高原鼢鼠和高原鼠兔骨骼肌摄氧功能差异

Difference in oxygen uptake in skeletal muscles between plateau zokor(Myospalax rufescens baileyi)and plateau pika(Ochotona curzoniac)

为了探讨高原鼢鼠和高原鼠兔骨骼肌摄氧功能与其生活习性的关系,以Sprague-Dawley(SD)大鼠为对照,应用免疫组织化学方法测定三种动物骨骼肌微血管密度(microvessel density,MVD);以显微体视学技术测量线粒体的数量和面积;用实时定量PCR检测三种动物骨骼肌肌红蛋白(myoglobin,Mb)mRNA水平,并用分光光度法测定了三种动物骨骼肌Mb含量。结果显示:高原鼠兔骨骼肌中MVD、线粒体数量和面积均显著低于高原鼢鼠和SD大鼠(P<0.05);高原鼢鼠和高原鼠兔骨骼肌中Mb的mRNA水平均显著高于SD大鼠(P<0.05),而二者之间无明显差异;两种高原动物骨骼肌Mb含量也显著高于SD大鼠(P<0.05),并且高原鼢鼠骨骼肌Mb含量显著高于高原鼠兔(P<0.05)。上述结果表明,高原鼢鼠尽管生活在严重的低氧环境中,但其骨骼肌以红肌纤维为主,肌肉组织MVD高、线粒体数量多、总表面积大、Mb的mRNA水平及蛋白含量高,表明高原鼢鼠骨骼肌获氧能力强,有氧获能水平高,主要以有氧呼吸为主;与之相反,高原鼠兔骨骼肌以白肌纤维为主,MVD低,线粒体数目少、总表面积小,Mb含量相对高原鼢鼠较低,提示高原鼠兔骨骼肌主要以糖酵解获能。以上这些差异不仅与两种动物的种属不同有关,而且可能与不同的生活习性密切相关。

To investigate the difference between the functions of oxygen uptake in skeletal muscle and living habits of plateau zokor （Myospalax rufescens baileyi） and plateau pika （Ochotona curzoniac）, the microvessel densities （MVD） of skeletal muscle of plateau zokor, plateau pika and Sprague-Dawley （SD） rat were measured by immunohistochemical staining; the numerical density on area （NA） of mitochondria, and surface density （Sv, external surface area density of mitochondria per unit volume of skeletal muscle fiber） were obtained by stereo microscope technique; mRNA levels of myoglobin （Mb） in skeletal muscle were determined by real-time PCR, and the contents of Mb protein in skeletal muscle were determined by spectro-photometer. The results showed that MVD, NA and Sv of mitochondria in skeletal muscle of plateau pika were significantly lower than those of plateau zokor and SD rat （P〈0.05）. The mRNA levels of Mb gene in skeletal muscle of plateau zokor and plateau pika were notably higher than that of SD rat （P〈0.05）. There were significant differences in the contents of Mb among these three species, and plateau zokor and SD rat presented the highest and the lowest value, respectively （P〈0.05）. The results suggest that even though plateau zokor inhabits in the hypoxia environment, most of its skeletal muscle fiber are red muscle fiber. While most of skeletal muscle fibers of plateau pika are white muscle fibers. This kind of white muscle has low MVD, NA and Sv of mitochondria and less content of Mb compared with the red one, suggesting it obtains most energy from aerobic oxidation. The above-mentioned differences in skeletal muscles may be related to not only the different species, but also the different living habits of these two high altitude species.