Effect of varied extracellular PO2 on muscle performance in Xenopus single skeletal muscle fibers.
Effect of varied extracellular PO2 on muscle performance in Xenopus single skeletal muscle fibers.
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不同细胞外 PO2 对非洲爪蟾单骨骼肌纤维肌肉性能的影响。
DOI：
10.1152/jappl.1999.86.6.1812
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发表时间：
1999
期刊：
影响因子：
--
通讯作者：
Hogan,MC
中科院分区：
文献类型：
--
作者：
Stary,CM;Hogan,MC
本研究的目的是研究疲劳的发展，在孤立的，单一的骨骼肌纤维时，O2的可用性降低，但不考虑限制线粒体呼吸速率的水平。在非洲爪蟾（Xenopus laevis）的单个活肌纤维（n= 6）中测量强直力，同时以增加的收缩速率刺激（0.25、0.33、0.5和1 Hz），每个刺激频率持续2分钟。肌肉疲劳（确定为初始最大力的75%）在三次单独的工作回合期间进行测量（之间休息45分钟），灌注在分块顺序设计中在30 ± 1.9、76 ± 3.0或159 Torr的值之间切换。高、中和低治疗组之间的初始峰值张力无显著差异（分别为323 ± 22、298 ± 27和331 ± 24 kPa）。与76-（385 ± 62 s）或159-Torr（416 ± 65 s）治疗相比，30-Torr治疗（233 ± 39 s）期间达到疲劳的时间显著更快（P< 0.05）。在这些纤维内形成缺氧核心所需的计算临界细胞外压力为13 ± 1 Torr，表明30 Torr的细胞外压力不应限制线粒体呼吸的速率。在研究条件下，不搅拌层的大小（243 ± 64 μm）或细胞内O2扩散系数（0.45 ± 0.04 × 10− 5cm 2/s）不太可能形成缺氧核心。在最低的细胞外条件下，在生理上高的细胞内水平，较早开始疲劳，表明肌肉性能可能是O2依赖性的，即使线粒体呼吸不一定受到损害。
The purpose of this study was to examine the development of fatigue in isolated, single skeletal muscle fibers when O2availability was reduced but not to levels considered rate limiting to mitochondrial respiration. Tetanic force was measured in single living muscle fibers (n= 6) fromXenopus laeviswhile being stimulated at increasing contraction rates (0.25, 0.33, 0.5, and 1 Hz) in a sequential manner, with each stimulation frequency lasting 2 min. Muscle fatigue (determined as 75% of initial maximum force) was measured during three separate work bouts (with 45 min of rest between) as the perfusatewas switched between values of 30 ± 1.9, 76 ± 3.0, or 159 Torr in a blocked-order design. No significant differences were found in the initial peak tensions between the high-, intermediate-, and low-treatments (323 ± 22, 298 ± 27, and 331 ± 24 kPa, respectively). The time to fatigue was reached significantly sooner (P< 0.05) during the 30-Torr treatment (233 ± 39 s) compared with the 76- (385 ± 62 s) or 159-Torr (416 ± 65 s) treatments. The calculated critical extracellularnecessary to develop an anoxic core within these fibers was 13 ± 1 Torr, indicating that the extracellularof 30 Torr should not have been rate limiting to mitochondrial respiration. The magnitude of an unstirred layer (243 ± 64 μm) or an intracellular O2diffusion coefficient (0.45 ± 0.04 × 10−5cm2/s) necessary to develop an anoxic core under the conditions of the study was unlikely. The earlier initiation of fatigue during the lowest extracellularcondition, at physiologically high intracellularlevels, suggests that muscle performance may be O2dependent even when mitochondrial respiration is not necessarily compromised.
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影响因子：
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影响因子：
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DOI：
--
发表时间：
1965
期刊：
影响因子：
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作者：
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