title: Ionic distributions and volume maintenance in human lymphocytes.
abstract: The equilibrium water contents and distributions of Na, K, Cl, Mg, Ca, and inorganic phosphate were studied under a variety of conditions that included 0 degrees C., low external K, ouabain and ATP-depletion. Net exclusion of Na was fully inhibited as manifested by a gain of cellular Na to a level greater than or equal to that in the environment. In none of these conditions did the cells swell in a manner expected in the classical pump-leak, double-Donnan concept of volume maintenance. Moreover, Na, K, Cl, and Mg fail to follow consistently a Donnan equilibrium in cells no longer able to exclude ions. Postulated volume-regulating mechanisms other than outwardly directed Na pumps, such as hydrostatic pressure, a Cl pump, altered charge or osmotic coefficient of proteins, and shrunken and swollen compartments did not explain the results. Therefore, we evaluated the data from the standpoint of a theory of cellular physiology in which cellular ions are adsorbed onto macromolecules. From these concepts and the data presented, a new theory of the maintenance and regulation of cellular volume, in which macromolecular salt-linkages provide a cohesive force, is discussed.
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D001834:Body Water / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D002713:Chlorine / Q000378:metabolism; D004573:Electrolytes / Q000378:metabolism*; D006801:Humans; D008214:Lymphocytes / Q000166:cytology / Q000378:metabolism*; D008274:Magnesium / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism; D011188:Potassium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism
chemical_list: D004573:Electrolytes; D010710:Phosphates; D002713:Chlorine; D000255:Adenosine Triphosphate; D012964:Sodium; D008274:Magnesium; D011188:Potassium; D002118:Calcium