大鼠与家兔生后发育期趾浅屈肌纤维间的比较

肌纤维的分类建立在它们所含有的不同肌球蛋白重链(MHC)异构体基础上,对大鼠和家兔生后发育各年龄阶段趾浅屈肌采用标准的肌动球蛋白ATP酶和琥珀酸脱氢酶组织化学染色。在生后2周龄至24周龄的大鼠和家兔,I型和ⅡⅩ型肌纤维百分比例趋于减少,而ⅡA型和ⅡB型纤维百分比例则增加。进行大量单肌纤维的组织化学特征的比较和肌纤维间相关性探讨,结果表明,动物平均体重与趾浅屈肌的平均湿重随着生后发育逐渐增加。Ⅰ,ⅡⅩ,ⅡA型和ⅡB型纤维均在生后各年龄组的全部肌肉内被发现,但生后2日龄组是个例外。在生后发育期间,雄性大鼠和家兔ⅡB型纤维的平均肌纤维型构成要大于雌性大鼠和家兔,而雄性大鼠和家兔Ⅰ,ⅡⅩ型和ⅡA型3种氧化组织化学分类的肌纤维型构成均小于雌性大鼠和家兔。大鼠Ⅰ,ⅡⅩ,ⅡA型和ⅡB型纤维的平均横切面积明显小于家兔的同类型肌纤维,在大鼠和家兔可见明显的性别差异。在大鼠和家兔的ⅡⅩ型纤维横切面积是最小的,Ⅰ型和ⅡA型纤维呈中等大小横切面积,ⅡB型纤维横切面积最大。此研究有助于我们尝试研究啮齿类动物快肌纤维生理特征的适应性。

The Comparison of Digitorum Superficialis Flexor Muscle Fibers Between Rats and Rabbits During Postnatal Development

The distribution of muscle fibers classified on the basis of their content of different myosin heavy chain (MHC) isoforms was analysed in muscle samples from the digitorum superficialis flexor muscles of postnatal different ages of rats and rabbits by correlating standard actomyosin ATPase and succinic dehydrogenase SDHase histochemistry.The percentage of type Ⅰ,ⅡⅩ fibers of rats and rabbits decreased whereas that for type ⅡA,ⅡB fibers increased from postnatal 2-week to 24-week old.The histochemical characterization of larger number of single fibers was compared and correlated on a fiber-to-fiber basis.The results showed that the mean body weight and the average wet weight of the digitorum superficialis flexor muscles were gradually increased with postnatal development.Type Ⅰ,ⅡⅩ,ⅡA and ⅡB fibers were found in all muscles of different groups except 2 days.Mean fiber type compositions of type ⅡB fiber of male rats and rabbits were larger than that of female rats and rabbits during postnatal development.Three oxidative histochemically-classified fiber compositions of type Ⅰ,ⅡⅩ,ⅡA fiber in male rats and rabbits were smaller than that of female.The mean transverse-sectional areas of type Ⅰ, ⅡⅩ, ⅡA and ⅡB fiber in rats were significantly smaller than those of rabbits. There were evident sexual distinction of rats and rabbits.In rats and rabbits,Type ⅡⅩ fiber had the smallest cross-sectional area.Type Ⅰ, ⅡA fibers had the intermediate area and type ⅡB fibers had the largest. This has important implications in attempts to study the physiological properties of fast fiber types adequately in rodents.