Bazzy A R, Kim Y J
Department of Pediatrics, Yale University School of Medicine, New Haven, Connecticut 06510.
J Appl Physiol (1985). 1992 Jan;72(1):266-71. doi: 10.1152/jappl.1992.72.1.266.
To determine whether the increase in oxidative capacity after respiratory muscle training with chronic inspiratory loads in sheep is specific to a particular fiber type, we measured cytochrome c oxidase (COX) activity in type I and type II fibers. COX activity in individual fibers was examined histochemically and measured as relative optical density by use of an image processing system. Fiber types were differentiated by the myosin adenosine-triphosphatase reaction. We found that COX activity was higher in both fiber types in the trained diaphragms than in the control diaphragms (P less than 0.01). The increase with training was greater in type II (39%) than in type I fibers (21%), resulting in relatively homogeneous COX activity in all diaphragmatic fibers. The proportion of type I fibers increased from 43.4 +/- 5.4% in the control diaphragm to 53.1 +/- 2.9% in the trained diaphragm, whereas the proportion of type II fibers decreased (P less than 0.001). We conclude that respiratory muscle training activates oxidative enzyme activity in both diaphragmatic fiber types; this activation is differentially more in type II fibers, which also decrease in proportion, and less in type I fibers, which increase in proportion.
为了确定绵羊在慢性吸气负荷下进行呼吸肌训练后氧化能力的增加是否特定于某一特定纤维类型，我们测量了I型和II型纤维中的细胞色素c氧化酶（COX）活性。通过组织化学方法检查单个纤维中的COX活性，并使用图像处理系统以相对光密度进行测量。通过肌球蛋白三磷酸腺苷酶反应区分纤维类型。我们发现，训练后的膈肌中两种纤维类型的COX活性均高于对照膈肌（P<0.01）。训练后II型纤维（39%）的增加幅度大于I型纤维（21%），导致所有膈肌纤维中的COX活性相对均匀。I型纤维的比例从对照膈肌中的43.4±5.4%增加到训练后膈肌中的53.1±2.9%，而II型纤维的比例则下降（P<0.001）。我们得出结论，呼吸肌训练可激活两种膈肌纤维类型中的氧化酶活性；这种激活在II型纤维中差异更大，其比例也下降，而在I型纤维中则较小，其比例增加。
