title: Effect of exercise training and carvedilol treatment on cardiac function and structure in mice with sympathetic hyperactivity-induced heart failure.
abstract: The present investigation was undertaken to study the effect of beta-blockers and exercise training on cardiac structure and function, respectively, as well as overall functional capacity in a genetic model of sympathetic hyperactivity-induced heart failure in mice (alpha(2A)/alpha(2C)ArKO). alpha(2A)/alpha(2C)ArKO and their wild-type controls were studied for 2 months, from 3 to 5 months of age. Mice were randomly assigned to control (N = 45), carvedilol-treated (N = 29) or exercise-trained (N = 33) groups. Eight weeks of carvedilol treatment (38 mg/kg per day by gavage) or exercise training (swimming sessions of 60 min, 5 days/week) were performed. Exercise capacity was estimated using a graded treadmill protocol and HR was measured by tail cuff. Fractional shortening was evaluated by echocardiography. Cardiac structure and gastrocnemius capillary density were evaluated by light microscopy. At 3 months of age, no significant difference in fractional shortening or exercise capacity was observed between wild-type and alpha(2A)/alpha(2C)ArKO mice. At 5 months of age, all alpha(2A)/alpha(2C)ArKO mice displayed exercise intolerance and baseline tachycardia associated with reduced fractional shortening and gastrocnemius capillary rarefaction. In addition, alpha(2A)/ alpha(2C)ArKO mice presented cardiac myocyte hypertrophy and ventricular fibrosis. Exercise training and carvedilol similarly improved fractional shortening in alpha(2A)/alpha(2C)ArKO mice. The effect of exercise training was mainly associated with improved exercise tolerance and increased gastrocnemius capillary density while beta-blocker therapy reduced cardiac myocyte dimension and ventricular collagen to wild-type control levels. Taken together, these data provide direct evidence for the respective beneficial effects of exercise training and carvedilol in alpha(2A)/alpha(2C)ArKO mice preventing cardiac dysfunction. The different mechanisms associated with beneficial effects of exercise training and carvedilol suggest future studies associating both therapies.
authors.affiliation: Departamento de Biodinâmica do Movimento do Corpo Humano, Escola de Educação Física e Esporte, Universidade de São Paulo, São Paulo, SP, Brasil.
authors.forename: A
authors.initials: A
authors.lastname: Medeiros
authors.forename: A S
authors.initials: AS
authors.lastname: Vanzelli
authors.forename: K T
authors.initials: KT
authors.lastname: Rosa
authors.forename: M C
authors.initials: MC
authors.lastname: Irigoyen
authors.forename: P C
authors.initials: PC
authors.lastname: Brum
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use*; D000818:Animals; D002227:Carbazoles / Q000627:therapeutic use*; D000077261:Carvedilol; D004195:Disease Models, Animal; D006333:Heart Failure / Q000235:genetics / Q000503:physiopathology / Q000628:therapy*; D051379:Mice; D020297:Mice, Congenic; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010805:Physical Conditioning, Animal; D011412:Propanolamines / Q000627:therapeutic use*; D011897:Random Allocation; D013564:Sympathetic Nervous System / Q000503:physiopathology
chemical_list: D000319:Adrenergic beta-Antagonists; D002227:Carbazoles; D011412:Propanolamines; D000077261:Carvedilol