Effects of SZV-2649, a new multiple ion channel inhibitor mexiletine analogue.

The antiarrhythmic and cardiac electrophysiological effects of SZV-2649 that contains a 2,6-diiodophenoxy moiety but lacks the benzofuran ring system present in amiodarone, were studied in mammalian cell line, rat and dog cardiac preparations. SZV-2649 exerted antiarrhythmic effects against coronary artery occlusion/reperfusion induced ventricular arrhythmias in rats and in acetylcholine- and burst stimulation induced atrial fibrillation in dogs. SZV-2649 inhibited hERG and GIRK currents in HEK cells (IC: 342 and 529 nM, respectively).

Cellular electrophysiological effects of the citrus flavonoid hesperetin in dog and rabbit cardiac ventricular preparations.

Recent experimental data shows that hesperetin, a citrus flavonoid, affects potassium channels and can prolong the QT interval in humans. Therefore, in the present study we investigated the effects of hesperetin on various transmembrane ionic currents and on ventricular action potentials. Transmembrane current measurements and action potential recordings were performed by patch-clamp and the conventional microelectrode techniques in dog and rabbit ventricular preparations.

Selective Inhibition of Cardiac Late Na Current Is Based on Fast Offset Kinetics of the Inhibitor.

The present study was designed to test the hypothesis that the selectivity of blocking the late Na current (I) over the peak Na current (I) is related to the fast offset kinetics of the Na channel inhibitor. Therefore, the effects of 1 µM GS967 (I inhibitor), 20 µM mexiletine (I/B antiarrhythmic) and 10 µM quinidine (I/A antiarrhythmic) on I and I were compared in canine ventricular myocardium. I was estimated as the maximum velocity of action potential upstroke (V).

Cardiac electrophysiological remodeling associated with enhanced arrhythmia susceptibility in a canine model of elite exercise.

The health benefits of regular physical exercise are well known. Even so, there is increasing evidence that the exercise regimes of elite athletes can evoke cardiac arrhythmias including ventricular fibrillation and even sudden cardiac death (SCD). The mechanism of exercise-induced arrhythmia and SCD is poorly understood.

Endurance training-induced cardiac remodeling in a guinea pig athlete's heart model.

Besides the health benefits of regular exercise, high-level training-above an optimal level-may have adverse effects. In this study, we investigated the effects of long-term vigorous training and its potentially detrimental structural-functional changes in a small animal athlete's heart model. Thirty-eight 4-month-old male guinea pigs were randomized into sedentary and exercised groups.