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Studies of the effects of chemical potential, temperature, and metabolic perturbation on static ion contents, kinetics of the approach to equilibrium, and kinetics of ionic self-exchange in human lymphocytes are reviewed. The results contradict the classical concept of cell ion and water physiology, the membrane-osmotic, pump-leak theory, and are re-interpreted by an adsorption model of the cell. In this model, most of cell water exists in a physical state sufficiently ordered to reduce the partition function of dissolved ions, and most of cell potassium is associated with fixed charges on macromolecules. Competing adsorption of potassium and sodium is cooperative and has a critical temperature dependence. The kinetics of the approach to equilibrium are described by a time dependent Ising model. High rates of isotopic self-exchanges of potassium and sodium near the transition point are postulated to result from an increased rate of fluctuations within the ensemble of ion-adsorbing proteins.

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