Electrophysiological characteristics of cardiac atrial inflow meatus and the implication of the mechanisms of atrial fibrillation

【Author】

WANG Pan,YANG Xin-Chun Beijing ChaoYang Hospital,Capital Medical University,Beijing,China

【Abstract】

<正>Pulmonary veins(PV) and superior vena cava(SVC) composed right and left cardiac atrial inflow meatus together.As special focuses in initiating and maintaining atrial fibrillation(AF),cardiomyocytes in cardiac atrial inflow meatus(PV and SVC) have distinctive electrophysiological characters.In this study,using the wholecell clamp and the conventional microelectrode techniques,we found that comparing with the homologus atrial cardiomyoctyes,the cardiomyoctyes incardiac atrial inflow meatus had longer APD;a few of SVC cardiomyoctyes showed slow response action potentials with automatic activity and some others showed early afterdepolarization (EAD) spontaneously.The PV cardiomyoctyes can be induced second plateau responses easily in common condition, which were the base of EAD.Comparing with the homologus atrial cardiomyoctyes,the cardiomyoctyes of cardiac atrial inflow meatus had smaller I_(to) and I_(K1).We also found that there is some kind of nonselective cation current (INs) in the cardiomyoctyes of atrial intflow meatus.The peak density of INs in the cardiomyoctyes of cardiac atrial inflow meatus was smaller than that in the atrial ones.The agonist or the antagonist of INs could increase or decrease APD.INs in rabbit myocytes was fairly similar to TRPC3 current in electrophysiological property.To sum up,the cardiomyoctyes in cardiac atrial inflow meatus possess the ability of spontaneous activity and to generate EAD.The heterogeneity of APD between the cardiomyoctyes in cardiac atrial inflow meatus and the homologus atrial may facilitate the occurrences of reentry.Both EAD and reentry might be factors initiating and maintaining atrial fibrillation(AF).Transmembrane ionic currents of the cardiomyoctyes in cardiac atrial intflow meatus are key determinants of the arrhythmogenic mechanisms.

【Keywords】

cardiac atrial inflow meatus cardiomyocytes;;nonselective cation current;;atrial fibrillation;;rabbit heart

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