[The role of carriers of intracellular fixed charges in the regulation of the resting potential of cells with ion pumps].

The living cell is considered as a nonideal phase, surrounded by an anion-permeable membrane in a stationary state. Ionic pumps maintain a nonequilibrium state for Na+ and K+. When assuming the water inside and outside the cell to be in thermodynamic equilibrium and the cell without wall not to resist the hydrostatic pressure difference, it is possible to calculate a membrane potential which strongly depends on the concentration of charged nonpenetrating molecules inside the cell. Living cells with a high resting potential should therefore contain a high inner charge density (nerve cells) or must be resistant to an inner hydrostatic pressure (plant cells). Cells in isotonic solutions with low ionic strength are not able to attain a stationary state. The regulations derived here are applied to the concrete conditions of human red cells.