COMPLEXATION OF ARSENIC SPECIES IN RABBIT ERYTHROCYTES

The binding of arsenite, As(III), and arsenate, As(V), by molecules in the intracellular compartment of rabbit erythrocytes has been studied by H-1- and P-31-NMR spectroscopy, uptake of As-73, and ultrafiltration experiments. For intact erythrocytes to which 0.1-0.4 mM arsenite was added, direct evidence was obtained for entry of 76% within 1/2 h and subsequent binding of As(III) by intracellular glutathione and induced changes in the hemoglobin structure (NMR), likely due to binding of As(III). These results were compared with the effect of addition of As(V) on intact erythrocytes and revealed that a smaller amount of As(V) (similar to 25%) enters the cells; the main fraction of As(V) enters the phosphate pathway, depletes ATP, and increases P-i. In contrast, As(III) did not affect the ATP level. Both H-1- and P-31-NMR data indicated striking differences between As(III) and As(V) confirmed by As-73 uptake and binding experiments. meso-2,3-Dimercaptosuccinic acid (DMSA), a dithiol ligand, released glutathione from its arsenite complexes in erythrocytes.