The in vitro incorporation of radioactive phosphate into rabbit reticulocytes.

Suspensions of rabbit red blood cells containing a high percentage of reticulocytes were obtained by the method of successive daily bleedings. When radioactive phosphorus in the form of inorganic phosphate was added in vitro to such suspensions, the cells took up the labeled phosphate more rapidly than red cell suspensions not containing a high percentage of reticulocytes. The more rapid incorporation of radioactive phosphate into the cells of a rabbit subjected to daily bleedings was not due to the accompanying lipaemia. When Krebs–Ringer – phosphate was substituted for plasma as the suspending medium, the rate of penetration of labeled phosphate into mature red cells or mixtures of red cells and reticulocytes was slower, but when Krebs–Ringer – bicarbonate was substituted the penetration was more rapid. The rate of uptake was decreased by the presence of cyanide (0.005 M) in the suspending medium.