Selective gamma-ketoaldehyde scavengers protect Nav1.5 from oxidant-induced inactivation

The cardiac sodium channel (SCN5A, Na(V)1.5) is a key determinant of electrical impulse conduction in cardiac tissue. Acute myocardial infarction leads to diminished sodium channel availability, both because of decreased channel expression and because of greater inactivation of channels already pres...

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Bibliographic Details
Published in:Journal of molecular and cellular cardiology 2010-02, Vol.48 (2), p.352-359
Main Authors: Nakajima, T, Davies, S S, Matafonova, E, Potet, F, Amarnath, V, Tallman, K A, Serwa, R A, Porter, N A, Balser, J R, Kupershmidt, S, Roberts, 3rd, L J
Format: Article
Language:English
Subjects:
Action Potentials - drug effects
Aldehydes - metabolism
Amines - pharmacology
Cell Line
Free Radical Scavengers - pharmacology
Humans
Ion Channel Gating - drug effects
Ion Channel Gating - ethics
Kinetics
NAV1.5 Voltage-Gated Sodium Channel
Oxidants - toxicity
Oxidative Stress - drug effects
Sodium Channels - metabolism
tert-Butylhydroperoxide - pharmacology
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Summary:The cardiac sodium channel (SCN5A, Na(V)1.5) is a key determinant of electrical impulse conduction in cardiac tissue. Acute myocardial infarction leads to diminished sodium channel availability, both because of decreased channel expression and because of greater inactivation of channels already present. Myocardial infarction leads to significant increases in reactive oxygen species and their downstream effectors including lipoxidation products. The effects of reactive oxygen species on Na(V)1.5 function in whole hearts can be modeled in cultured myocytes, where oxidants shift the availability curve of I(Na) to hyperpolarized potentials, decreasing cardiac sodium current at the normal activation threshold. We recently examined potential mediators of the oxidant-induced inactivation and found that one specific lipoxidation product, the isoketals, recapitulated the effects of oxidant on sodium currents. Isoketals are highly reactive gamma-ketoaldehydes formed by the peroxidation of arachidonic acid that covalently modify the lysine residues of proteins. We now confirm that exposure to oxidants induces lipoxidative modification of Na(V)1.5 and that the selective isoketal scavengers block voltage-dependent changes in sodium current by the oxidant tert-butylhydroperoxide, both in cells heterologously expressing Na(V)1.5 and in a mouse cardiac myocyte cell line (HL-1). Thus, inhibition of this lipoxidative modification pathway is sufficient to protect the sodium channel from oxidant induced inactivation and suggests the potential use of isoketal scavengers as novel therapeutics to prevent arrhythmogenesis during myocardial infarction.
ISSN:0022-2828
1095-8584
DOI:10.1016/j.yjmcc.2009.11.016