Sieck G C, Sacks R D, Blanco C E
Department of Anatomy, University of California School of Medicine, Los Angeles 90024.
J Appl Physiol (1985). 1987 Sep;63(3):1076-82. doi: 10.1152/jappl.1987.63.3.1076.
The oxidative capacity and cross-sectional area of muscle fibers were compared between the costal and crural regions of the cat diaphragm and across the abdominal-thoracic extent of the muscle. Succinate dehydrogenase (SDH) activity of individual fibers was quantified using a microphotometric procedure implemented on an image-processing system. In both costal and crural regions, population distributions of SDH activities were unimodal for both type I and II fibers. The continuous distribution of SDH activities for type II fibers indicated that no clear threshold exists for the subclassification of fibers based on differences in oxidative capacity (e.g., the classification of fast-twitch glycolytic and fast-twitch oxidative glycolytic fiber types). No differences in either SDH activity or cross-sectional area were noted between fiber populations of the costal and crural regions. Differences in SDH activity and cross-sectional area were noted, however, between fiber populations located on the abdominal and thoracic sides of the costal region. Both type I and II fibers on the abdominal side of the costal diaphragm were larger and more oxidative than comparable fibers on the thoracic side.
对猫膈肌的肋部和腿部区域以及整个肌肉的胸腹范围的肌纤维氧化能力和横截面积进行了比较。使用图像处理系统上实施的显微光度法对单个纤维的琥珀酸脱氢酶（SDH）活性进行了量化。在肋部和腿部区域，I型和II型纤维的SDH活性总体分布均为单峰。II型纤维SDH活性的连续分布表明，基于氧化能力差异（例如，快肌糖酵解和快肌氧化糖酵解纤维类型的分类）对纤维进行亚分类不存在明确的阈值。肋部和腿部区域的纤维群体之间在SDH活性或横截面积方面均未发现差异。然而，在肋部区域的腹部和胸部侧的纤维群体之间，观察到了SDH活性和横截面积的差异。肋部膈肌腹部侧的I型和II型纤维均比胸部侧的同类纤维更大且氧化能力更强。
