Modeling removal of accumulated potassium from T-tubules by inward rectifier potassium channels

The membrane models of Cannon et al. (1993) and Alberink et al. (1995) for mammalian skeletal muscle fibers are based upon Hodgkin-Huxley descriptions of sodium, potassium delayed rectifier and leak conductances and the capacitive current taking into account fast inactivation of sodium channels. Now inward rectifier and chloride ion currents, sodium-potassium pump and slow inactivation of sodium channels have been inserted. The behavior of the model with respect to resting membrane potential and action potential firing does not differ remarkably from Alberink et al. The model has been used to study the removal of potassium from the T-tubular space. The inward rectifier current significantly contributes to the restoration of the normal potassium concentration after prolonged action potential firing. This may be an important mechanism to avoid muscle fatigue