Inhibition of Uptake of Radioactive Phosphate by Human Erythrocytes in Vitro

Abstract

Using phosphate labeled with P32 it was found that the rate of uptake of phosphate ions by human erythrocytes in vitro is depressed by the addition of iodoacetic acid (IAA) or NaF. Addition of higher concns. of NaF brings about what appears to be a 2-phase uptake of P32. The initial phase is a process of rapid influx, the rate of which is not affected by a drop in temp. from 37[degree] to 15[degree]C, while the later phase is similar to the depressed chemical mechanism observed in the presence of IAA. A maximum inhibition (to about 20-25% of the normal rate) is observed in the presence of 5 x 10-4 [image] IAA or 2 x 10-2 [image] NaF. Since the glycolytic system in human erythrocytes is completely blocked by these concns. of inhibitors it is inferred that enzymatic reactions other than the known phosphorylating reactions of glycolysis are also involved in the transfer of phosphate into erythrocytes.