Electrogenic properties of the sodium pump in a dynamic model of membrane transport.
The general purpose of this theoretical work is to contribute to understand the physiological role of the electrogenic properties of the sodium pump, by studying a dynamic model that integrates diverse processes of ionic and water transport across the plasma membrane. For this purpose, we employ a mathematical model that describes the rate of change of the intracellular concentrations of Na+, K+ and Cl-, of the cell volume, and of the plasma membrane potential (Vm). We consider the case of a nonexcitable, nonpolarized cell expressing the sodium pump; Na+, K+, Cl- and water channels, and cotransporters of KCl and NaCl in its plasma membrane. We particularly analyze here the conditions under which the physiological Vm can be generated in a predominantly electrogenic fashion, as a result of the activity of the sodium pump. A major conclusion of this study is that, for the cell model considered, a low potassium permeability is not a sufficient condition for a predominantly electrogenic generation of the Vm by the sodium pump. The presence of an electroneutral exchange of Na+ and K+ represents a necessary additional requirement.
Hernández
J A
JA
Sección Biofísica, Facultad de Ciencias, Univ. de la República, Iguá esq. Mataojo, 11400 Montevideo, Uruguay.
Chifflet
S
S
D001692:Biological Transport; D002462:Cell Membrane / Q000378:metabolism*; D008954:Models, Biological; D000254:Sodium-Potassium-Exchanging ATPase / Q000502:physiology*
D000254:Sodium-Potassium-Exchanging ATPase