ELECTROPHYSIOLOGY OF SINGLE CARDIOMYOCYTESISOLATED FROM LEFT ATRIUM AND PULMONARY VEINSOF MYOPATHIC VERSUS HEATHLY HAMSTERS

摘要

Several lines of evidence point to a particularly important role of the left atrium (LA) in initiating and maintaining atrial fibrillation (AF). Left atrial predominance may be related to the location of the pulmonary veins (PV) in the LA. The aim of the present study was to study alterations in the ionic currents and action potentials (AP) of LA-PV cardiomyocytes isolated from Bio 14.6 myopathic Syrian hamsters (41-57 week-old) versus age-matched FIB healthy control hamsters. Whole-cell patch-clamp techniques were used to record AP in current-clamp mode and ionic currents in voltage-clamp mode. The present results show that both myopathic and healthy LA-PV have pacemaker and non-pacemaker cardiomyocytes, but myopathic hamsters have more spontaneously active cardiomyocytes (9/29) than healthy hamsters (3/18). The myopathic myocytes have shorter AP duration (APD) and smaller I_(Ca,L) than the healthy control. Other current such as I_(to), I_K, I_(K1) and I_(Ca,T) have no significant differences. Our results suggest that the LA-PV cardiomyocytes of myopathic hamsters have automatic arrhythmias and the electrophysiological properties are altered (electrical remodeling) in ways that favor the occurrence of reentrant rhythms.