Evaluation L-type Ca²⁺ Channel Current,Atrial Size And Heart Function In A Canine Atrial Fibrillation Model By Pacing 24 Hours Right Atrium

Object: To study the changes of L-type calcium channel current( Ica-L ),left,right atrium size and heart function in A canine atrial fibrillation model by pacing 24 hours right atrium. Method: Establishing atrial fibrillation model induced by a rapid right atrial pacing(600/min), left,right atrium size and left ventricular ejection fraction were measured after AF 0,4,8,12,24 hours. After 24 hours, single myocytes were isolated by Langendorff perfusion apparatus and enzymatic dissociation. The current of L-type calcium channel was recorded by patch clamp technique in the whole cell mode. Results: Ica-L peak current density was(-4.83±0.30)pA/pF(n=29) in AF group compared with(-6.74±0.29)pA/pF(n=17) in the control group and Ica-L peak current density of AF group was significantly decreased 28.4% (P< 0.05). Left,right atrium transverse diameter gradually increased, but have no significant difference(P>0.05). Left ventricular function significantly decreased 7.48% and 8.81%on AF 12 hour and 24 hour compared with that AF 0 hour. ( P<0.05); Conclusion: After 24 hours atrial fibrillation, Ica-L peak current density of AF group was significantly reduced. This phenomenon may be one of the mechanisms of atrial electrophysiological remodeling in paroxysmal atrial fibrillation. Processing of 24 hours AF can cause atriums enlargement trendency and left ventricular ejection function impairment which probably are one of the mechanisms of atrial structure remodeling in paroxysmal atrial fibrillation.