In vitro interactions of 51Cr in human red blood cells and hemolysates.

The intracellular distribution of radioactivity was studied in normal and sickle erythrocytes labeled with sodium 51Cr chromate. Both types of cells had a higher fraction of 51Cr bound to hemoglobin when labeled in the presence of ACD at a pH of 7.09 than when labeled in the presence of CPD at a pH of 5.96. Citrate at a pH of 5.96 or less entered the red blood cells and decreased the 51Cr binding hemoglobin. Binding of 51Cr to hemoglobin within the red cells was also reduced when the ATP and DPG levels in the red blood cells were elevated. Studies with hemoglobin solution showed that 51Cr binding to hemoglobin was influenced by 2,3-DPG, ATP and citrate.