Ion Channel and Structural Remodeling in Obesity-Mediated Atrial Fibrillation

Author(s):Show less -

McCauley, Mark D. ^{[1, 2]} ; Hong, Liang ^[1] ; Sridhar, Arvind ^[1] ; Menon, Ambili ^[1] ; Perike, Srikanth ^[1] ; Zhang, Meihong ^[1] ; da Silva, Ivson Bezerra ^[1] ; Yan, JiaJie ^[3] ; Bonini, Marcelo G. ^[1] ; Ai, Xun ^[3] ; Rehman, Jalees ^{[1, 4]} ; Darbar, Dawood ^{[1, 2, 4]}

Affiliation

^[1] Rush Univ, Med Ctr, Dept Med, Chicago, IL 60612 - USA

^[2] Rush Univ, Med Ctr, Jesse Brown VA Med Ctr, Chicago, IL 60612 - USA

^[3] Rush Univ, Med Ctr, Dept Physiol & Biophys, Chicago, IL 60612 - USA

^[4] Univ Illinois, Dept Pharmacol, Chicago, IL - USA

• Document type: Journal article
• Source: CIRCULATION-ARRHYTHMIA AND ELECTROPHYSIOLOGY; v. 13, n. 8 AUG 2020.
• Web of Science Citations: 0

Abstract

Background: Epidemiological studies have established obesity as an independent risk factor for atrial fibrillation (AF), but the underlying pathophysiological mechanisms remain unclear. Reduced cardiac sodium channel expression is a known causal mechanism in AF. We hypothesized that obesity decreases Nav1.5 expression via enhanced oxidative stress, thus reducingI(Na), and enhancing susceptibility to AF. Methods: To elucidate the underlying electrophysiological mechanisms a diet-induced obese mouse model was used. Weight, blood pressure, glucose, F-2-isoprostanes, NOX2 (NADPH oxidase 2), and PKC (protein kinase C) were measured in obese mice and compared with lean controls. Invasive electrophysiological, immunohistochemistry, Western blotting, and patch clamping of membrane potentials was performed to evaluate the molecular and electrophysiological phenotype of atrial myocytes. Results: Pacing-induced AF in 100% of diet-induced obese mice versus 25% in controls (P<0.01) with increased AF burden. Cardiac sodium channel expression,I(Na)and atrial action potential duration were reduced and potassium channel expression (Kv1.5) and current (I-Kur) and F-2-isoprostanes, NOX2, and PKC-alpha/delta expression and atrial fibrosis were significantly increased in diet-induced obese mice as compared with controls. A mitochondrial antioxidant reduced AF burden, restoredI(Na),I-Ca,I-L,I-Kur, action potential duration, and reversed atrial fibrosis in diet-induced obese mice as compared with controls. Conclusions: Inducible AF in obese mice is mediated, in part, by a combined effect of sodium, potassium, and calcium channel remodeling and atrial fibrosis. Mitochondrial antioxidant therapy abrogated the ion channel and structural remodeling and reversed the obesity-induced AF burden. Our findings have important implications for the management of obesity-mediated AF in patients. (AU)

• FAPESP's process: 14/21464-8 - Does Caveolin-1 (Cav-1) modulate arrhythmogenecity by regulating cSrc tyrosine kinase and cardiac gap junction homeostasis? Role of thyroid hormone
• Grantee: Ivson Bezerra da Silva
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate (Direct)