Polycythemic Response in Normal Adult Rats to a Nonprotein Plasma Extract from Anemic Rabbits

Experiments are described in which a protein-free extract of plasma obtained from anemic rabbits was injected into healthy young rats. The resulting erythropoietic response was comparable to that induced by hypoxia. The findings suggest that a humoral factor was at work which was capable of disturbing the physiologic mechanisms which establish the equilibrium between red blood cell formation and destruction. The far-reaching significance of these findings is apparent.