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Effect of exercise training and carvedilol treatment on cardiac function and structure in mice with sympathetic hyperactivity-induced heart failure

MEDEIRO, A.; VANZELLI, A.S.; ROSA, K.T.; IRIGOYEN, M.C.; BRUM, P.C.
Fonte: Associação Brasileira de Divulgação Científica Publicador: Associação Brasileira de Divulgação Científica
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
46.33%
The present investigation was undertaken to study the effect of β-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 (α2A/α2CArKO). α2A/α2CArKO 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 α2A/α2CArKO mice. At 5 months of age, all α2A/α2CArKO mice displayed exercise intolerance and baseline tachycardia associated with reduced fractional shortening and gastrocnemius capillary rarefaction. In addition...

Aerobic exercise training improves skeletal muscle function and Ca(2+) handling-related protein expression in sympathetic hyperactivity-induced heart failure

Bueno Junior, C. R.; Ferreira, J. C. B.; Pereira, M. G.; Bacurau, Aline Villa Nova; Brum, Patricia Chakur
Fonte: AMER PHYSIOLOGICAL SOC Publicador: AMER PHYSIOLOGICAL SOC
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
46.54%
Bueno CR Jr, Ferreira JC, Pereira MG, Bacurau AV, Brum PC. Aerobic exercise training improves skeletal muscle function and Ca(2+) handling-related protein expression in sympathetic hyperactivity-induced heart failure. J Appl Physiol 109: 702-709, 2010. First published July 1, 2010; doi: 10.1152/japplphysiol.00281.2010.-The cellular mechanisms of positive effects associated with aerobic exercise training on overall intrinsic skeletal muscle changes in heart failure (HF) remain unclear. We investigated potential Ca(2+) abnormalities in skeletal muscles comprising different fiber compositions and investigated whether aerobic exercise training would improve muscle function in a genetic model of sympathetic hyperactivity-induced HF. A cohort of male 5-mo-old wild-type (WT) and congenic alpha(2A)/alpha(2C) adrenoceptor knockout (ARKO) mice in a C57BL/6J genetic background were randomly assigned into untrained and trained groups. Exercise training consisted of a 8-wk running session of 60 min, 5 days/wk (from 5 to 7 mo of age). After completion of the exercise training protocol, exercise tolerance was determined by graded treadmill exercise test, muscle function test by Rotarod, ambulation and resistance to inclination tests, cardiac function by echocardiography...

Adaptations in autonomic function during exercise training in heart failure

Negrão, Carlos Eduardo; Middlekauff, Holly R.
Fonte: SPRINGER Publicador: SPRINGER
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
56.51%
Although neurohumoral excitation is the hallmark of heart failure (HF), the mechanisms underlying this alteration are not entirely known. Abnormalities in several systems contribute to neurohumoral excitation in HF, including arterial and cardiopulmonary baroreceptors, central and peripheral chemoreceptors, cardiac chemoreceptors, and central nervous system abnormalities. Exercise intolerance is characteristic of chronic HF, and growing evidence strongly suggests that exercise limitation in patients with chronic HF is not due to elevated filling pressures or inadequate cardiac output during exercise, but instead due to skeletal myopathy. Several lines of evidence suggest that sympathetic excitation contributes to the skeletal myopathy of HF, since sympathetic activity mediates vasoconstriction at rest and during exercise likely restrains muscle blood flow, arteriolar dilatation, and capillary recruitment, leading to underperfused areas of working muscle, and areas of muscle ischemia, release of reactive oxygen species (ROS), and inflammation. Although controversial, either unmyelinated, metabolite-sensitive afferent fibers, and/or myelinated, mechanosensitive afferent fibers in skeletal muscle underlie the exaggerated sympathetic activity in HF. Exercise training has emerged as a unique non-pharmacological strategy for the treatment of HF. Regular exercise improves functional capacity and quality of life...

Exercise training delays cardiac dysfunction and prevents calcium handling abnormalities in sympathetic hyperactivity-induced heart failure mice

Medeiros, Alessandra; Rolim, Natale P. L.; Oliveira, Rodrigo S. F.; Rosa, Kaleizu T.; Mattos, Katt Coelho; Casarini, Dulce E.; Irigoyen, Maria Claudia; KRIEGER, Eduardo M.; Krieger, Jose Eduardo; Negrão, Carlos Eduardo; Brum, Patricia C.
Fonte: AMER PHYSIOLOGICAL SOC Publicador: AMER PHYSIOLOGICAL SOC
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
46.49%
Exercise training (ET) is a coadjuvant therapy in preventive cardiology. It delays cardiac dysfunction and exercise intolerance in heart failure (HF); however, the molecular mechanisms underlying its cardioprotection are poorly understood. We tested the hypothesis that ET would prevent Ca2+ handling abnormalities and ventricular dysfunction in sympathetic hyperactivity-induced HF mice. A cohort of male wildtype (WT) and congenic (alpha 2A/alpha 2C)-adrenoceptor knockout ((alpha 2A/alpha 2C)ARKO) mice with C57BL6/J genetic background (3-5 mo of age) were randomly assigned into untrained and exercise-trained groups. ET consisted of 8-wk swimming session, 60 min, 5 days/wk. Fractional shortening (FS) was assessed by two-dimensional guided M-mode echocardiography. The protein expression of ryanodine receptor (RyR), phospho-Ser(2809)-RyR, sarcoplasmic reticulum Ca2+ ATPase (SERCA2), Na+/Ca2+ exchanger (NCX), phospholamban (PLN), phospho-Ser(16)-PLN, and phospho-Thr(17)-PLN were analyzed by Western blotting. At 3 mo of age, no significant difference in FS and exercise tolerance was observed between WT and (alpha 2A/alpha 2C)ARKO mice. At 5 mo, when cardiac dysfunction is associated with lung edema and increased plasma norepinephrine levels...

Efeito do treinamento físico na cardiomiopatia induzida por hiperatividade simpática em camundongos com ablação dos receptores alpha 2A/alpha 2C- adrenérgicos; Effect of exercise training on cardiomyopathy induced by sympathetic hiperactivity in mice lacking a2A/a2C- adrenoceptors

Medeiros, Alessandra
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 16/08/2006 Português
Relevância na Pesquisa
46.5%
Os receptores a2-adrenérgicos pré-sinápticos (a2 AR) regulam a função cardiovascular através da inibição da liberação do neurotransmissor no terminal nervoso simpático. Recentemente, foi publicado que a ablação dos subtipos a2A e a2C -AR em camundongos (KO) leva a hiperatividade simpática com evidências de disfunção cardíaca aos 4 meses de idade. Esses camundongos constituem um modelo experimental para o estudo dos tratamentos farmacológicos e não farmacológicos para a prevenção e o tratamento da insuficiência cardíaca. Nós estudamos se o treinamento físico melhoraria a função cardíaca e a expressão de proteínas cardíacas envolvidas no controle do Ca2+ intracelular em camundongos KO. Métodos e Resultados: Camundongos controle e KO foram estudados dos 3 aos 5 meses, onde a cardiomiopatia está em estágio inicial, e divididos aleatoriamente em treinados e sedentários. O treinamento físico (TF) foi realizado com natação, 1 hora por dia, 5 vezes por semana, por 8 semanas. A pressão arterial e a freqüência cardíaca de repouso (FC) foram medidas por pletismografia de cauda. A fração de encurtamento (FS) por ecocardiograma. A tolerância ao esforço físico por teste progressivo em esteira rolante. O tônus simpático cardíaco foi estimado por bloqueio farmacológico dos receptores muscarínicos e adrenérgicos com atropina na presença ou ausência do antagonista b-adrenérgico propranolol. O diâmetro dos cardiomiócitos e a fração de colágeno cardíaco por microscopia óptica. A expressão das proteínas cardíacas: bomba de Ca2+ do retículo sarcoplasmático (SERCA2)...

Efeito do treinamento físico nas adaptações estruturais cardíacas em um modelo genético de cardiomiopatia induzida por hiperatividade simpática; Effect of exercise training on structural cardiac adaptations in a genetic model of cardiomyopathy induced by sympathetic hyperactivity

Oliveira, Rodrigo da Silva Fermino de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 12/03/2009 Português
Relevância na Pesquisa
46.31%
I ntrodução: A insuficiência cardíaca é uma síndrome clínica caracterizada por anormalidades da função do ventrículo esquerdo e regulação neurohormonal, associadas a hipertrofia cardíaca (HC). Dentre as vias intracelulares envolvidas na HC, a via dependente de cálcio calcineurina tem se demonstrado importante. O treinamento físico tem sido utilizado como tratamento coadjuvante de pacientes com IC, mas seu papel sobre a atividade da via da calcineurina relacionado a HC na IC ainda não foi estabelecido. Portanto, neste estudo avaliamos o efeito do treinamento físico sobre a via da calcineurina e sobre a HC em um modelo genético de IC induzida por hiperatividade simpática. Métodos: Estudamos camundongos controle (WT) e com inativação gênica para os receptores adrenérgicos 2A e 2C (2A/2CARKO) dos 5 aos 7 meses, que foram divididos nos grupos WT (n=19), 2A/2CARKO (n=26) e 2A/2CARKO treinados (n=31). O treinamento físico aeróbico em esteira foi realizado durante 8 semanas, 5 vezes por semana por 1 hora. Foi avaliada a tolerância ao esforço pela distância total percorrida em um teste máximo até a exaustão em esteira, a função cardíaca pela fração de encurtamento por meio do ecocardiograma, a estrutura cardíaca pela massa cardíaca das câmaras cardíacas...

Avaliação da musculatura estriada de membros inferiores na limitação funcional ao exercício em pacientes com hipertensão arterial pulmonar; Assessment of skeletal muscle of lower limb in functional exercise limitation in patients with pulmonary arterial hypertension

Breda, Ana Paula
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 25/04/2011 Português
Relevância na Pesquisa
46.32%
Introdução: A hipertensão arterial pulmonar (HAP) é uma doença progressiva extremamente grave, que evolui com insuficiência cardíaca direita e morte. Apesar do avanço do tratamento farmacológico, o prognóstico permanece reservado com taxa de sobrevida de 86%, 70% e 55% em 1, 3 e 5 anos, respectivamente. A dispnéia progressiva e a intolerância ao exercício são as principais manifestações clínicas e refletem a falência do ventrículo direito. O músculo esquelético periférico parece ser também um dos principais determinantes desta limitação funcional, visto que a redução da oferta de oxigênio e alterações na extração/utilização do oxigênio pelo músculo são diretamente relacionados com a tolerância ao exercício. Existem dois mecanismos potencialmente envolvidos na regulação da oferta de oxigênio, e portanto, na capacidade de exercício: mecanismos centrais (função do coração, pulmão e sistema nervoso autônomo) e mecanismos periféricos (associado ao fluxo sanguíneo periférico e a função do músculo esquelético). Os pacientes com HAP geralmente apresentam baixo débito cardíaco e estado adrenérgico exacerbado. A combinação destas alterações pode resultar em alterações estruturais e funcionais da musculatura estriada periférica. Porém...

Comparação das respostas fisiológicas no teste de exercício cardiopulmonar e em três testes de exercício submáximo em pacientes com doença pulmonar obstrutiva crônica; Comparison of physiological responses to the cardiopulmonary exercise test and to three submaximal exercise tests in patients with chronic obstructive pulmonary disease

Pasqualoto, Adriane Schmidt
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Tese de Doutorado Formato: application/pdf
Português
Relevância na Pesquisa
56.47%
INTRODUÇÃO: A doença pulmonar obstrutiva crônica (DPOC) apresenta obstrução crônica ao fluxo aéreo e evolui com perda da capacidade funcional. A intolerância ao exercício é um marcador prognóstico da doença. OBJETIVO: Investigar as respostas fisiológicas no teste incremental com cicloergômetro (TECP), teste do degrau de 6 minutos (TD6), teste da caminhada de 6 minutos (TC6) e teste senta e levanta de um minuto (TSL) em pacientes com DPOC. MÉTODOS: Foram incluídos 24 pacientes com DPOC (VEF1/CVF<70 e VEF1 pós bd <80%), clinicamente estáveis. Todos os pacientes realizaram provas de função pulmonar e os quatro protocolos de exercício. Durante os testes foram medidos: consumo de oxigênio (VO2), produção de CO2 (VCO2), ventilação (VE), frequência cardíaca (FC), frequência respiratória (FR), oximetria de pulso (SpO2), e sensação de dispneia e de desconforto nas pernas (escala de BORG modificada). RESULTADOS: Quinze pacientes eram homens, a média de idade foi de 63,7 ± 6,6 anos e do VEF1 foi de 1,20 ± 0,60 L, 42,5 ± 17,8 % do predito. O VO2pico observado no TD6 (1,01±0,40 L.min-1) não diferiu do VO2 medido no TECP (0,86±0,32 L.min-1) e no TC6 (0,99±0,46; L.min-1;p>0,05). Entretanto, o VO2 pico do TSL foi significativamente inferior (0...

Effect of exercise training and carvedilol treatment on cardiac function and structure in mice with sympathetic hyperactivity-induced heart failure

Medeiro,A.; Vanzelli,A.S.; Rosa,K.T.; Irigoyen,M.C.; Brum,P.C.
Fonte: Associação Brasileira de Divulgação Científica Publicador: Associação Brasileira de Divulgação Científica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2008 Português
Relevância na Pesquisa
46.33%
The present investigation was undertaken to study the effect of β-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 (α2A/α2CArKO). α2A/α2CArKO 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 α2A/α2CArKO mice. At 5 months of age, all α2A/α2CArKO mice displayed exercise intolerance and baseline tachycardia associated with reduced fractional shortening and gastrocnemius capillary rarefaction. In addition...

Noninvasive ventilation and exercise tolerance in heart failure: A systematic review and meta-analysis

Bündchen,Daiana C.; Gonzáles,Ana I.; Noronha,Marcos De; Brüggemann,Ana K.; Sties,Sabrina W.; Carvalho,Tales De
Fonte: Associação Brasileira de Pesquisa e Pós-Graduação em Fisioterapia Publicador: Associação Brasileira de Pesquisa e Pós-Graduação em Fisioterapia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/10/2014 Português
Relevância na Pesquisa
56.45%
Background: Patients with heart failure (HF) usually develop exercise intolerance. In this context, noninvasive ventilation (NIV) can help to increase physical performance. Objective: To undertake a systematic review and meta-analysis of randomized controlled trials that evaluated the effects of NIV on exercise tolerance in patients with HF. Method: Search Strategy: Articles were searched in the following databases: Physiotherapy Evidence Database (PEDro), Scientific Electronic Library Online (SciELO), and MEDLINE. Selection Criteria: This review included only randomized controlled trials involving patients with HF undergoing NIV, with or without other therapies, that used exercise tolerance as an outcome, verified by the distance travelled in the six-minute walk test (6MWT), VO2peak in the cardiopulmonary test, time spent in testing, and dyspnea. Data Collection and Analysis: The methodological quality of the studies was rated according to the PEDro scale. Data were pooled in fixed-effect meta-analysis whenever possible. Results: Four studies were selected. A meta-analysis including 18 participants showed that the use of NIV prior to the 6MWT promoted increased distance, [mean difference 65.29 m (95% CI 38.80 to 91.78)]. Conclusions: The use of NIV prior to the 6MWT in patients with HF may promote increased distance. However...

Exercise intolerance, lactic acidosis, and abnormal cardiopulmonary regulation in exercise associated with adult skeletal muscle cytochrome c oxidase deficiency.

Haller, R G; Lewis, S F; Estabrook, R W; DiMauro, S; Servidei, S; Foster, D W
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /07/1989 Português
Relevância na Pesquisa
46.5%
A 27-yr-old woman with lifelong severe exercise intolerance manifested by muscle fatigue, lactic acidosis, and prominent symptoms of dyspnea and tachycardia induced by trivial exercise was found to have a skeletal muscle respiratory chain defect characterized by low levels of reducible cytochromes a + a3 and b in muscle mitochondria and marked deficiency of cytochrome c oxidase (complex IV) as assessed biochemically and immunologically. Investigation of the pathophysiology of the exercise response in the patient revealed low maximal oxygen uptake (1/3 that of normal sedentary women) in cycle exercise and impaired muscle oxygen extraction as indicated by profoundly low maximal systemic arteriovenous oxygen difference (5.8 ml/dl; controls = 15.4 +/- 1.4, mean +/- SD). The increases in cardiac output and ventilation during exercise, normally closely coupled to muscle metabolic rate, were markedly exaggerated (more than two- to threefold normal) relative to oxygen uptake and carbon dioxide production accounting for prominent tachycardia and dyspnea at low workloads. Symptoms in our patient are similar to those reported in other human skeletal muscle respiratory chain defects involving complexes I and III, and the exaggerated circulatory response resembles that seen during experimental inhibition of the mitochondrial respiratory chain. These results suggest that impaired oxidative phosphorylation in working muscle disrupts the normal regulation of cardiac output and ventilation relative to muscle metabolic rate in exercise.

Chronic Heart Failure and Exercise Intolerance: The Hemodynamic Paradox

Nilsson, Kent R; Duscha, Brian D; Hranitzky, Patrick M; Kraus, William E
Fonte: Bentham Science Publishers Ltd. Publicador: Bentham Science Publishers Ltd.
Tipo: Artigo de Revista Científica
Publicado em /05/2008 Português
Relevância na Pesquisa
46.37%
Heart failure represents a major source of morbidity and mortality in industrialized nations. As the leading hospital discharge diagnosis in the United States in patients over the age of 65, it is also associated with substantial economic costs. While the acute symptoms of volume overload frequently precipitate inpatient admission, it is the symptoms of chronic heart failure, including fatigue, exercise intolerance and exertional dyspnea, that impact quality of life. Over the last two decades, research into the enzymatic, histologic and neurohumoral alterations seen with heart failure have revealed that hemodynamic derangements do not necessarily correlate with symptoms. This “hemodynamic paradox” is explained by alterations in the skeletal musculature that occur in response to hemodynamic derangements. Importantly, gender specific effects appear to modify both disease pathophysiology and response to therapy. The following review will discuss our current understanding of the systemic effects of heart failure before examining how exercise training and cardiac resynchronization therapy may impact disease course.

Fatigue and exercise intolerance in mitochondrial diseases. Literature revision and experience of the Italian Network of mitochondrial diseases

Mancuso, M.; Angelini, C.; Bertini, E.; Carelli, V.; Comi, G.P.; Minetti, C.; Moggio, M.; Mongini, T.; Servidei, S.; Tonin, P.; Toscano, A.; Uziel, G.; Zeviani, M.; Siciliano, G.;
Fonte: Pergamon Press Publicador: Pergamon Press
Tipo: Artigo de Revista Científica
Publicado em 01/12/2012 Português
Relevância na Pesquisa
46.74%
Fatigue and exercise intolerance are common symptoms of mitochondrial diseases, but difficult to be clinically assessed. New methods to quantify these rather common complaints are strongly needed in the clinical practice. Coenzyme Q10 administration and aerobic exercise may improve exercise intolerance, but more definite studies are still pending. Herein, we have revised “how to measure” and “how to treat” these symptoms of mitochondrial patients. Subsequently, we reviewed the clinical data of the 1164 confirmed mitochondrial patients present in the Italian nation-wide database of mitochondrial disease, with special regard to exercise intolerance. We observed that more of 20% of mitochondrial patients complain of exercise intolerance. This symptom seems to be frequently associated with specific patient groups and/or genotypes. Ragged red fibers and COX-negative fibers are more often present in subjects with exercise intolerance, whereas lactate levels could not predict this symptom. Multicenter efforts are strongly needed for rare disorders such as mitochondrial diseases, and may represent the basis for more rigorous longitudinal studies.

Carotid Arterial Stiffness and Its Relationship to Exercise Intolerance in Older Patients with Heart Failure and Preserved Ejection Fraction

Kitzman, Dalane W.; Herrington, David M.; Brubaker, Peter H.; Moore, J. Brian; Eggebeen, Joel; Haykowsky, Mark J.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
46.48%
Heart failure with a preserved ejection fraction (HFpEF) is the dominant form of heart failure in the older population. The primary chronic symptom in HFpEF is severe exercise intolerance, however, its pathophysiology and therapy are not well understood. We tested the hypothesis that older patients with HFpEF have increased arterial stiffness beyond that which occurs with normal aging and that this contributes to their severe exercise intolerance.

Recurrent Syncope Episodes and Exercise Intolerance in Hypertrophic Cardiomyopathy Combined with Atrioventricular Conduction Disturbance

Kim, Kyun Hee; Yang, Dong Heon; Kim, Chang-Yeon; Kim, Nam Kyun; Choi, Won Suk; Bae, Myung Hwan; Lee, Jang Hoon; Park, Hun Sik; Cho, Yongkeun; Chae, Shung Chull
Fonte: Korean Society of Echocardiography Publicador: Korean Society of Echocardiography
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
46.65%
A 30-year-old female patient with known hypertrophic cardiomyopathy (HCMP) was admitted for recurrent syncope episodes. Electrocardiogram (ECG) showed 2 : 1 atrioventricular (AV) block. Stress echocardiography with bicycle showed high grade AV block at high stage of the exercise associated with exercise intolerance and dyspnea. Twenty-four hour ECG monitoring also revealed high grade AV block and 1 episode of non-sustained ventricular tachycardia. Implantable cardioverter/defibrillator-pacemaker (ICD-P) was inserted. After implantation of ICD-P, conduction disturbance and exercise intolerance were improved. AV block is a rare complication HCMP. There are just a few case reports that present symptoms caused by conduction disturbance in HCMP. This case describes repeated syncope episodes and exercise intolerance caused by conduction disturbance during exercise in HCMP patient. For evaluating the cause of syncope in HCMP, stress echocardiography can be helpful to understand the probable mechanism of syncope.

Skeletal muscle abnormalities and exercise intolerance in older patients with heart failure and preserved ejection fraction

Kitzman, Dalane W.; Nicklas, Barbara; Kraus, William E.; Lyles, Mary F.; Eggebeen, Joel; Morgan, Timothy M.; Haykowsky, Mark
Fonte: American Physiological Society Publicador: American Physiological Society
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
46.56%
Heart failure (HF) with preserved ejection fraction (HFPEF) is the most common form of HF in older persons. The primary chronic symptom in HFPEF is severe exercise intolerance, and its pathophysiology is poorly understood. To determine whether skeletal muscle abnormalities contribute to their severely reduced peak exercise O2 consumption (V̇o2), we examined 22 older HFPEF patients (70 ± 7 yr) compared with 43 age-matched healthy control (HC) subjects using needle biopsy of the vastus lateralis muscle and cardiopulmonary exercise testing to assess muscle fiber type distribution and capillarity and peak V̇o2. In HFPEF versus HC patients, peak V̇o2 (14.7 ± 2.1 vs. 22.9 ± 6.6 ml·kg−1·min−1, P < 0.001) and 6-min walk distance (454 ± 72 vs. 573 ± 71 m, P < 0.001) were reduced. In HFPEF versus HC patients, the percentage of type I fibers (39.0 ± 11.4% vs. 53.7 ± 12.4%, P < 0.001), type I-to-type II fiber ratio (0.72 ± 0.39 vs. 1.36 ± 0.85, P = 0.001), and capillary-to-fiber ratio (1.35 ± 0.32 vs. 2.53 ± 1.37, P = 0.006) were reduced, whereas the percentage of type II fibers was greater (61 ± 11.4% vs. 46.3 ± 12.4%, P < 0.001). In univariate analyses, the percentage of type I fibers (r = 0.39, P = 0.003), type I-to-type II fiber ratio (r = 0.33...

Skeletal Muscle Composition and Its Relation to Exercise Intolerance in Older Patients with Heart Failure and Preserved Ejection Fraction

Haykowsky, Mark J.; Kouba, Erik J.; Brubaker, Peter H.; Nicklas, Barbara J.; Eggebeen, Joel; Kitzman, Dalane W.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
46.45%
Exercise intolerance is the primary chronic symptom in heart failure with preserved ejection fraction (HFpEF), the most common form of HF in older patients, however its pathophysiology is not well understood. Recent data suggest that peripheral factors, such as skeletal muscle dysfunction, may be important contributors. Therefore, 38 participants, 23 HFpEF patients (69±7 years) and 15 age-matched healthy controls (HC), underwent magnetic resonance imaging and cardiopulmonary exercise testing to assess for: skeletal muscle (SM), intermuscular fat (IMF), subcutaneous fat (SCF), total thigh, and thigh compartment areas (TC) and peak exercise oxygen consumption (peak VO2). There were no significant inter-group differences in total thigh area, TC, SCF, or SM. However, in HFpEF versus HC, IMF area (35.6±11.5 vs. 22.3±7.6 cm2, p=0.01), percent IMF/TC (26±5 vs. 20±5%, p=0.005), and the ratio of IMF/SM (0.38±0.10 vs. 0.28±0.09, p=0.007) were significantly increased, while percent SM/TC was significantly reduced (70±5 vs. 75 ±5, p=0.009). In multivariate analyses, IMF area (partial r= -0.51, p=0.002) and IMF/SM ratio (partial r= -0.45, p=0.006) were independent predictors of peak VO2 while SM area was not (partial r=-0.14, p=0.43). Thus...

Genetic Ablation of CD38 Protects against Western Diet-Induced Exercise Intolerance and Metabolic Inflexibility

Chiang, Shian-Huey; Harrington, W. Wallace; Luo, Guizhen; Milliken, Naphtali O.; Ulrich, John C.; Chen, Jing; Rajpal, Deepak K.; Qian, Ying; Carpenter, Tiffany; Murray, Rusty; Geske, Robert S.; Stimpson, Stephen A.; Kramer, Henning F.; Haffner, Curt D.; B
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 19/08/2015 Português
Relevância na Pesquisa
46.37%
Nicotinamide adenine dinucleotide (NAD+) is a key cofactor required for essential metabolic oxidation-reduction reactions. It also regulates various cellular activities, including gene expression, signaling, DNA repair and calcium homeostasis. Intracellular NAD+ levels are tightly regulated and often respond rapidly to nutritional and environmental changes. Numerous studies indicate that elevating NAD+ may be therapeutically beneficial in the context of numerous diseases. However, the role of NAD+ on skeletal muscle exercise performance is poorly understood. CD38, a multi-functional membrane receptor and enzyme, consumes NAD+ to generate products such as cyclic-ADP-ribose. CD38 knockout mice show elevated tissue and blood NAD+ level. Chronic feeding of high-fat, high-sucrose diet to wild type mice leads to exercise intolerance and reduced metabolic flexibility. Loss of CD38 by genetic mutation protects mice from diet-induced metabolic deficit. These animal model results suggest that elevation of tissue NAD+ through genetic ablation of CD38 can profoundly alter energy homeostasis in animals that are maintained on a calorically-excessive Western diet.

Tai chi mind-body exercise in patients with COPD: study protocol for a randomized controlled trial

Yeh, Gloria Y; Wayne, Peter M; Litrownik, Daniel; Roberts, David H; Davis, Roger B; Moy, Marilyn L
Fonte: BioMed Central Publicador: BioMed Central
Tipo: Artigo de Revista Científica
Português
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46.32%
Background: Chronic obstructive pulmonary disease (COPD) is a chronic, progressively debilitating condition that is prevalent in the US and worldwide. Patients suffer from progressive dyspnea and exercise intolerance. Physical exercise is beneficial, but conventional pulmonary rehabilitation programs are underutilized. There remains a need for novel interventions that improve symptoms, quality-of-life, and functional capacity. Tai chi is an increasingly popular mind-body exercise that includes physical exercise, breathing training, mindful awareness, and stress management--components that are essential to the self-management of COPD. There are, however, limited data on the effectiveness of tai chi as a therapeutic intervention in this population. Methods/Design The Primary Aims are to evaluate the efficacy, safety, and feasibility of a 12-week tai chi program for patients with COPD. We utilize a randomized controlled trial design, with participants assigned in a 2:1 ratio to either a group tai chi program (N = 63) or a time/attention-matched education control (N = 31). Our primary outcomes are COPD-specific quality-of-life and exercise capacity. Secondary outcomes include dyspnea, mood, functional status, self-efficacy, and lung function. Cardiopulmonary exercise testing is done in a subset of patients (N = 50). To explore optimal training duration...

Influence of Caffeine on Exercising Muscle Blood Flow and Exercise Tolerance in Type II Diabetes

POITRAS, VERONICA
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado Formato: 3530486 bytes; application/pdf
Português
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BACKGROUND: Exercise is a critical treatment modality in persons with Type II Diabetes Mellitus (T2DM), however people with this disease experience chronic fatigue and a decreased exercise capacity, which affects their ability or willingness to participate in physical activity. Studies suggest that this exercise intolerance may be partly due to a reduced exercising muscle blood flow (MBF), and in particular to a reduced ability of red blood cells (RBCs) to evoke ATP-mediated vasodilation and an increase in MBF as they traverse areas of high O2 demand. Additional evidence suggests that caffeine may attenuate this impairment by enhancing the release of ATP from RBCs. HYPOTHESIS: Persons with T2DM would have reduced Forearm Blood Flow (FBF), oxygen consumption (VO2), and exercise tolerance responses to exercise compared to control (CON) subjects, and caffeine would attenuate these impairments. METHODS: T2DM (n = 4) and CON (n = 4) participants performed rhythmic forearm handgrip exercise at an intensity equivalent to 17.5 kg until “task failure” or 20 minutes of exercise was reached, after having consumed either a caffeine (5mg/kg; Caff) or placebo (Pl) capsule. FBF (Doppler and Echo ultrasound of the brachial artery), VO2 and lactate efflux (deep venous blood sampling)...