Fratacci M D, Levame M, Rauss A, Bousbaa H, Atlan G
Institut National de la Santé et de la Recherche Médicale U296, Créteil, France.
Reprod Fertil Dev. 1996;8(3):391-8. doi: 10.1071/rd9960391.
The changes occurring in the histochemical characteristics of the rat diaphragm during the postnatal period were examined. Fibre-type distribution, fibre oxidative capacity, i.e. succinate-dehydrogenase (SDH) activity, and cross-sectional area were compared in the costal (COS) and crural (CRU) regions, and across their abdominal and thoracic surfaces. The proportions of type I and IIb fibres in both COS and CRU increased with age, while the proportion of type IIa fibres progressively decreased. For COS, fibre distribution was homogeneous over the entire muscle and did not change after 4 weeks. For CRU, it was heterogeneous with a higher proportion of type I fibres on the thoracic surface as from the first week. All fibre types significantly increased in cross-sectional area between 1 and 8 weeks, with no significant differences in COS and CRU. Mean SDH activity did not differ between COS and CRU or across the muscles. Mean SDH activitiĕs-were low and identical in all fibre types at birth, and then increased, peaking at the 6th week in type I and IIa fibres. When total muscle fibre oxidative capacity was calculated from an index including fibre-type proportion, cross-sectional area and mean SDH activity, it was significantly higher at 1 than at 8 weeks after birth; this might have functional implications for the newborn.
研究了大鼠膈肌在出生后阶段组织化学特征的变化。比较了肋部（COS）和膈脚部（CRU）区域及其腹部和胸部表面的纤维类型分布、纤维氧化能力，即琥珀酸脱氢酶（SDH）活性以及横截面积。COS和CRU中I型和IIb型纤维的比例均随年龄增加，而IIa型纤维的比例逐渐降低。对于COS，整个肌肉的纤维分布均匀，4周后无变化。对于CRU，其分布不均一，从第一周起胸部表面I型纤维比例更高。1至8周期间所有纤维类型的横截面积均显著增加，COS和CRU之间无显著差异。COS和CRU之间或整个肌肉的平均SDH活性无差异。出生时所有纤维类型的平均SDH活性均较低且相同，随后升高，在I型和IIa型纤维中于第6周达到峰值。当根据包括纤维类型比例、横截面积和平均SDH活性的指数计算总肌纤维氧化能力时，出生后1周时显著高于8周；这可能对新生儿具有功能意义。
