Effects of monovalent cations on sodium permeability of human red cells.

Abstract

AbstractWieth, J. O. Effects of some monovalent cations on sodium permeability of human red cells. Acta physiol. scand. 1970. 79. 76–87.It has been shown previously that monovalent anions of the lyotropic series alter the cation permeability of human red cells. Jn order to determine whether the anion‐induced effects on permeability are inspecific, the effects of an analogous series of monovalent cations were investigated. The permeability to 22Na was the same, whether the predominant cation of a bicarbonate medium was Li, Na, K, Rb, Cs, or choline. In chloride media total substitution of Na with Li did not change the permeability to 22Na, whereas it was doubled after replacement with K, Rb, Cs, or choline. Because both lithium and choline ions stabilize water structure, whereas K, Rb, and Cs arc structure‐breakers, it is not likely that effect of ions is due to an inspecific breaking effect on water structure. A number of distinct differences between the permeability changes caused by anions and by cations indicate that the mechanisms of interaction with the cell membrane must be different for negative and positive ions. Additional information was obtained about the effect of bicarbonate on the cation selectivity of the red cell membrane. Bicarbonate facilitates the permeation of hydrated monovalent cations as lithium and sodium, whereas the permeability to potassium and cesium is reduced. It is suggested that the increased influx is due to the formation of ion pairs (LiCO‐3 and NaCO‐3), penetrating the anion selective membrane much more readily than the cations.