14 label appears 2 to 3 days earlier than with hemoglobin,—which is to say that stroma building precedes hemoglobin construction.
The concentration of isotope in stroma protein may exceed its concentration in hemoglobin during regeneration following anemia due to blood loss. Diets favorable for hemoglobin regeneration may force the hemoglobin isotope concentration above that of the stroma protein.
In hemolytic anemias great reserves of red cell building material are stored in the body. These stores may modify the curves of isotope concentration in red cells during the recovery periods.
When finally formed, the mature red cells show little or no evidence of participation in general body protein metabolism during their life in the circulation.