KATP channels and ‘border zone’ arrhythmias: role of the repolarization dispersion between normal and ischaemic ventricular regions

In order to investigate the role of KATP channel activation and repolarization dispersion on the ‘border zone’ arrhythmias induced by ischaemia‐reperfusion, the effects of glibenclamide and bimakalim, agents modifying action potential (AP) duration, were studied in an in vitro model of myocardial ‘border zone’. The electrophysiological effects of 10 μM glibenclamide and 1 μM bimakalim (n=8 each), respectively KATP channel blocker and activator, were investigated on guinea‐pig ventricular strips submitted partly to normal conditions (normal zone, NZ) and partly to simulated ischaemic then reperfused conditions (altered zone, AZ). By preventing the ischaemia‐induced AP shortening (P