Sutherland H, Jarvis J C, Kwende M M, Gilroy S J, Salmons S
Department of Human Anatomy and Cell Biology, University of Liverpool, UK.
Muscle Nerve. 1998 Dec;21(12):1632-46. doi: 10.1002/(sici)1097-4598(199812)21:12<1632::aid-mus3>3.0.co;2-w.
Rabbit tibialis anterior muscles were stimulated continuously at 2.5 Hz, 5 Hz, or 10 Hz for 10 months. The resulting adaptive transformation was dose-related for contractile speed, myosin isoform composition, and enzyme activities. The "fast-oxidative" state produced by stimulation at 2.5 Hz was stable: even after 10 months, 84% of the fibers were of type 2A. Absence of a secondary decline in oxidative activity in these muscles provided strong evidence of a causal link between myosin transitions and metabolic adaptation. Significant fiber loss occurred only after prolonged stimulation at 10 Hz. The myosin isoform composition of individual muscles stimulated at 5 Hz resembled that of muscles stimulated at either the lower or the higher frequency, behavior consistent with a threshold for fiber type change. In clinical applications such as cardiomyoplasty, muscles could be used more effectively by engineering their properties to combine speed and power of contraction with the necessary resistance to fatigue.
对兔胫前肌分别以2.5Hz、5Hz或10Hz的频率持续刺激10个月。由此产生的适应性转变在收缩速度、肌球蛋白同工型组成和酶活性方面与刺激剂量相关。以2.5Hz刺激产生的“快速氧化”状态是稳定的：即使在10个月后，84%的纤维仍为2A型。这些肌肉中氧化活性没有二次下降，这有力地证明了肌球蛋白转变与代谢适应之间存在因果关系。仅在以10Hz长时间刺激后才出现明显的纤维损失。以5Hz刺激的单个肌肉的肌球蛋白同工型组成类似于以较低或较高频率刺激的肌肉，这种行为与纤维类型变化的阈值一致。在诸如心肌成形术等临床应用中，通过设计肌肉特性，使其将收缩速度和力量与必要的抗疲劳能力相结合，肌肉可以得到更有效的利用。
