title: Oxidative stress in cardiomyocytes contributes to decreased SERCA2a activity in rats with metabolic syndrome.
abstract: Ca(+) mishandling due to impaired activity of cardiac sarco(endo)plasmic reticulum Ca(2+) ATPase (SERCA2a) has been associated with the development of left ventricular diastolic dysfunction in insulin-resistant cardiomyopathy. However, the molecular causes underlying SERCA2a alterations induced by insulin resistance and related metabolic disorders, such as metabolic syndrome (MetS), are not completely understood. In this study, we used a sucrose-fed rat model of MetS to test the hypothesis that decreased SERCA2a activity is mediated by elevated oxidative stress produced in the MetS heart. Production of ROS and cytosolic Ca(2+) concentration were recorded in left ventricular myocytes using confocal imaging. The level of SERCA2a oxidation was determined in left ventricular homogenates by biotinylated iodoacetamide labeling. Compared with control rats, sucrose-fed rats exhibited several characteristics of MetS, including central obesity, insulin resistance, hyperinsulinemia, and hypertriglyceridemia. Moreover, relative to myocytes from control rats, myocytes from MetS rats exhibited elevated basal production of ROS accompanied by slowed cytosolic Ca(2+) removal, reflected by prolonged Ca(2+) transients. The slowed cytosolic Ca(2+) removal was associated with a significant decrease in SERCA2a-mediated Ca(2+) reuptake and increased SERCA2a oxidation. Importantly, myocytes from MetS rats treated with the antioxidant N-acetylcysteine showed normal ROS levels and SERCA2a-mediated Ca(2+) reuptake as well as accelerated cytosolic Ca(2+) removal. These data suggest that elevated oxidative stress may induce oxidative modifications on SERCA2a leading to abnormal function of this protein in the MetS heart.
authors.affiliation: Departamento de Farmacobiología, Centro de Investigación y de Estudios Avanzados-Instituto Politécnico Nacional, Mexico City, Mexico; and.
authors.forename: Jaime
authors.initials: J
authors.lastname: Balderas-Villalobos
authors.forename: Tzindilu
authors.initials: T
authors.lastname: Molina-Muñoz
authors.forename: Patrick
authors.initials: P
authors.lastname: Mailloux-Salinas
authors.forename: Guadalupe
authors.initials: G
authors.lastname: Bravo
authors.forename: Karla
authors.initials: K
authors.lastname: Carvajal
authors.forename: Norma L
authors.initials: NL
authors.lastname: Gómez-Viquez
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling; D002135:Calcium-Binding Proteins / Q000378:metabolism; D019422:Dietary Sucrose; D004195:Disease Models, Animal; D015536:Down-Regulation; D006946:Hyperinsulinism / Q000097:blood / Q000201:enzymology; D015228:Hypertriglyceridemia / Q000097:blood / Q000201:enzymology; D007333:Insulin Resistance; D008297:Male; D024821:Metabolic Syndrome / Q000097:blood / Q000139:chemically induced / Q000201:enzymology*; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000201:enzymology*; D056128:Obesity, Abdominal / Q000097:blood / Q000201:enzymology; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000187:drug effects; D010766:Phosphorylation; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000378:metabolism; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000378:metabolism*; D018487:Ventricular Dysfunction, Left / Q000201:enzymology / Q000209:etiology; D000099211:Phospholamban
chemical_list: D000975:Antioxidants; D002118:Calcium; D002135:Calcium-Binding Proteins; D019422:Dietary Sucrose; D017382:Reactive Oxygen Species; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D000099211:Phospholamban; C506948:Atp2a2 protein, rat
keywords: calcium; heart; metabolic syndrome; oxidative stress; sarco(endo)plasmic reticulum Ca2+-ATPase 2a