UCD School of Medicine and Medical Science, Health Sciences Centre, University College Dublin, Dublin, Ireland.
Respiration. 2011;82(6):539-49. doi: 10.1159/000332348. Epub 2011 Oct 11.
Age, obesity and male sex are risk factors for the development of obstructive sleep apnoea syndrome.
We examined structural and functional properties of the sternohyoid muscle in young lean and aged obese male rats. We hypothesized that the aged muscle would be vulnerable to oxidative stress (hypoxia).
Isometric contractile and endurance properties of the sternohyoid muscle were assessed in vitro with or without the superoxide scavenger Tempol (10 mM). Muscle fibre size and density were determined by myosin heavy chain immunofluorescence. Succinate dehydrogenase (SDH) and glycerol-3- phosphate dehydrogenase (GPDH) enzyme activities were determined.
Fibre hypertrophy, increased fast twitch (type 2X) fibre density, decreased SDH activity and increased GPDH activity, together with increased force and fatigue, were observed in aged obese muscles compared to young lean muscles. Tempol treatment increased strength and sensitivity to stimulation. Hypoxic depression of force was ameliorated by antioxidant treatment with equivalent effects in young lean and aged obese muscle.
We conclude that the rat sternohyoid exhibits indefinite growth and is protected from oxidative stress as the animal ages.
年龄、肥胖和男性是发生阻塞性睡眠呼吸暂停综合征的危险因素。
我们研究了年轻瘦大鼠和老年肥胖雄性大鼠胸锁乳突肌的结构和功能特性。我们假设老年肌肉易受氧化应激（缺氧）的影响。
在体外使用或不使用超氧化物清除剂 Tempol（10 mM）评估胸锁乳突肌的等长收缩和耐力特性。通过肌球蛋白重链免疫荧光法测定肌纤维大小和密度。测定琥珀酸脱氢酶（SDH）和甘油-3-磷酸脱氢酶（GPDH）酶活性。
与年轻瘦肌肉相比，老年肥胖肌肉表现出纤维肥大、快肌（2X 型）纤维密度增加、SDH 活性降低和 GPDH 活性增加，同时力量和疲劳增加。Tempol 处理增加了力量和刺激敏感性。抗氧化剂处理减轻了缺氧对力量的抑制作用，在年轻瘦肌肉和老年肥胖肌肉中具有等效作用。
我们得出结论，大鼠胸锁乳突肌表现出无限生长，并随着年龄的增长而免受氧化应激的影响。
