The distribution of protons and chloride ions across the erythrocyte membrane of the toad Bufo marinus

Abstract

Proton and chloride ion distributions were measured across the erythrocyte membrane of the toad Bufo marinus over a broad range of extracellular pH values. Intracellular pH was measured using both the freeze–thaw method and the 5,5-dimethyl-2,4-oxazolidinedione method. The results indicate that these ions are passively distributed in a Donnan equilibrium across the erythrocyte membrane. There is, however, a consistent difference between the erythrocyte pH obtained via the freeze–thaw method and that obtained via the 5,5-dimethyl-2,4-oxazolidinedione method. This difference apparently results from a "suspension effect" at the liquid junction potential of the pH electrode encountered when measuring the haemolysate pH.