Effect of premature stimulation on fast and slow excitation channels in cultured myocardial cells.
Myocardial cells from chick embryos were cultured using a method which results in cell morphology and action potentials showing greater similarity to that of adult cells than to cells grown with standard methods of culture. The cells were paced by means of rectangular field stimuli (2 msec 2-5 times diastolic threshold). When the stimulus was given during the descending branch of the previous action potential, the action potential developed dissociation between a fast-rise component with short duration and a slow-rise component with longer duration. This dissociation was best in cells with an intermediate rate of rise of the spontaneous action potential and may be caused by different rates of reactivation of the slow and fast membrane excitation channels.
D000200:Action Potentials; D000818:Animals; D002304:Cardiac Pacing, Artificial; D002478:Cells, Cultured; D002642:Chick Embryo; D005318:Fetal Heart / Q000502:physiology*; D008564:Membrane Potentials; D009200:Myocardial Contraction; D009206:Myocardium / Q000166:cytology*