RESUMEN
Class III anti-arrhythmic drugs (e.g., dofetilide) prolong cardiac action potential duration (APD) by blocking the fast component of the delayed rectifier potassium current (I(Kr)). The block of I(Kr) can result in life threatening ventricular arrhythmias (i.e., torsades de pointes). Unlike I(Kr), the role of the slow component of the delayed rectifier potassium current (I(Ks)) becomes significant only at faster heart rate. Therefore selective blockers of I(Ks) could prolong APD with a reduced propensity to cause pro-arrhythmic side effects. This report describes structure-activity relationships (SARs) of a series of I(Ks) inhibitors derived from 6-alkoxytetralones with good in vitro activity (IC(50) > or =30 nM) and up to 40-fold I(Ks)/I(Kr) selectivity.