%0 Journal Article
%T Reduced Ca2+ transport across sarcolemma but enhanced spontaneous activity in cardiomyocytes isolated from left atrium-pulmonary veins tissue of myopathic hamster
%A Yue-Xia Loh
%A Kuo-Ho Wu
%A Yao-Chang Chen
%A Chih-Hsiung Hsu
%A Jeng Wei
%A Cheng-I Lin
%J Journal of Biomedical Science
%D 2009
%I BioMed Central
%R 10.1186/1423-0127-16-114
%X Whole-cell patch-clamp techniques were used to record AP in current-clamp mode and ionic currents in voltage-clamp mode. The results obtained show that in both healthy and myopathic LA-PV tissue spontaneously discharging cardiomyocytes can be found, but they are more numerous in myopathic (9/29) than in healthy hamsters (4/42, p < 0.05 by ¦Ö2 analysis). Myopathic myocytes have shorter AP duration (APD) with smaller ICa,L and INCX than the healthy control. The currents ITO, IK, IK1 and ICa,T are not significantly different in myopathic versus healthy cells.Our results indicate that in myopathic Syrian hamsters LA-PV cardiomyocytes are more prone to automatic rhythms. Also, they show altered electrophysiologic properties, which may be due to abnormal Ca2+ channels and may account for contractile dysfunction.The Biobreeders strain 14.6 myopathic Syrian hamster had been frequently used as an experimental model for the study of congestive heart failure (CHF) [1-3]. It has been proposed that, because of inherited defects in cytosolic calcium (Ca2+i) reuptake in the sarcoplasmic reticulum (SR) [4,5], myopathic myocytes would be more prone to develop Ca2+i overload and related triggered arrhythmia [6]. In this animal, the evolution of the disease is characterized by (a) an early stage of cellular necrosis (40 to 60 days), (b) a mid-stage of cardiac hypertrophy and ventricular dilation (100 to 300 days), and (c) an end stage of de-compensated heart failure (>360 days).Recently, an increased incidence of atrial fibrillation (AF) has been shown in patients with more advanced CHF [7]. In the left atrium (LA), the pulmonary veins (PVs) are an important source of ectopic beats, which frequently initiate paroxysms of AF. These foci respond to treatment with radio-frequency ablation [8,9]. Previous studies in multiple or single cells from dogs [10,11] and rabbits [12,13] have shown that PVs contain cardiomyocytes, which may be either quiescent or show spontaneous activity. However,
%U http://www.jbiomedsci.com/content/16/1/114