[The nature of pacemaker activity].
A general equation of the membrane resting potential (RP) has been derived for closed cell membrane (CM) model. It is shown that Na,K-ATPase of cardiomyocytes is in the antielectrogenic phase. A hypothesis is proposed: a pacemaker cell is an excitable cell, which has RP corresponding to the given activity of Na,K-ATPase and non-activated cationic conductivities of CM higher than the activation threshold of Na-channels. The equation of the equipotential levels of the membrane RP on the surface of the cationic conductivities has been derived. It is shown that the substances (e. g. neuromediator) that change the membrane cation permeability are able to depolarize or to hyperpolarize CM. The direction of polarization is dependent on the state of the cell electrogenic system. The following factors promote the hyperpolarizing effect of the magnifying cation permeability substances: 1) high activity of Na,K-ATPase, 2) low background cation permeability of CM (among their number the integrity of CM) and 3) high ratio of the potassium permeability alteration in respect to that of sodium which is evoked by the substance (delta gK/delta gNa).
Kabakov
A Iu
AIu
D001683:Biological Clocks / Q000502:physiology*; D006321:Heart / Q000502:physiology*; D008433:Mathematics; D008564:Membrane Potentials; D009206:Myocardium / Q000201:enzymology; D015222:Sodium Channels / Q000502:physiology; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
D015222:Sodium Channels; D000254:Sodium-Potassium-Exchanging ATPase
O prirode peĭsmekernoĭ aktivnosti.