Is the Erythrocyte Permeable to Hydrogen Ions?

The penetration of acids into mammalian erythrocytes may be followed macroscopically by means of the color changes that occur when hemoglobin is converted into acid hematin. 2. The penetration of the acid precedes, rather than follows, hemolysis. In certain cases, penetration may be observed without subsequent hemolysis. 3. Over a considerable pH range, both in the presence and in the absence of NaCl, the rate of acid penetration into the erythrocyte, as inferred from the time of color change, is in semi-quantitative agreement with that predicted for a system permeable to hydroxyl and not to hydrogen ions. There is an entire lack of agreement with the theoretical behavior of such a system when the permeability to the two ions is reversed. The simplest explanation of the observed facts is that the hydrogen ion, like other cations, is unable to enter the erythrocyte easily.