Human neuromuscular fatigue is associated with altered Na+-K+-ATPase activity following isometric exercise
Human neuromuscular fatigue is associated with altered Na+-K+-ATPase activity following isometric exercise
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DOI：
10.1152/japplphysiol.00668.2001
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发表时间：
2002-04-01
影响因子：
3.3
通讯作者：
Roy, BD
中科院分区：
文献类型：
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作者：
Fowles, JR;Green, HJ;Roy, BD
本研究旨在探讨等长运动后Na +-K +-ATP酶活性降低与神经肌肉疲劳相关的假说。在对照组（Con）和运动组（Ex）中，对14名志愿者[年龄，23.4 +/-0.7（SE）岁]在等长收缩之前和之后立即（PST0）、之后1小时（PST1）和之后4小时（PST4）测量力量和肌电图，以0.5的占空比（收缩5秒，休息5秒），以60%的最大随意收缩进行单腿伸展运动30分钟。在Con组中，在运动前以及在Con组（PST0）和Ex组（PST0、PST1、PST4）中，从股外侧肌获取组织，用于测量Na +-K +-ATP酶活性，如通过3-O-甲基荧光素磷酸酶（3-O-MFPase）测定法所确定的。自主（最大自主收缩）和诱发（10、20、50、100 Hz）力在PST 0时减少30 - 55%（P <0.05），到PST 4时未恢复。PST0-Ex组的肌肉动作电位（M波）振幅和面积（在股内侧肌中测量）以及3-O-MFPase活性分别比PST0-Con组低37%、25%和38%（P <0.05）。M-wave面积在PST1-Ex组也小于PST1-Con组（P <0.05）。3-O-MFPase活性的变化与M波面积的变化在所有时间点相关（r = 0.38，P <0.05，n = 45）。这些结果表明，Na +-K +-ATP酶活性降低持续等长运动在人类从一个匹配的Con腿，这种减少Na +-K +-ATP酶活性与兴奋性的损失，如M波改变所示。
The purpose of this study was to investigate the hypothesis that reductions in Na+-K+-ATPase activity are associated with neuromuscular fatigue following isometric exercise. In control (Con) and exercised (Ex) legs, force and electromyogram were measured in 14 volunteers [age, 23.4 +/- 0.7 (SE) yr] before and immediately after (PST0), 1 h after (PST1), and 4 h after (PST4) isometric, single-leg extension exercise at similar to60% of maximal voluntary contraction for 30 min using a 0.5 duty cycle (5-s contraction, 5-s rest). Tissue was obtained from vastus lateralis muscle before exercise in Con and after exercise in both the Con (PST0) and Ex legs (PST0, PST1, PST4), for the measurements of Na+-K+-ATPase activity, as determined by the 3-O-methylfluorescein phosphatase (3-O-MFPase) assay. Voluntary (maximal voluntary contraction) and elicited (10, 20, 50, 100 Hz) force was reduced 30-55% (P < 0.05) at PST0 and did not recover by PST4. Muscle action potential (M-wave) amplitude and area (measured in the vastus medialis) and 3-O-MFPase activity at PST0-Ex were less than that at PST0-Con (P < 0.05) by 37, 25, and 38%, respectively. M-wave area at PST1-Ex was also less than that at PST1-Con (P < 0.05). Changes in 3-O-MFPase activity correlated to changes in M-wave area across all time points (r = 0.38, P < 0.05, n = 45). These results demonstrate that Na+-K+-ATPase activity is reduced by sustained isometric exercise in humans from that in a matched Con leg and that this reduction in Na+-K+-ATPase activity is associated with loss of excitability as indicated by M-wave alterations.