Borzone G, Julian M W, Merola A J, Clanton T L
Department of Internal Medicine, Ohio State University, Columbus 43210.
J Appl Physiol (1985). 1994 Jun;76(6):2825-31. doi: 10.1152/jappl.1994.76.6.2825.
It has been suggested that oxidant stress may contribute to dysfunction of respiratory muscles undergoing severe work loads. We examined changes in glutathione content and redox status in the diaphragm and intercostal muscles of anesthetized Sprague-Dawley rats exposed to prolonged inspiratory resistive loading while breathing 70% O2. These results were compared with those from control groups breathing air or 70% O2. Changes in liver glutathione were also examined. Freeze-clamping and an enzymatic recycling assay were used. Results show that 1) in controls, glutathione content was higher in the diaphragm than in the intercostals, 2) severe hypercapnic acidosis without hypoxemia was present with loading, 3) total diaphragm glutathione decreased approximately 35% with no increase in glutathione oxidation with resistive breathing, whereas intercostal and liver glutathione remained unchanged, and 4) the drop in diaphragm glutathione correlated significantly with the drop in minute ventilation and the increase in arterial PCO2, whereas it was not directly related to intensity of respiratory muscle activity. In conclusion, although diaphragm susceptibility to oxidant stress may be increased with resistive breathing, it is unlikely that the modest decrease in total glutathione contributed significantly to respiratory failure in this model.
有人提出，氧化应激可能导致承受重度工作负荷的呼吸肌功能障碍。我们检测了在吸入70%氧气的情况下，长时间接受吸气阻力负荷的麻醉状态下的Sprague-Dawley大鼠膈肌和肋间肌中谷胱甘肽含量及氧化还原状态的变化。将这些结果与呼吸空气或70%氧气的对照组结果进行比较。还检测了肝脏谷胱甘肽的变化。采用冷冻钳夹和酶循环测定法。结果显示：1）在对照组中，膈肌中的谷胱甘肽含量高于肋间肌；2）负荷时出现无低氧血症的严重高碳酸血症酸中毒；3）膈肌总谷胱甘肽减少约35%，阻力呼吸时谷胱甘肽氧化无增加，而肋间肌和肝脏谷胱甘肽保持不变；4）膈肌谷胱甘肽的下降与分钟通气量的下降及动脉血二氧化碳分压的升高显著相关，而与呼吸肌活动强度无直接关系。总之，尽管阻力呼吸可能增加膈肌对氧化应激的易感性，但在该模型中，总谷胱甘肽的适度减少不太可能显著导致呼吸衰竭。
