Creatine during bleeding anemia of rabbits.

: In bleeding induced anemia of rabbits an increase of creatine in the red cells occurred, which in some cases amounted to more than 5-times the normal concentration. In all but one case plasma creatine rose as well. Reticulocytosis, increased O2-consumption of the red cells and an increased level of erythropoietin indicated active erythropoiesis and a shift towards a younger cell population. Whether the rise of red cell creatine is solely due to a higher proportion of young cells remains an open question.