Supinski G, Nethery D, Murhez N, Ciufo R, DiMarco A
Department of Medicine, Case Western Reserve University, Cleveland, OH, USA.
J Appl Physiol (1985). 1996 Sep;81(3):1362-9. doi: 10.1152/jappl.1996.81.3.1362.
Several studies have shown that loaded breathing elicits an oxidation of reduced glutathione (GSH) to oxidized glutathione (GSSG) within the diaphragm, but the effects of loaded breathing on GSH and GSSG levels in other respiratory muscles have not been examined. The present experiment examined this issue by using decerebrate unanesthetized rats in which a large inspiratory resistive load was applied until respiratory arrest. Subsequently, muscle samples from the triangularis sterni, diaphragm (Dia), parasternal intercostal (PI), upper rib cage lateral intercostal, lower rib cage lateral intercostal, and soleus were assayed for GSH and GSSG. Glutathione levels were also measured on samples from unloaded control animals. We found that the Dia from loaded animals had a lower GSH level than did control animals (i.e., 653 +/- 99 and 928 +/- 40 nmol/gm for loaded and control groups, respectively; P < 0.05), higher GSSG level (68 +/- 14 and 32 &/- 7 nmol/gm for loaded and control groups, respectively; P < 0.05), and higher GSSG-to-GSH ratios (GSSG/GSH; 17.0 +/- 6.0 and 3.7 +/- 0.9% for loaded and control groups, respectively; (P <0.05). Of the other muscles examined, only the PI muscles had comparable alterations in glutathione levels in response to loading. Specifically, for the PI muscles of loaded and control groups, GSH was 427 +/- 75 and 618 +/- 40 nmol/g, (P < 0.05), GSSG was 71 +/- 16 and 20 +/- 5 nmol/g (P < 0.01), and GSSG/GSH was 22 +/- 8 and 3.6 +/- 1.2%, respectively (P < 0.05). No other muscle demonstrated a significant increase in GSSG or GSSG/GSH with loading, and only the lower rib cage lateral intercostal had a significant reduction in GSH. These findings indicate variation in the degree of glutathione oxidation elicited by inspiratory loading among the different respiratory muscles. The fact that quantitatively similar glutathione alterations were observed in the Dia and PI muscles suggests that these muscle groups may share a similar propensity to generate free radicals during inspiratory loading.
多项研究表明，负荷呼吸会引起膈肌内还原型谷胱甘肽（GSH）氧化为氧化型谷胱甘肽（GSSG），但负荷呼吸对其他呼吸肌中GSH和GSSG水平的影响尚未得到研究。本实验通过对去大脑未麻醉大鼠施加较大的吸气阻力负荷直至呼吸停止来研究这一问题。随后，对胸骨三角肌、膈肌（Dia）、胸骨旁肋间肌（PI）、上胸廓外侧肋间肌、下胸廓外侧肋间肌和比目鱼肌的肌肉样本进行GSH和GSSG检测。还对未负荷对照动物的样本进行了谷胱甘肽水平检测。我们发现，负荷动物的膈肌GSH水平低于对照动物（即负荷组和对照组分别为653±99和928±40 nmol/g；P<0.05），GSSG水平较高（负荷组和对照组分别为68±14和32±7 nmol/g；P<0.05），GSSG与GSH的比值（GSSG/GSH）也较高（负荷组和对照组分别为17.0±6.0和3.7±0.9%；P<0.05）。在检测的其他肌肉中，只有PI肌在负荷时谷胱甘肽水平有类似变化。具体而言，负荷组和对照组的PI肌中，GSH分别为427±75和618±40 nmol/g（P<0.05），GSSG分别为71±16和20±5 nmol/g（P<0.01），GSSG/GSH分别为22±8和3.6±1.2%（P<0.05）。没有其他肌肉在负荷时GSSG或GSSG/GSH有显著增加，只有下胸廓外侧肋间肌的GSH有显著降低。这些发现表明，不同呼吸肌在吸气负荷引起的谷胱甘肽氧化程度上存在差异。在膈肌和PI肌中观察到定量相似的谷胱甘肽变化，这一事实表明这些肌肉群在吸气负荷期间可能具有相似的产生自由基的倾向。
