BackgroundPeripheral skeletal muscle is altered in patients suffering from emphysema and chronic obstructive pulmonary disease (COPD). Oxidative stress have been demonstrated to participate on skeletal muscle loss of several states, including disuse atrophy, mechanical ventilation, and chronic diseases. No evidences have demonstrated the occurance in a severity manner.MethodsWe evaluated body weight, muscle loss, oxidative stress, and chymotrypsin-like proteolytic activity in the gastrocnemius muscle of emphysemic hamsters. The experimental animals had 2 different severities of lung damage from experimental emphysema induced by 20 mg/mL (E20) and 40 mg/mL (E40) papain.ResultsThe severity of emphysema increased significantly in E20 (60.52 ± 2.8, p < 0.05) and E40 (52.27 ± 4.7; crossed the alveolar intercepts) groups. As compared to the control group, there was a reduction on body (171.6 ± 15.9 g) and muscle weight (251.87 ± 24.87 mg) in the E20 group (157.5 ± 10.3 mg and 230.12 ± 23.52 mg, for body and muscle weight, respectively), which was accentuated in the E40 group (137.4 ± 7.2 g and 197.87 ± 10.49 mg, for body and muscle weight, respectively). Additionally, the thiobarbituric acid reactive substances (TBARS), tert-butyl hydroperoxide-initiated chemiluminescence (CL), carbonylated proteins, and chymotrypsin-like proteolytic activity were elevated in the E40 group as compared to the E20 group (p < 0.05 for all comparisons). The severity of emphysema significantly correlated with the progressive increase in CL (r = −0.95), TBARS (r = −0.98), carbonyl proteins (r = −0.99), and chymotrypsin-like proteolytic activity (r = −0.90). Furthermore, augmentation of proteolytic activity correlated significantly with CL (r = 0.97), TBARS (r = 0.96), and carbonyl proteins (r = 0.91).ConclusionsTaken together, the results of the present study suggest that muscle atrophy observed in this model of emphysema is mediated by increased muscle chymotrypsin-like activity, with possible involvement of oxidative stress in a severity-dependent manner.

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The objective of this study was to investigate whether emphysema induced by elastase or papain triggers the same effects on skeletal muscle, related to oxidative stress and proteolysis, in hamsters. For this purpose, we evaluated pulmonary lesions, body weight, muscle loss, oxidative stress (thiobarbituric acid-reactive substances, total and oxidized glutathiones, chemiluminescence stimulated by tert-butyl hydroperoxide and carbonyl proteins), chymotrypsin-like and calpain-like proteolytic activities and muscle fibre cross-sectional area in the gastrocnemius muscles of emphysemic hamsters. Two groups of animals received different intratracheal inductions of experimental emphysema: by 40 mg/ml papain (EP) or 5.2 IU/100 g animal (EE) elastase (n = 10 animals/group). The control group received intratracheal instillation of 300 μl sterile NaCl 0.9%. Compared with the control group, the EP group had reduced muscle weight (18.34%) and the EE group had increased muscle weight (8.37%). Additionally, tert-butyl hydroperoxide-initiated chemiluminescence, carbonylated proteins and chymotrypsin-like proteolytic activity were all elevated in the EP group compared to the CS group, while total glutathione was decreased compared to the EE group. The EE group showed more fibres with increased cross-sectional areas and increased calpain-like activity. Together, these data show that elastase and papain, when used to induce experimental models of emphysema, lead to different speeds and types of adaptation. These findings provide more information on choosing a suitable experimental model for studying skeletal muscle adaptations in emphysema.

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A avaliação da aptidão cardiorrespiratória é realizada através do consumo máximo de oxigênio (VO2máx), que é a medida mais difundida da aptidão aeróbia em indivíduos jovens e o melhor parâmetro fisiológico para avaliar a capacidade funcional do sistema cardiorrespiratório, geralmente mensurados, de forma direta, através da ergoespirometria. A fim de facilitar a avaliação do VO2máx, utilizam-se testes de campo, indiretos e de baixo custo financeiro, capazes de avaliar a capacidade de exercício como o “Incremental Shuttle Walk Test de 10 metros” (ISWT), desenvolvido baseando-se na distância máxima percorrida por um indivíduo através de um percurso padronizado. A partir do desempenho no teste, utilizam-se equações de predição de VO2máx para estimar a aptidão aeróbia. Portanto, o objetivo deste estudo foi determinar a validade do ISWT e reprodutibilidade de equações de predição para estimar o VO2máx em 50 jovens, do Centro de Ciências da Saúde – CCS da Universidade Estadual do Norte do Paraná (UENP), do sexo feminino, com idade entre 18 a 24 anos, não fumantes, e que não fossem suficientemente ativas ou atletas. As voluntárias foram submetidas ao teste de esforço máximo em esteira e campo. O VO2máx foi analisado de maneira indireta, utilizando-se diferentes tipos de equações através da distância percorrida no ISWT. Observou-se que, somente as equações de predição de Almeida et al. e a equação derivada de população brasileira (EB) reproduziram os valores do VO2máx obtidos na ergoespirometria, havendo correlação moderada entre as variáveis da equação de Almeida et al., com validade concorrente aceitável. Assim, podemos concluir que o ISWT apresentou validade para a população estudada e a equação proposta por Almeida et al. reproduziu os valores de VO2máx obtidos de forma direta, em mulheres jovens sedentárias.

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