Rates of force generation in Drosophila fast and slow muscle types have opposite responses to phosphate.
Rates of force generation in Drosophila fast and slow muscle types have opposite responses to phosphate.
复制标题
果蝇快肌和慢肌类型的力产生速率对磷酸盐有相反的反应。
DOI：
10.1007/978-1-4419-9029-7_42
复制
发表时间：
2003
影响因子：
--
通讯作者：
Maughan,DavidW
中科院分区：
文献类型：
--
作者：
Swank,DouglasM;Maughan,DavidW
横纹肌的功能多样性，以满足不同的运动需求是由于不同的肌球蛋白亚型。（1965），他们是最早研究肌球蛋白同种型的生理相关性的人之一，证明了各种肌肉类型中的不同收缩速度与肌动蛋白激活的肌球蛋白ATP酶相关。（1985）、（1987）和（1988）等通过显示肌肉速度与肌球蛋白同种型组成相关来扩展这些研究。最近，（2002）通过在间接飞行肌（IFM）中用慢速胚胎肌球蛋白（表示为EMB）替代天然快速成人IFM肌球蛋白（表示为IFI），直接证明肌球蛋白亚型是纤维动力学差异的主要决定因素（图1）。替代EMB同种型将IFM从在高频率下产生最大振荡功的肌肉转变为产生更多功但频率低得多的肌肉（图2，在Swank等人，2002年）。同种型取代使钙激活的等长张力（To）增强近3倍，但使最大振荡功率（Pmax，等于振荡功乘以频率）降低至仅为IFI纤维的25%（Swank等人，2002年）。在EMB光纤中，在频率（1020 Hz）下实现的Tmax显著低于在IFI光纤中实现的Pmax（10150 Hz，即，在15°C时的翅拍频率）。在飞行系统的谐振频率（即，在± 150 Hz）时，没有产生功率，从而解释了EMB线路飞行能力的丧失。因此，EMB替代IFI类似于将肌肉从快速纤维类型转换为慢速纤维类型。
Much of the functional diversity of striated muscle that serves to meet different locomotory demands is due to different isoforms of myosin. (1965), who were among the first to investigate the physiological relevance of myosin isoforms, demonstrated that different speeds of contraction in various muscle types correlate with actin-activated myosin ATPase. (1985), (1987), and (1988), among others, extended these studies by showing muscle speeds correlate with myosin isoform composition. Recently, (2002) directly proved that myosin isoforms are the prime determinants of fiber kinetic differences by substituting the slow embryonic myosin (denoted EMB) for the native, fast adult IFM myosin (denoted IFI) in the indirect flight muscle (IFM) (Fig 1). Substituting the EMB isoform transformed the IFM from a muscle that generates maximum oscillatory work at high frequencies, to one that generates more work, but at much lower frequencies (Fig. 2, after Swank et al., 2002). The isoform substitution enhances calcium-activated isometric tension (To) nearly 3-fold, but reduces maximum oscillatory power (Pmax, equal to oscillatory work times frequency) to only ∼25% that of IFI fibers (Swank et al., 2002). In EMB fibers Tmaxachieved at a frequency (∼20 Hz) that is considerably lower than that at which Pmaxis achieved in IFI fibers (∼150 Hz, i.e., the wing beat frequency at 15°C). At the resonant frequency of the flight system (i.e., at ∼ 150 Hz), no power is produced, thereby explaining the loss of flight ability in the EMB lines. Thus substitution of EMB for IFI is akin to converting the muscle from a fast fiber type to a slow fiber type.