Influence of Taurine on Cardiac Remodeling Induced by Tobacco Smoke Exposure

Background/Aims: To investigate the effect of taurine on cardiac remodeling induced by smoking. Methods: In the first step, rats were allocated into two groups: Group C (n=14): control; Group T (n=14): treated with taurine (3% in drinking water), for three months. In the second step, rats were allocated into two groups: Group ETS (n=9): rats exposed to tobacco smoke; Group ETS-T (n=9): rats exposed to tobacco smoke and treated with taurine for two months. Results: After three months, taurine presented no effects on morphological or functional variables of normal rats assessed by echocardiogram. on the other hand, after two months, ETS-T group presented higher LV wall thickness (ETS=1.30 (1.20-1.42); ETS-T=1.50 (1.40-1.50); p=0.029), E/A ratio (ETS=1.13 +/- 0.13; ETS-T=1.37 +/- 0.26; p=0.028), and isovolumetric relaxation time normalized for heart rate (ETS=53.9 +/- 4.33; ETS-T=72.5 +/- 12.0; p<0.001). The cardiac activity of the lactate dehydrogenase was higher in the ETS-T group (ETS=204 +/- 14 nmol/mg protein; ETS-T=232 +/- 12 nmol/mg protein; p<0.001). ETS-T group presented lower levels of phospholamban (ETS=1.00 +/- 0.13; ETS-T=0.82 +/- 0.06; p=0.026), phosphorylated phospholamban at Ser16 (ETS=1.00 +/- 0.14;ETS-T=0.63 +/- 0.10;p=0.003), and phosphorylated phosfolamban/phospholamban ratio (ETS=1.01 +/- 0.17; ETS-T=0.77 +/- 0.11; p=0.050). Conclusion: In normal rats, taurine produces no effects on cardiac morphological or functional variables. on the other hand, in rats exposed to cigarette smoke, taurine supplementation increases wall thickness and worsens diastolic function, associated with alterations in calcium handling protein and cardiac energy metabolism. Copyright (C) 2011 S. Karger AG, Basel

Tissue Vitamin A Insufficiency Results in Adverse Ventricular Remodeling after Experimental Myocardial Infarction

Background/Aims: The role of tissue vitamin-A insufficiency on post-infarction ventricular remodeling is unknown. We tested the hypothesis that cardiac vitamin A insufficiency on post-infarction is associated with adverse myocardial remodeling. Methods: After infarction, rats were allocated into two groups: C (controls, n=25); VA (dietary vitamin A restriction, n= 26). After 3 months, the animals were submitted to echocardiogram, morphometric and biochemical analysis. Results: Rats fed the vitamin-A-deficient diet had lower heart and liver retinol concentration and normal plasma retinol. There were no differences in infarct size between the groups. VA showed higher diastolic left ventricular area normalised by body weight (C= 1.81 +/- 0.4 cm2/kg, VA= 2.15 +/- 0.3 cm2/kg; p=0.03), left ventricular diameter (C= 9.4 +/- 1.4 mm, VA= 10.5 +/- 1.2 mm; p=0.04), but similar systolic ventricular fractional area change (C= 33.0 +/- 10.0 %, VA= 32.1 +/- 8.7 %; p=0.82). VA showed decreased isovolumetric relaxation time normalised by heart rate (C= 68.8 +/- 11.4 ms, VA= 56.3 +/- 16.8 ms; p=0.04). VA showed higher interstitial collagen fraction (C= 2.8 +/- 0.9 %, VA= 3.7 +/- 1.1 %; p=0.05). There were no differences in myosin heavy chain expression, metalloproteinase 2 and 9 activation, or IFN-gamma and TNF-alpha cardiac levels. Conclusion: Local tissue vitamin A insufficiency intensified ventricular remodeling after MI, worsening diastolic dysfunction. Copyright (C) 2010 S. Karger AG, Basel

Aldosterone is not Involved in the Ventricular Remodeling Process Induced by Tobacco Smoke Exposure

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Negative chronotropic response to adenosine receptor stimulation in rat right atria after run training

The aim of the present study was to evaluate the potency and maximal responses (E-max) to the adenosine receptor agonists N-6-cyclopentyladenosine (CPA), N-ethylcarboxamidoadenosine (NECA) and N-6-(3-iodobenzyl)-5'-N-methylcarbaxamidoadenosine (IB-MECA) in right atria from trained rats. We also investigated the interaction between the training bradycardia and the sensitivity of the chronotropic response mediated by adenosine receptor stimulation.2. Animals were submitted to run training for 60 min, 5 days a week, over a period of 8 weeks. Mean blood pressure and heart rate were measured in conscious animals. Right atria were isolated and concentration-response curves to CPA, NECA and IB-MECA were obtained.3. A reduction in heart rate was found in trained rats, indicating that the training programme was successful in inducing physical conditioning. The three adenosine receptor agonists induced a concentration-dependent negative chronotropic response. The rank order of potency and E-max for the three adenosine receptor agonists was CPA>NECA>IB-MECA.4. Dynamic exercise for 8 weeks did not alter the E a, for CPA, NECA and IB-MECA. Similarly, the potencies of CPA and NECA were not affected by run training, whereas the potency of IB-MECA was reduced (6.10+/-0.09 vs 5.66+/-0.10 for sedentary and trained groups, respectively).5. In conclusion, run training for 8 weeks induced a desensitization of the chronotropic response to IB-MECA without changing the potency of CPA and NECA. These findings exclude the participation of adenosine receptors in the training bradycardia.

Effects of exercise training on the cardiovascular system: Pharmacological approaches

Physical exercise promotes beneficial health effects by preventing or reducing the deleterious effects of pathological conditions, such as arterial hypertension, coronary artery disease, atherosclerosis, diabetes mellitus, osteoporosis, Parkinson's disease, and Alzheimer disease. Human movement studies are becoming an emerging science in the epidemiological area and public health. A great number of studies have shown that exercise training, in general, reduces sympathetic activity and/or increases parasympathetic tonus either in human or laboratory animals. Alterations in autonomic nervous system have been correlated with reduction in heart rate (resting bradycardia) and blood pressure, either in normotensive or hypertensive subjects. However, the underlying mechanisms by which physical exercise produce bradycardia and reduces blood pressure has not been fully understood. Pharmacological studies have particularly contributed to the comprehension of the role of receptor and transduction signaling pathways on the heart and blood vessels in response to exercise training. This review summarizes and examines the data from studies using animal models and human to determine the effect of exercise training on the cardiovascular system. (c) 2007 Elsevier B.V. All rights reserved.

Validade das equações preditivas da frequência cardíaca máxima para crianças e adolescentes

FUNDAMENTO: Ausência de estudos na literatura validando equações preditivas da frequência cardíaca máxima (FCmáx) em crianças e adolescentes. OBJETIVO: Analisar a validade das equações preditivas da FCmáx 220 - idade e 208 - (0,7 x idade) em meninos com idades entre 10 e 16 anos. MÉTODOS: Um teste progressivo de esforço máximo foi realizado em 69 meninos com idades entre 10 e 16 anos, aparentemente saudáveis e ativos. A velocidade inicial do teste foi de 9 km/h com incrementos de 1 km/h a cada três minutos. O teste foi mantido até a exaustão voluntária, considerando-se como FCmáx a maior frequência cardíaca atingida durante o teste. A FCmáx medida foi comparada com os valores preditos pelas equações 220 - idade e 208 - (0,7 x idade) através da ANOVA, medidas repetidas. Resultados: Os valores médios da FCmáx (bpm) foram: 200,2 ± 8,0 (medida), 207,4 ± 1,5 (220 - idade) e 199,2 ± 1,1 (208 - (0,7 x idade)). A FCmáx predita pela equação 220 - idade foi significantemente maior (p < 0,001) que a FCmáx medida e que a FCmáx predita pela equação (208 - (0,7 x idade)). A correlação entre a FCmáx medida e a idade não foi estatisticamente significativa (r = 0,096; p > 0,05). CONCLUSÃO: A equação 220 - idade superestimou a FCmáx medida e não se mostrou válida para essa população. A equação 208 - (0,7 x idade) se mostrou válida apresentando resultados bastante próximos da FCmáx medida. Estudos futuros estudos com amostras maiores poderão comprovar se a FCmáx não depende da idade para essa população, situação em que o valor constante de 200 bpm seria mais apropriado para a FCmáx.

Efeitos do estado e especificidade do treinamento aeróbio na relação %VO2max versus %FCmax durante o ciclismo

OBJETIVO: Determinar os efeitos do estado e especificidade de treinamento aeróbio na relação entre o percentual do consumo máximo de oxigênio (%VO2max) e o percentual da frequência cardíaca máxima (%FCmax) durante o exercício incremental realizado no cicloergômetro. MÉTODOS: Sete corredores, 9 ciclistas, 11 triatletas e 12 sedentários, todos do sexo masculino e aparentemente saudáveis, foram submetidos a um teste incremental até a exaustão no cicloergômetro. Regressões lineares entre %VO2max e %FCmax foram determinadas para cada indivíduo. Com base nessas regressões, foram calculados %FCmax correspondentes a determinados %VO2max (50, 60, 70, 80 e 90%) de cada participante. RESULTADOS: Não foram encontradas diferenças significantes entre todos os grupos nos %FCmax para cada um dos %VO2max avaliados. Analisando-se os voluntários como um único grupo, as médias dos %FCmax correspondentes a 50, 60, 70, 80 e 90% %VO2max foram 67, 73, 80, 87, e 93%, respectivamente. CONCLUSÃO: Nos grupos analisados, a relação entre o %VO2max e %FCmax durante o exercício incremental no ciclismo não é dependente do estado e especificidade do treinamento aeróbio.

Respostas do lactato sanguíneo e da freqüência cardíaca em duas diferentes provas do automobilismo

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Adaptação da máscara do analisador de gases VO2000 para mensuração de parâmetros cardiorrespiratórios em natação

O objetivo do presente estudo foi desenvolver um snorquel (SNQ) de baixo custo para mensuração de parâmetros cardiorrespiratórios em natação. Para isso, a máscara do analisador de gases VO2000 (MASC) foi adaptada a um SNQ desenvolvido artesanalmente com espaço morto de 250ml. Oito participantes foram submetidos a dois testes incrementais (TI) em cicloergômetro utilizando a MASC e o SNQ. Os TI foram realizados até a exaustão voluntária e foram compostos por estágios de 3min com carga inicial e incrementos de 35W. em ambas as situações, amostras gasosas foram coletadas em intervalos de 10s para determinação dos volumes de oxigênio (VO2), gás carbônico (VCO2), ventilatório (VE) e mensuração da freqüência cardíaca (FC). A comparação dos parâmetros cardiorrespiratórios (VO2, VE, VCO2 e FC) mensurados com o SNQ e a MASC foi realizada com o teste t de Student para amostras dependentes, enquanto que o teste de correlação de Pearson e a análise gráfica de Bland e Altman foram utilizados para verificar as associações e concordância entre parâmetros. em todos os casos, o nível de significância foi de P < 0,05. A adequação das equações de correção para os valores provenientes do SNQ foi verificada pelos erros sistemáticos (bias), aleatórios (precisão) e acurácia (ac). Não foram observadas diferenças significativas entre os valores de VO2, VCO2 e FC obtidos com a MASC e SNQ. Os valores de VE mensurados com o SNQ foram significativamente superiores aos obtidos com a MASC. No entanto, todos os parâmetros apresentaram elevada concordância e coeficiente de correlação (0,88 a 0,97). Além disso, foram verificados reduzidos valores de bias (VO2 = 0,11L/min; VE = 4,11L/min; VCO2 = 0,54L/min; 8,87bpm), precisão (VO2 = 0,24L/min; VE = 11,02L/ min; VCO2 = 0,18L/min; 7,42bpm) e ac (VO2 = 0,27L/min; VE = 11,76L/min; VCO2 = 0,56L/min; 11,56bpm). Desse modo, pode-se concluir que o SNQ desenvolvido neste estudo possibilita a mensuração válida de parâmetros cardiorrespiratórios em natação.

Serum electrolyte and total protein alterations in Pantaneiro horse during long distance exercise

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

PHYSIOLOGICAL and NEUROMUSCULAR PROFILE DURING A BODYPUMP SESSION: ACUTE RESPONSES DURING A HIGH-RESISTANCE TRAINING SESSION

Oliveira, AS, Greco, CC, Pereira, MP, Figueira, TR, de Araujo Ruas, VD, Goncalves, M, and Denadai, BS. Physiological and neuromuscular profile during a Bodypump session: acute responses during a high-resistance training session. J Strength Cond Res 23(2): 579-586, 2009-The main purposes of this study were 1) to describe and to compare blood lactate ([La]), heart rate (HR), and electromyographic (EMG) parameters during high-repetition training sessions (HRTSs), 2) to analyze the influence of physical fitness levels in these parameters, and, 3) to analyze the relationship between metabolic ([La]) and neuromuscular (EMG) responses during the HRTS. Fifteen healthy untrained women (21.7 +/- 2.1 years) performed an HRTS called Bodypump for 1 hour, which incorporated the use of variable free weights and high repetitions in a group setting. This session involved 10 music selections (M1-M10) containing resistive exercises for different muscle groups. After music selections 2 (M2), 4 (M4), 6 (M6), 7 (M7), and 9 (M9), [La], HR, and EMG (vastus medialis [VM], vastus lateralis [VL], iliocostalis lumborum [IC], and longissimus thoracis <) were determined. The [La] (M2, 4.00 +/- 1.45 mM; M7, 5.02 +/- 1.73 mM) and HR (M2, 153.64 +/- 18.89 bpm; M7, 16.14 +/- 20.14 bpm) obtained at M2 and M7 were similar but were significantly higher than the other moments of the session. However, EMG (root mean square [RMS]) at M2 (VL, VM, and LT) was lower than at M7. There was no significant correlation of strength and aerobic physical fitness with [La], RMS. In the same way, there was no significant correlation of [La] with RMS at M2 and M7. on the basis of our data, we can conclude that metabolic, cardiovascular, and EMG variables present different and independent behavior during an HRTS. Accordingly, for neuromuscular conditions during HRTS, it seems to be enough to induce improvement in the muscular strength of inferior limbs in untrained subjects.

PHYSIOLOGICAL and PERCEIVED EXERTION RESPONSES AT INTERMITTENT CRITICAL POWER and INTERMITTENT MAXIMAL LACTATE STEADY STATE

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

THE INFLUENCE of RESTING PERIOD LENGTH on JUMPING PERFORMANCE

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

PRODUCTION of FREE RADICALS and CATALASE ACTIVITY DURING ACUTE EXERCISE TRAINING IN YOUNG MEN

Reactive oxygen species (ROS) are constantly produced by cells that promote cellular oxidative damage and are neutralized by an antioxidant system including superoxide dismutase, glutathione, peroxidase and catalase. Male volunteers were exercised for 20 minutes, three days (60, 70 and 80% of maximum heart rate). Catalase activity and plasma malondialdehyde concentration were measured. The mean age of the volunteers was 25 +/- 7 years, with body mass index 2 of 24.03 +/- 4.32 kg/m(2). Acute exercise training produced an increase of malondialdehyde concentration that was exercise intensity-dependent in young volunteers. However, catalase activity shows a great variability at baseline and the percentual of reduction was exercise intensity-independent in this particular population. Therefore, our study shows that acute cycling exercise promotes an increase of oxidative stress that was exercise intensity-dependent in young volunteers. Furthermore, the antioxidant system measured by catalase activity was effective to counterbalance the ROS production showing a saturation behavior at an intensity of 70% of maximum heart rate.

The rating of perceived exertion predicts intermittent vertical jump demand and performance

The aims of this study were (a) to assess the ability of the rating of perceived exertion (RPE) to predict performance (i.e. number of vertical jumps performed to a fixed jump height) of an intermittent vertical jump exercise, and (b) to determine the ability of RPE to describe the physiological demand of such exercise. Eight healthy men performed intermittent vertical jumps with rest periods of 4, 5, and 6s until fatigue. Heart rate and RPE were recorded every five jumps throughout the sessions. The number of vertical jumps performed was also recorded. Random coefficient growth curve analysis identified relationships between the number of vertical jumps and both RPE and heart rate for which there were similar slopes. In addition, there were no differences between individual slopes and the mean slope for either RPE or heart rate. Moreover, RPE and number of jumps were highly correlated throughout all sessions (r=0.97-0.99; P0.001), as were RPE and heart rate (r=0.93-0.97; P0.001). The findings suggest that RPE can both predict the performance of intermittent vertical jump exercise and describe the physiological demands of such exercise.