[Integration of monovalent ion fluxes across plasma membrane under the balanced state: ion gradients and water balance in animal cells].

Interrelationships between monovalent ion transport, the membrane potential, and intracellular ion and water content of an animal cell are analyzed by computation of the balance of ion fluxes across the plasma membrane when the sodium pump and electroconductive channels operate in parallel with NKCC or Na-Cl (NC) symport. The behavior of the system is described in terms of the integral permeability of Cl- channels, the activities of NKCC or NC symport and two dimensionless parameters characterizing the activity of the Na/K pump relative to that of electroconductive channels. The latter two parameters are shown to largely determine the plasma membrane potential and intracellular concentration of K+ and Na+ whereas NC and NKCC symports and the permeability of Cl- channels regulate cell water balance and only slightly influence the intracellular K+/Na+ ratio and membrane potential.