Atrial reverse remodeling: Restitution of early tachycardia-induced alterations of atrial ion currents after termination of rapid atrial pacing in rabbits

Background and purpose: Studies report on the reversal of electrophysiological parameters altered by atrial tachycardia after cessation of the latter. However, there is no data concerning reversal of tachycardia-induced alterations of ion currents. Reverse remodeling of atrial ion currents (I-Ca,I-L, I-to, I-sus) was studied in our rabbit model of tachycardia-induced electrical remodeling. Methods: Three groups each with four animals were built. Rapid atrial pacing (600/min) for 5 days was applied in all groups. Thereafter, different time intervals (5, 10, 20 days) were awaited before the patch clamp experiments. Results: Similar to Ito remodeling in our model, within 20 days after cessation of atrial tachycardia, time course of Ito reverse remodeling was also U-shaped. In contrast, there was no significant recovery of I-Ca,I-L which was initially reduced by rapid atrial pacing. Conclusion: Relevance of a missing recovery of I-Ca,I-L is likely as this current is closely linked with intracellular calcium handling. (C) 2012 Elsevier Ltd. All rights reserved.