Small signal impedance of heart cell membranes.
The electrical impedance of seven-day ventricular embryonic chick heart cell membranes maintained in tissue culture was measured under voltage clamp using the two-microelectrode voltage-clamp technique. Small sinusoidal perturbations were added to the voltage-clamp potential and the amplitude and phase of the steady-state sinusoidal response in current was recorded as a function of mean clamp potential or perturbing frequency. The experimental results are compared with two models of excitability for heart: the MNT model (McAllister, Noble & Tsien, J. Physiol. (London) 251:1-59, (1975) and the BR model (Beeler & Reuter, J. Physiol. (London) 268:177-210, 1977). The small signal impedance of heart cell membranes, in theory and experiment, shows a resonance near 1 Hz and near the threshold potential. The effect of this resonance is to increase the effective length constant of the membrane for these conditions.
D000818:Animals; D002449:Cell Aggregation; D002462:Cell Membrane / Q000502:physiology; D002478:Cells, Cultured; D002642:Chick Embryo; D004558:Electric Stimulation; D006321:Heart / Q000502:physiology*; D008433:Mathematics; D008564:Membrane Potentials; D008954:Models, Biological; D016276:Ventricular Function