RESUMO Introdução A prática regular de exercícios físicos ou o estilo de vida mais ativo são importantes na prevenção de doenças cardiovasculares, reduzindo não somente a mortalidade cardiovascular, mas também favorecendo a redução dos fatores de risco relacionados com essas doenças. Objetivo Avaliar a associação entre inatividade física e variabilidade da frequência cardíaca (VFC) em adolescentes. Métodos Este foi um estudo transversal do tipo Diagnóstico com Nível de Evidência II segundo a tabela de Oxford. Foram avaliados 129 adolescentes com idades entre 15 e 17 anos, divididos em quatro grupos: adolescentes insuficientemente ativos (IAM, n = 28) ou fisicamente ativos (FAM, n = 29) do sexo masculino e adolescentes, insuficientemente ativos (IAF, n = 42) ou fisicamente ativos do sexo feminino (FAF, n = 30). O nível de atividade física foi avaliado por meio do IPAQ. A VFC foi avaliada no domínio do tempo e da frequência. Resultados Nos adolescentes do sexo masculino e feminino, foram observados valores menores na variância do intervalo de pulso nos grupos insuficientemente ativos (5.089 ± 378 ms2 e 4.335 ± 276 ms2, respectivamente) quando comparados com os grupos fisicamente ativos (9.106 ± 606 ms2 e 6.182 ± 366 ms2, respectivamente). Além disso, os grupos insuficientemente ativos apresentaram maiores valores de balanço simpato-vagal cardíaco (0,81 ± 0,05 e 0,80 ± 0,05, respectivamente) comparados aos dos grupos fisicamente ativos (0,63 ± 0,05 e 0,55 ± 0,05, respectivamente). Conclusão A vida fisicamente ativa foi associada à melhor modulação cardiovascular autonômica em adolescentes. Nível de Evidência II; Estudos diagnósticos – Investigação de um exame para diagnóstico.

ABSTRACT Introduction Regular physical exercise, or a more active lifestyle, are important to prevent cardiovascular diseases, reducing not only cardiovascular mortality but also promoting a reduction in the risk factors related to these diseases. Objective To assess the association between physical inactivity and heart rate variability (HRV) in adolescents. Methods This was a cross-sectional study of the Diagnostic Type with Level of Evidence II according to the Oxford table. One hundred and twenty-nine adolescents were evaluated, aged 15 and 17 years old, divided into four groups: male teenagers who were insufficiently active (IAM n = 28) or physically active (FAM n = 29), and female teenagers who were insufficiently active (IAF n = 42) or physically active (FAF n = 30). The level of physical activity was assessed by the IPAQ. The HRV was evaluated in the time and frequency domains. Results Reduced pulse interval variance was observed in the insufficiently active male or female groups (5089 ± 378 ms2 and 4335 ± 276 ms2 respectively) compared to the physically active groups (9106 ± 606 ms2 and 6182 ± 366 ms2 respectively). Moreover, the insufficiently active groups presented higher cardiac sympathetic/vagal balance values (0.81 ± 0.05 and 0.80 ± 0.05 respectively) compared to the physically active groups (0.63 ± 0.05 and 0.55 ± 0.05 respectively). Conclusion A physically active lifestyle was associated with better cardiovascular autonomic modulation in adolescents. Level of Evidence II; Diagnostic Studies - Investigating a Diagnostic Test.

RESUMEN Introducción La práctica regular de ejercicios físicos o el estilo de vida más activo son importantes en la prevención de enfermedades cardiovasculares, reduciendo no sólo la mortalidad cardiovascular, sino también favoreciendo la reducción de los factores de riesgo relacionados con esas enfermedades. Objetivo Evaluar la asociación entre inactividad física y variabilidad de la frecuencia cardíaca (VFC) en adolescentes. Métodos Este fue un estudio transversal del tipo Diagnóstico con Nivel de Evidencia II según la tabla de Oxford. Se evaluaron 129 adolescentes con edades entre 15 y 17 años, divididos en cuatro grupos: adolescentes insuficientemente activos (IAM, n=28) o físicamente activos (FAM, n=29) del sexo masculino y adolescentes insuficientemente activos (IAF, n=42) o físicamente activos del sexo femenino (FAF, n=30). El nivel de actividad física fue evaluado a través del IPAQ. La VFC fue evaluada en el dominio del tiempo y de la frecuencia. Resultados Los adolescentes del sexo masculino y femenino insuficientemente activos presentaron valores menores en la varianza del intervalo de pulso (5.089 ± 378; y 4.335 ± 276 ms2, respectivamente) cuando se compararon con los grupos físicamente activos (9.106 ± 606 y 6.182 ± 366 ms2, respectivamente). Además, los grupos insuficientemente activos presentaron mayores valores del balance simpático-vagal cardíaco (0,81 ± 0,05 y 0,80 ± 0,05, respectivamente) comparados a los grupos físicamente activos (0,63 ± 0,05 y 0,55 ± 0,05, respectivamente). Conclusión La vida físicamente activa fue asociada a la mejor modulación cardiovascular autonómica en adolescentes. Nivel de Evidencia II; Estudios de diagnósticos - Investigación de un examen para diagnóstico.

A hipertensão arterial sistêmica é considerada o maior fator de risco para o desenvolvimento de patologias neuro-cardiovasculares, constituindo um grave problema de Saúde Pública no mundo. O laser de baixa intensidade, ou laserterapia, ativa componentes da estrutura celular, convertendo energia luminosa em energia fotoquímica, e levando a reações biofísicas e bioquímicas na cadeia respiratória mitocondrial. O laser de baixa intensidade promove a fotobiomodulação celular/tissular, por meio de modificações no metabolismo, incorrendo em alterações moleculares, celulares e sistêmicas. O objetivo deste estudo foi analisar a ação do laser de baixa intensidade na modulação hemodinâmica em ratos espontaneamente hipertensos, em longo prazo. Os animais (n = 16) foram divididos aleatoriamente em Grupo Laser (n = 8), que recebeu três irradiações semanais do laser de baixa intensidade durante 7 semanas, e em Grupo Sham (n = 8), que recebeu três simulações semanais de laser durante 7 semanas, totalizando 21 aplicações em cada grupos. Após 7 semanas, os animais foram canulados com implantação do cateter na artéria carótida esquerda. No dia subsequente, foram realizados registros da pressão arterial sistêmica. O Grupo Laser evidenciou, com diferenças estatisticamente significantes, redução nos níveis da pressão arterial média (169 ± 4 mmHg* vs. 182 ± 4 mmHg do Grupo Sham) e da pressão arterial diastólica (143 ± 4 mmHg* vs. 157 ± 3 mmHg do Grupo Sham), revelando diminuição de 13 e 14 mmHg, respectivamente. Ademais, ocorreu concomitante um importante decréscimo da frequência cardíaca (312 ± 14 bpm vs. 361 ± 13 bpm do Grupo Sham). Dessa forma, a laserterapia foi capaz de produzir alterações hemodinâmicas, reduzindo os níveis pressóricos em ratos espontaneamente hipertensos.

Systemic arterial hypertension (SAH) is considered to be the greatest risk factor for the development of neuro-cardiovascular pathologies, thus constituting a severe Public Health issue in the world. The Low-Level Laser Therapy (LLLT), or laser therapy, activates components of the cellular structure, therefore converting luminous energy into photochemical energy and leading to biophysical and biochemical reactions in the mitochondrial respiratory chain. The LLLT promotes cellular and tissue photobiomodulation by means of changes in metabolism, leading to molecular, cellular and systemic changes. The objective of this study was to analyze the action of low-level laser in the hemodynamic modulation of spontaneously hypertensive rats, in the long term. Animals (n = 16) were randomly divided into the Laser Group (n = 8), which received three weekly LLLT irradiations for seven weeks, and into the Sham Group (n = 8), which received three weekly simulations of laser for seven weeks, accounting for 21 applications in each group. After seven weeks, animals were cannulated by the implantation of a catheter in the left carotid artery. On the following day, the systemic arterial pressure was recorded. The Laser Group showed reduced levels of mean blood pressure, with statistically significant reduction (169 ± 4 mmHg* vs. 182 ± 4 mmHg from the Sham Group) and reduced levels of diastolic pressure (143 ± 4 mmHg* vs. 157 ± 3 mmHg from the Sham Group), revealing a 13 and 14 mmHg decrease, respectively. Besides, there was a concomitant important decline in heart rate (312 ± 14 bpm vs. 361 ± 13 bpm from the Sham Group). Therefore, laser therapy was able to produce hemodynamic changes, thus reducing pressure levels in spontaneously hypertensive rats.

OBJECTIVES: Aerobic exercise training prevents cardiovascular risks. Regular exercise promotes functional and structural adaptations that are associated with several cardiovascular benefits. The aim of this study is to investigate the effects of swimming training on coronary blood flow, adenosine production and cardiac capillaries in normotensive rats. METHODS: Wistar rats were randomly divided into two groups: control (C) and trained (T). An exercise protocol was performed for 10 weeks and 60 min/day with a tail overload of 5% bodyweight. Coronary blood flow was quantified with a color microsphere technique, and cardiac capillaries were quantified using light microscopy. Adenine nucleotide hydrolysis was evaluated by enzymatic activity, and protein expression was evaluated by western blot. The results are presented as the means ± SEMs (p<0.05). RESULTS: Exercise training increased the coronary blood flow and the myocardial capillary-to-fiber ratio. Moreover, the circulating and cardiac extracellular adenine nucleotide hydrolysis was higher in the trained rats than in the sedentary rats due to the increased activity and protein expression of enzymes, such as E-NTPDase and 59- nucleotidase. CONCLUSIONS: Swimming training increases coronary blood flow, number of cardiac capillaries, and adenine nucleotide hydrolysis. Increased adenosine production may be an important contributor to the enhanced coronary blood flow and angiogenesis that were observed in the exercise-trained rats; collectively, these results suggest improved myocardial perfusion.

OBJECTIVES: We investigated the effects of treadmill training (10 weeks) on hindlimb motor function and nerve morphometric parameters in diabetic rats submitted to sciatic nerve crush. MATERIALS AND METHOD: Wistar rats (n = 64) were divided into the following groups: non-diabetic; trained non-diabetic; non-diabetic with sciatic nerve crush; trained non-diabetic with sciatic nerve crush; diabetic; trained diabetic; diabetic with sciatic nerve crush or trained diabetic with sciatic nerve crush. Diabetes was induced by streptozotocin injection (50 mg/kg, iv). Hindlimb motor function was evaluated weekly by assessing sciatic functional indices, and the proximal and distal portions of the sciatic nerve were used for morphometric analysis. RESULTS: At 13 weeks post-injury, the distal nerve portion of all injured groups and the proximal nerve portion of the diabetic with sciatic nerve crush group presented altered morphometric parameters such as decreased myelinated fiber diameter (~7.4 + 0.3μm vs ~4.8 + 0.2μm), axonal diameter (~5 + 0.2μm vs ~3.5 + 0.1μm) and myelin sheath thickness (~1.2 + 0.07μm vs ~0.65 + 0.07μm) and an increase in the percentage of area occupied by endoneurium (~28 + 3% vs ~60 + 3%). In addition, in the non-diabetic with sciatic nerve crush group the proximal nerve portion showed a decreased myelinated fiber diameter (7.4+0.3μm vs 5.8 + 0.3μm) and myelin sheath thickness (1.29 + 0.08μm vs 0.92 + 0.08μm). The non-diabetic with sciatic nerve crush, trained non-diabetic with sciatic nerve crush, diabetic with sciatic nerve crush and trained diabetic with sciatic nerve crush groups showed normal sciatic functional index from the 4th,4th,9th and 7th week post-injury, respectively. Morphometric alterations in the proximal nerve portion of the diabetic with sciatic nerve crush and non-diabetic with sciatic nerve crush groups were either prevented or reverted to values similar to the non-diabetic group by treadmill training. CONCLUSION: Diabetic condition promoted delay in sciatic nerve regeneration. Treadmill training is able to accelerate hindlimb motor function recovery in diabetic injured rats and prevent or revert morphometric alterations in proximal nerve portions in non-diabetic and diabetic injured rats.

Um aumento no risco de tromboembolismo venoso têm sido descrito em usuárias de anticoncepcionais hormonais oral de terceira geração. OBJETIVO: Avaliar o efeito de um anticoncepcional combinado hormonal oral de baixa dose (15 µg etinil estradiol/60 µg gestodeno) na função endotelial venosa de mulheres jovens saudáveis. MÉTODOS: Realizou-se um estudo caso-controle prospectivo em vinte mulheres jovens saudáveis que foram avaliadas pela técnica da complascência venosa. A função endotelial venosa foi avaliada em um momento basal e após 4 meses no grupo das usuárias de anticoncepcional oral (11 mulheres) e em um grupo controle (9 mulheres). Foram construídas curvas dose resposta para acetilcolina e nitroprussiato de sódio após a pré-constrição da veia com fenilefrina. RESULTADOS: No grupo de usuárias de anticoncepcional combinado hormonal oral houve diminuição da venodilatação máxima em resposta a acetilcolina e nitroprussiato de sódio, porém esta mudança não foi estatisticamente significante (p> 0,05). No grupo controle não foram detectadas mudanças significantes na venodilatação máxima, em resposta a acetilcolina e nitroprussiato de sódio no intervalo de 4 meses. CONCLUSÃO: Este estudo não observou redução significante da venodilatação endotélio dependente e independente após os uso de anticoncepcional combinado hormonal oral. Mais estudos são necessários utilizando a mesma metodologia em uma amostra maior e com maior tempo de seguimento.

BACKGROUND: A possible increase in the incidence of venous thromboembolic events has been reported among users of third generation oral contraceptives. The objective of this study was to evaluate the effect of a low dose oral contraceptive (15 µg ethinyl estradiol/60 µg gestodene) on the venous endothelial function of healthy young women. METHODS: Prospective case control study using the dorsal hand vein technique. Venous endothelial function was evaluated at baseline and after 4 months in the oral contraceptive users group (11 women) and in a control group (9 women). After preconstriction of the vein with phenylephrine, dose-response curves for acetylcholine and sodium nitroprusside were constructed. RESULTS: In the contraceptive users group, a reduction occurred in the maximum venodilation response to acetylcholine and sodium nitroprusside after 4 months of oral contraceptive use, but this difference was not statistically significant (P > 0.05). No significant changes were detected in maximum venodilation responses to acetylcholine and sodium nitroprusside at the 4-month time point in the control group. CONCLUSION: This study found no significant impairment of endothelium-dependent or independent venodilation in healthy young women following oral contraceptive use. Further studies are necessary using the same methodology in a larger sample over a longer follow-up period.