Sodium channel gating modes during redox reaction

Background/Aims: Many studies have confirmed that persistent sodium current ( I-NaP) is altered during a redox reaction, but little attention has been paid to transient sodium current ( I-NaT) and its correlation with I-NaP during the redox reaction. The aim of the study was to investigate the effect of the redox states on the correlation between I-NaT and I-NaP in cardiomyocytes. Methods: I-NaT and I-NaP were recorded using whole- cell and cell- attached patch- clamp techniques in guinea pig ventricular myocytes. Results: In whole- cell recordings, dithiothreitol ( DTT, 1 mM) simultaneously increased I-NaT and decreased I-NaP. Hydrogen peroxide ( H2O2, 0.3 mM) increased I-NaP and decreased I-NaT in a time- dependent manner, which were reversed by DTT ( 1 mM). In cell- attached recordings, the increasing of I-NaP and decreasing of I-NaT induced by H2O2 ( 0.3 mM) were similarly recovered by DTT ( 1 mM). H2O2 ( 0.3 mM) prolonged the action potential ( AP) duration of ventricular papillary cells whereas decreased the AP amplitude and maximum rate of depolarization (V-max) in a time- dependent manner, which were reversed by DTT ( 1 mM). Conclusion: These results indicate that the redox states could modulate the sodium channel gating modes in guinea pig ventricular myocytes. Copyright (c) 2007 S. Karger AG, Basel