Effect of hydrogen peroxide on persistent sodium current in guinea pig ventricular myocytes.
OBJECTIVE
To study the effect of hydrogen peroxide (H2O2) on persistent sodium current (I(Na.P)) in guinea pig ventricular myocytes.


METHODS
The whole-cell, cell-attached, and inside-out patch-clamp techniques were applied on isolated ventricular myocytes from guinea pig.


RESULTS
H2O2 (0.1 mmol/L, 0.5 mmol/L and 1.0 mmol/L) increased the amplitude of whole-cell I(Na.P) in a concentration-dependent manner, and glutathione (GSH 1 mmol/L) reversed the increased I(Na.P). H2O2 (1 mmol/L) increased persistent sodium channel activity in cell-attached and inside-out patches. The mean open probability was increased from control values of 0.015+/-0.004 and 0.012+/-0.003 to 0.106+/-0.011 and 0.136+/-0.010, respectively (P< 0.01 vs control). They were then decreased to 0.039+/-0.024 and 0.027+/-0.006, respectively, after the addition of 1 mmol/L GSH (P<0.01 vs H2O2). The time when open probability began to increase and reached a maximum was shorter in inside-out patches than that in cell-attached patches (4.8+/-1.0 min vs 11.5+/-3.9 min, P<0.01; 9.6+/-1.6 min vs 18.7+/-4.7 min, P<0.01).


CONCLUSIONS
H2O2 increased the I(Na.P) of guinea pig ventricular myocytes in a concentration-dependent manner, possibly by directly oxidating the cell membrane.
Ma
Ji-Hua
JH
Cardio-Electrophysiological Research Laboratory, Medical College, Wuhan University of Science and Technology, Wuhan 430080, China. mjhua@wust.edu.cn
Luo
An-Tao
AT
Zhang
Pei-Hua
PH
D000818:Animals; D004305:Dose-Response Relationship, Drug; D005260:Female; D005978:Glutathione / Q000494:pharmacology; D006168:Guinea Pigs; D006352:Heart Ventricles; D006861:Hydrogen Peroxide / Q000008:administration & dosage / Q000494:pharmacology*; D008012:Lidocaine / Q000494:pharmacology; D008297:Male; D032383:Myocytes, Cardiac / Q000502:physiology*; D015222:Sodium Channels / Q000187:drug effects*
D015222:Sodium Channels; D008012:Lidocaine; D006861:Hydrogen Peroxide; D005978:Glutathione