Noise analysis of an ion channel in the cardiac myocyte – Study based on a Markov model

Mechanical contraction of a cardiac muscle cell is related to the electric activation of the plasma membrane. As in the neuron cell, inflow of the Na+ ions across the cell membrane causes electric activation with amplitude of about 100 mV. However, differently from the nerve cell, the action potential lasts a few hundred milliseconds before repolarization. Moreover, several types of K+ channel such as the classical inward rectifier K+ channel, the voltage dependent channel and others are responsible for the formation of the action potential. The mechanism of opening and closing the K+ channels is not thoroughly elucidated. In the present paper, a four state Markov model with one open and three closed states is studied to obtain open and close probabilities of the gates constituting a specific ionic channel. The probability density functions of durations of opening and closing of the channel are also discussed.