Voltage-gated sodium (Na) channels, transmembrane proteins that produce the ionic current
responsible for the rapid upstroke of the cardiac action potential, are key elements required
for rapid conduction through the myocardium and maintenance of the cardiac rhythm. The
exquisite sensitivity of the cardiac rhythm to Na channel function is manifest in the
proarrhythmic complications of “antiarrhythmic” Na channel blockade in patients with
myocardial ischemia. More recently, studies of inherited single amino acid substitutions in …