Functional measurements on carboxymethylated hemoglobin, a potential blood substitute: effects of sodium chloride on pH values that influence the alkaline Bohr effect.

Abstract

The leakage of chloride from electrodes during measurements of the alkaline Bohr effect of hemoglobin (by the proton release method) amounted to 1-5 mM concentration of the anion depending on the type of electrode employed. This concentration, together with the amount of chloride found to be intrinsically bound to hemoglobin (0.2-0.6 mM), could mask the contribution of chloride to various hemoglobin functions. In addition, the concentration of chloride was found to affect the pH of buffers as measured either with a pH meter or with the dye, cresol red. Thus, for 20 mM phosphate buffer, the pH was lowered almost 0.4 pH units in the presence of 0.30 M chloride. For Tris-acetate buffer, the same concentration of chloride led to an increase in pH of about 0.05 units.