An analysis of cardiac sodium channel properties using digital signal processing techniques

Abstract

The properties of single sodium channels in membrane patches from isolated rat ventricular myocytes were analyzed. Both cell-attached and inside-out patch configurations were examined. A digital signal processing method was used which allowed accurate determination of single-channel conductance and mean open time, even in situations where many channels coexisted in the patch. The results show that the cardiac sodium channel has a conductance of 5.3 pS at room temperature, and shows no rectification or saturation in the physiological ranges of ion concentration and membrane potential. The active channels contained in the membrane patch opened and closed independently of each other. A transition probability matrix, which describes transitions between all current levels, can also be generated, analysis of which permits an estimate of individual mean channel open time as well as the degree of coupling between channels. Show more