Harrison A P, Latorre R, Dauncey M J
Department of Cellular Physiology, The Babraham Institute, Cambridge, England.
Reprod Fertil Dev. 1997;9(7):731-40. doi: 10.1071/r97026.
Marked changes in muscle function occur after birth, with the response being dependent on developmental stage. Therefore, postnatal cellular ontogeny of functionally distinct skeletal muscles was investigated in the pig, a large mammal born at a relatively advanced stage of development. Assessment of myofibre contractile (type I slow/type II fast) and metabolic (oxidative/glycolytic) properties at Days 0, 2, 5 and 14 revealed type-specific differences in hypertrophy and differentiation. Type I fibre proportions increased significantly in soleus and diaphragm, especially between Days 0 and 5, and rhomboideus showed a similar trend, but in longissimus there was a slight decrease during Days 0-2. Cytochrome oxidase activity was relatively high and similar among myofibres in all muscles at birth, and fibres with low activity were not detected until Day 5. In contrast with previous reports, glycolytic fibres were present in all muscles at birth; postnatal changes in alpha-glycerophosphate dehydrogenase activity were both muscle- and myofibre-specific. Hence, although myosin ATPase activity and metabolic properties of porcine myofibres are well developed at birth, they continue to mature postnatally. This suggests that postnatal muscle development can be modulated by extrinsic factors, even in mammals born at a relatively advanced stage of development.
出生后肌肉功能会发生显著变化，其反应取决于发育阶段。因此，在猪这种发育阶段相对较高级的大型哺乳动物中，研究了功能不同的骨骼肌的产后细胞个体发育。在第0、2、5和14天对肌纤维的收缩特性（I型慢肌/II型快肌）和代谢特性（氧化型/糖酵解型）进行评估，结果显示在肥大和分化方面存在类型特异性差异。比目鱼肌和膈肌中I型纤维比例显著增加，尤其是在第0天到第5天之间，菱形肌也呈现类似趋势，但在第0 - 2天期间，背最长肌中I型纤维比例略有下降。出生时所有肌肉中肌纤维的细胞色素氧化酶活性相对较高且相似，直到第5天才检测到低活性的纤维。与之前的报道相反，出生时所有肌肉中均存在糖酵解纤维；α - 甘油磷酸脱氢酶活性的产后变化具有肌肉和肌纤维特异性。因此，尽管猪肌纤维的肌球蛋白ATP酶活性和代谢特性在出生时已发育良好，但它们在出生后仍会继续成熟。这表明即使在发育阶段相对较高级的哺乳动物中，产后肌肉发育也可受外在因素调节。
