Epitrochlearis muscle. I. Mechanical performance, energetics, and fiber composition.
Epitrochlearis muscle. I. Mechanical performance, energetics, and fiber composition.
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滑车上肌。
DOI：
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发表时间：
1980
影响因子：
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通讯作者：
D. Kipnis
中科院分区：
文献类型：
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作者：
R. Nesher;I. Karl;K. Kaiser;D. Kipnis
描述了一种体外大鼠肌肉制备物，其可以以12-240次抽搐/分钟的速率收缩。最大dF/dt与最大抽搐张力，对于12-120次抽搐/分钟的收缩速率，它们的比率恒定在约8 ms。达到峰值张力的时间为8-13 ms，达到峰值dF/dt的时间为5-8 ms，和半弛豫时间4毫秒。这些参数不受收缩率或等长收缩的持续时间。差示ATP酶染色显示60-65%的纤维为快缩白色，20%为快缩红色，15%为慢缩红色。快缩纤维的优势与所观察到的肌肉的机械性能。以高达48次抽搐/分钟的速率收缩60分钟的肌肉将总腺嘌呤核苷酸含量（ATP、ADP、AMP）维持在接近静息水平。在较高的抽搐率（72-240抽搐/分钟），总腺嘌呤核苷酸含量下降40%，反映了专门的ATP在存在足够的磷酸肌酸商店的下降。在所有收缩率下，乳酸与丙酮酸的比率在11-15的范围内反映了充分的氧合。
An in vitro rat muscle preparation is described that can contract at rates of 12-240 twitches/min. Maximum dF/dt paralleled maximum twitch tension, their ratio being constant at approximately 8 ms for contraction rates of 12-120 twitches/min. Time to peak tension was 8-13 ms, time to peak dF/dt 5-8 ms, and half-relaxation time 4 ms. These parameters were unaffected by rate of contraction or duration of isometric work. Differential ATPase staining demonstrated that 60-65% of the fibers were fast-twitch white, 20% fast-twitch red, and 15% slow-twitch red. The preponderance of fast-twitch fibers correlated with the observed mechanical performance of the muscle. Muscles contracting for 60 min at rates up to 48 twitches/min maintained total adenine nucleotide content (ATP, ADP, AMP) at near resting levels. At higher twitch rates (72-240 twitches/min), total adenine nucleotide content decreased 40%, reflecting exclusively a fall in ATP in the presence of adequate phosphocreatine stores. Adequate oxygenation was reflected by lactate-to-pyruvate ratios in the range of 11-15 at all rates of contraction.