Pellegrino M A, Canepari M, Rossi R, D'Antona G, Reggiani C, Bottinelli R
Department of Experimental Medicine, Human Physiology Unit, University of Pavia, Pavia, Italy.
J Physiol. 2003 Feb 1;546(Pt 3):677-89. doi: 10.1113/jphysiol.2002.027375.
Maximum shortening velocity (V(0)) was determined in single fibres dissected from hind limb skeletal muscles of rabbit and mouse and classified according to their myosin heavy chain (MHC) isoform composition. The values for rabbit and mouse V(0) were compared with the values previously obtained in man and rat under identical experimental conditions. Significant differences in V(0) were found between fibres containing corresponding myosin isoforms in different species: as a general rule for each isoform V(0) decreased with body mass. Myosin isoform distributions of soleus and tibialis anterior were analysed in mouse, rat, rabbit and man: the proportion of slow myosin generally increased with increasing body size. The diversity between V(0) of corresponding myosin isoforms and the different myosin isoform composition of corresponding muscles determine the scaling of shortening velocity of whole muscles with body size, which is essential for optimisation of locomotion. The speed of actin translocation (V(f)) in in vitro motility assay was determined with myosins extracted from single muscle fibres of all four species: significant differences were found between myosin isoforms in each species and between corresponding myosin isoforms in different species. The values of V(0) and V(f) determined for each myosin isoform were significantly correlated, strongly supporting the view that the myosin isoform expressed is the major determinant of maximum shortening velocity in muscle fibres.
测定了从兔和小鼠后肢骨骼肌分离出的单根肌纤维的最大缩短速度（V(0)），并根据其肌球蛋白重链（MHC）同工型组成进行分类。将兔和小鼠的V(0)值与之前在相同实验条件下在人和大鼠中获得的值进行比较。发现在不同物种中含有相应肌球蛋白同工型的纤维之间V(0)存在显著差异：一般来说，每种同工型的V(0)随体重下降。分析了小鼠、大鼠、兔和人中比目鱼肌和胫骨前肌的肌球蛋白同工型分布：慢肌球蛋白的比例通常随体型增大而增加。相应肌球蛋白同工型的V(0)差异以及相应肌肉不同的肌球蛋白同工型组成决定了全肌缩短速度随体型的缩放，这对于优化运动至关重要。用从所有四个物种的单根肌纤维中提取的肌球蛋白测定了体外运动测定中的肌动蛋白转运速度（V(f)）：在每个物种的肌球蛋白同工型之间以及不同物种的相应肌球蛋白同工型之间发现了显著差异。为每种肌球蛋白同工型测定的V(0)和V(f)值显著相关，有力地支持了所表达的肌球蛋白同工型是肌纤维最大缩短速度的主要决定因素这一观点。
