Anzueto A, Brassard J M, Andrade F H, Lawrence R A, Maxwell L C, Levine S M, Jenkinson S G
Department of Medicine, University of Texas Health Science Center at San Antonio.
J Appl Physiol (1985). 1994 Jul;77(1):63-8. doi: 10.1152/jappl.1994.77.1.63.
The association of oxygen radical generation with impaired diaphragm performance has previously been reported after inspiratory resistive loading (IRL). We hypothesized that exposure of rats to normobaric hyperoxia (O2) could produce impaired diaphragm function because of free radical production. Sprague-Dawley rats were divided into four groups: 1) room air (control), 2) > 95% O2 for 24 h, 3) > 95% O2 for 48 h, and 4) > 95% O2 for 60 h. Each group was studied at rest after the O2 exposure and then after IRL. During IRL, the animals breathed through an inspiratory resistor until they were unable to sustain > 70% of the maximum airway pressure. Diaphragm samples were obtained for analysis of glutathione (GSH) and glutathione disulfide (GSSG) concentrations. In vitro isometric contractile properties were also determined, including maximal tetanic tension (Po) and maximal twitch tension (Pt), in GSSG content and in GSSG-to-GSH ratios. Hyperoxia for > 48 h resulted in significant decreases in Po and Pt and an increase in GSSG content and in GSSG-to-GSH ratios compared with other groups. Those same animals subjected to IRL showed a further decrease in Po and Pt. These data suggest that free radical generation may occur in the diaphragm during a hyperoxia exposure associated with activation of the GSH redox cycle and impairment of diaphragm function.
先前有报道称，在吸气阻力负荷（IRL）后，氧自由基生成与膈肌功能受损有关。我们假设，将大鼠暴露于常压高氧环境（O2）中会因自由基产生而导致膈肌功能受损。将Sprague-Dawley大鼠分为四组：1）室内空气（对照组），2）> 95% O2 24小时，3）> 95% O2 48小时，4）> 95% O2 60小时。每组在O2暴露后休息时进行研究，然后在IRL后进行研究。在IRL期间，动物通过吸气阻力器呼吸，直到它们无法维持最大气道压力的> 70%。获取膈肌样本以分析谷胱甘肽（GSH）和谷胱甘肽二硫化物（GSSG）浓度。还测定了体外等长收缩特性，包括最大强直张力（Po）和最大抽搐张力（Pt）、GSSG含量以及GSSG与GSH的比率。与其他组相比，> 48小时的高氧导致Po和Pt显著降低，GSSG含量以及GSSG与GSH的比率增加。那些接受IRL的相同动物的Po和Pt进一步降低。这些数据表明，在与GSH氧化还原循环激活和膈肌功能受损相关的高氧暴露期间，膈肌中可能会产生自由基。
