Oxidative stress and skeletal muscle dysfunction are present in healthy smokers

Chronic exposure to cigarette smoke seems to be related to an increase of pro-inflammatory cytokines, oxidative stress and changes in muscular and physical performances of healthy smokers. However, these parameters have not yet been evaluated simultaneously in previous studies. The participants of this study were healthy males divided into two groups: smokers (n=20) and non-smokers (n=20). Inflammation was evaluated by measuring plasma levels of the cytokines IL-10, IL-6 e TNF-α, and of the soluble receptors sTNFR1 and sTNFR2. Oxidative stress was evaluated by determination of thiobarbituric acid reactive substances (TBARS) plasma levels, total antioxidant capacity of plasma and erythrocytes activity of the antioxidant enzymes superoxide dismutase (SOD) and catalase. Muscular performance was evaluated by measuring the peak torque of knee flexors and extensors, and by determining the total work of the knee extensors. Physical performance was assessed by measuring the peak oxygen uptake (VO2 peak), the maximum heart rate (HRmax) and the walking distance in the shuttle walking test. Smokers showed an increase in the levels of the sTNFR1 and TBARS and a decrease in the total antioxidant capacity of plasma, in the catalase activity and in the total work (P<0.05). IL-6, IL-10, sTNFR2, SOD, peak torque, VO2 peak, HRmax and walking distance were similar between groups. Smokers presented increased oxidative stress and skeletal muscle dysfunction, demonstrating that the changes in molecular and muscular parameters occur simultaneously in healthy smokers.

长期暴露于香烟烟雾，与健康吸烟者体内促炎细胞因子水平升高、氧化应激增强，以及肌肉与躯体运动表现改变存在关联。然而，既往研究尚未同时对上述多项指标开展综合评估。本研究纳入40名健康男性受试者，分为吸烟组（n=20）与非吸烟组（n=20）。炎症状态通过检测血浆中细胞因子IL-10、IL-6、TNF-α以及可溶性受体sTNFR1、sTNFR2的水平进行评估；氧化应激水平则通过测定血浆硫代巴比妥酸反应物质（thiobarbituric acid reactive substances, TBARS）水平、血浆总抗氧化能力，以及红细胞内抗氧化酶超氧化物歧化酶（superoxide dismutase, SOD）与过氧化氢酶（catalase）的活性进行评估；肌肉运动表现通过检测膝关节屈肌与伸肌的峰力矩，以及膝关节伸肌的总做功量进行评估；躯体运动表现则通过检测峰值摄氧量（peak oxygen uptake, VO₂ peak）、最大心率（maximum heart rate, HRmax）以及往返步行试验中的步行距离进行评估。与非吸烟组相比，吸烟组受试者的血浆sTNFR1与TBARS水平显著升高，血浆总抗氧化能力、过氧化氢酶活性及膝关节伸肌总做功量均显著降低（P<0.05）。两组受试者的IL-6、IL-10、sTNFR2水平，SOD活性、膝关节峰力矩、峰值摄氧量、最大心率及步行距离均无显著差异。吸烟组受试者存在氧化应激增强与骨骼肌功能障碍，证实健康吸烟者体内分子与肌肉相关指标的改变可同时出现。