Electric charges and stability in suspensions of red blood cells.

Abstract

A quantitative study by means of the Michaelis cataphoresis cell of the electric charge of red cells suspended in isotonic sucrose solution has given the following results:

The negative charge of the cells in pure sucrose solution is not permanent, but falls in the course of a few minutes to a point so near zero that it can not be accurately determined. With this fall in potential agglutination of the suspension occurs.

Electrolytes affect the charge of the cells in the same manner as has been observed for their action on the charge of other suspended particles. All electrolytes depress the original negative charge to an isoelectric point and some reverse this negative charge to positive one. With negative cells the degree of change varies with the valency of the cations present. The observation of the effect of valency is, however, complicated by the fact that the cells act as amphoteric electrolytes with the result that hydrolysis may cause the salt of a bivalent metal (CuCl₂) to produce more marked changes than are caused by the salt of a trivalent metal which hydrolyzes less (CeCl₃). Reversal of the negative charge to a positive one is produced by all trivalent ions and occurs with bivalent ions of strongly hydrolyzed salts. These positive charges are permanent and so differ from the negative charge which exists in weak concentrations of all electrolytes.

Stability of the suspension occurs whenever the charge, either positive or negative, is above a certain critical potential. But stability may also occur in the complete absence of any potential in high concentrations of all electrolytes. “Irregular series,” in which a zone of stability is found between two zones of instability, are produced by a reversed strongly positive charge which surpasses the critical potential.