Protective effects of lactic acid on force production in rat skeletal muscle
Protective effects of lactic acid on force production in rat skeletal muscle
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DOI：
10.1111/j.1469-7793.2001.t01-1-00161.x
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发表时间：
2001-10-01
影响因子：
5.5
通讯作者：
Overgaard, K
中科院分区：
文献类型：
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作者：
Nielsen, OB;de Paoli, F;Overgaard, K
1. 在剧烈运动中，乳酸的积累导致肌肉ph的降低。此外，运动导致肌肉K+的损失，导致细胞外K+浓度的增加（[K+](o)）。单独来看，pH的降低和[K+](o)的增加都被认为是导致肌肉疲劳的原因。为了研究这些变化对肌肉功能的综合影响，将离体大鼠比目鱼肌在[K+](o)为11 mM的条件下孵育，使破伤风力降低75%。然而，随后添加20毫米乳酸导致几乎完全的力恢复。如果通过添加丙酸或增加CO2张力来降低pH值，则观察到类似的回收率。从复合动作电位评估，力的恢复与肌肉兴奋性的恢复有关。相比之下，酸化对膜电位或Ca2+处理肌肉没有影响。结果表明，酸化可以抵消[K+](o)升高对肌肉兴奋性和力的抑制作用。由于剧烈运动与[K+](o)的增加有关，这表明，与酸中毒通常被认为是肌肉疲劳的原因相反，酸中毒可以预防疲劳。此外，这表明[K+](o)的升高对疲劳的重要性不如先前研究中孤立肌肉所表明的那样重要。
1. During strenuous exercise lactic acid accumulates producing a reduction in muscle pH. In addition, exercise causes a loss of muscle K+ leading to an increased concentration of extracellular K+ ([K+](o)). Individually, reduced pH and increased [K+](o) have both been suggested to contribute to muscle fatigue.2. To study the combined effect of these changes on muscle function, isolated rat soleus muscles were incubated at a [K+](o) of 11 mM, which reduced tetanic force by 75%. Subsequent addition of 20 mm lactic acid led, however, to an almost, complete force recovery. A similar recovery was observed if pH was reduced by adding propionic acid or increasing the CO2, tension.3. The recovery of force was associated with a recovery of muscle excitability as assessed from compound action potentials. In contrast, acidification had no effect on the membrane potential or the Ca2+ handling of the muscles.4. It is concluded that acidification counteracts the depressing effects of elevated [K+](o) on muscle excitability and force. Since intense exercise is associated with increased [K+](o) this indicates that, in contrast to the often suggested role for acidosis as a cause of muscle fatigue, acidosis may protect against fatigue. Moreover, it suggests that elevated [K+](o) is of less importance for fatigue than indicated by previous studies oil isolated muscles.