Contribution of Na/Ca transport to the resting membrane potential.
Relations are derived that describe the combined effects of electrodiffusion, the Na/K pump, and Na/Ca transport by carrier on the resting membrane potential. Equations are derived that apply to both steady-state and non-steady-state conditions. Some example calculations from the equations are plotted at different permeability coefficient ratios, PK:PCa:PNa. The equations predict a depolarizing action of Na/Ca transport when more than two Na ions per Ca ion are transported by the carrier. For all permeability ratios examined, a steady state for Ca ions is achieved with at most a few millivolts of depolarization.
D000818:Animals; D001693:Biological Transport, Active; D002118:Calcium / Q000378:metabolism*; D006801:Humans; D008433:Mathematics; D008564:Membrane Potentials; D008954:Models, Biological; D012964:Sodium / Q000378:metabolism*
D012964:Sodium; D002118:Calcium