Late Sodium Current in Atrial Cardiomyocytes Contributes to the Induced and Spontaneous Atrial Fibrillation in Rabbit Hearts

Abstract: Increased late sodium current (INa) induces long QT syndrome 3 with increased risk of atrial fibrillation (AF). The role of atrial late INa in the induction of AF and in the treatment of AF was determined in this study. AF parameters were measured in isolated rabbit hearts exposed to late INa enhancer and inhibitors. Late INa from isolated atrial and ventricular myocytes were measured using whole-cell patch-clamp techniques. We found that induced-AF by programmed S1S2 stimulation and spontaneous episodes of AF were recorded in hearts exposed to either low (0.1–3 nM) or high (3–10 nM) concentrations of ATX-II (n = 10). Prolongations in atrial monophasic action potential duration at 90% completion of repolarization and effective refractory period by ATX-II (0.1–15 nM) were greater in hearts paced at slow than at fast rates (n = 5–10, P
Source: Journal of Cardiovascular Pharmacology - Category: Cardiology Tags: Original Article Source Type: research