title: Age-related changes in cellular electrophysiology and calcium handling for atrial fibrillation.
abstract: This study was to investigate whether or not the dysfunction of atrial repolarization and abnormality of the intracellular Ca(2+) handling protein was augmented with ageing. Four groups of dogs were studied, adult and aged dogs in sinus rhythm (SR) and atrial fibrillation (AF) induced by rapid atrial pacing. We used whole cell patch clamp recording techniques to measure L-type Ca(2+) current in cardiomyocytes dispersed from the left atria. Expressions of the Ca(2+) handling protein were measured by real-time quantitative reverse transcription-polymerase chain reaction and Western blot methods. Cardiomyocytes from old atria showed longer action potential (AP) duration to 90% repolarization, lower AP plateau potential and peak L-type Ca(2+) current densities at both age groups in SR. AF led to a higher maximum diastolic potential, an increase of amplitude of phase 0, decreases of AP duration to 90% repolarization, plateau potential and peak L-type Ca(2+) current densities. Compared to the adult group, mRNA and protein expressions of the L-type calcium channel a1c were decreased, whereas expressions of calcium adenosine triphosphatase were increased in the aged group. Compared to SR group, expressions of Ca(2+) handling protein except for phospholamban were significantly decreased in both age groups with AF. We conclude that these ageing-induced electrophysiological and molecular changes showed that general pathophysiological adaptations might provide a substrate conducive to AF.
authors.affiliation: Department of Cardiology, First Affiliated Hospital, Xinjiang Medical University, Urumqi, China.
authors.forename: Guo-Jun
authors.initials: GJ
authors.lastname: Xu
authors.forename: Tian-Yi
authors.initials: TY
authors.lastname: Gan
authors.forename: Bao-Peng
authors.initials: BP
authors.lastname: Tang
authors.forename: Zu-Heng
authors.initials: ZH
authors.lastname: Chen
authors.forename: Tao
authors.initials: T
authors.lastname: Jiang
authors.forename: Jian-Guo
authors.initials: JG
authors.lastname: Song
authors.forename: Xia
authors.initials: X
authors.lastname: Guo
authors.forename: Jin-xin
authors.initials: JX
authors.lastname: Li
mesh_terms: D000200:Action Potentials; D000375:Aging / Q000378:metabolism / Q000473:pathology*; D000818:Animals; D001281:Atrial Fibrillation / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology*; D002118:Calcium / Q000378:metabolism; D020746:Calcium Channels, L-Type / Q000378:metabolism; D004285:Dogs; D055724:Electrophysiological Phenomena; D006325:Heart Atria / Q000473:pathology / Q000503:physiopathology; D006706:Homeostasis; D009206:Myocardium / Q000378:metabolism / Q000473:pathology; D032383:Myocytes, Cardiac / Q000378:metabolism* / Q000473:pathology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014463:Ultrasonography
chemical_list: D020746:Calcium Channels, L-Type; D012333:RNA, Messenger; D002118:Calcium
keywords: Ageing; Atrial fibrillation; Ca2+ handling proteins; Cellular electrophysiology; L-type Ca2+ current