INITIAL FALL IN SKELETAL-MUSCLE FORCE DEVELOPMENT DURING ISCHEMIA IS RELATED TO OXYGEN AVAILABILITY
INITIAL FALL IN SKELETAL-MUSCLE FORCE DEVELOPMENT DURING ISCHEMIA IS RELATED TO OXYGEN AVAILABILITY
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DOI：
10.1152/jappl.1994.77.5.2380
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发表时间：
1994-11-01
影响因子：
3.3
通讯作者：
KURDAK, SS
中科院分区：
文献类型：
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作者：
HOGAN, MC;RICHARDSON, RS;KURDAK, SS
我们研究了以下假设：当血流停止时，工作肌肉中发生的力量发展的最初下降（前1-2分钟）是由O-2可用性引起的，而不是与血流相关的另一个因素。通过停止血流[缺血（I）]或在动脉O-2含量较低的情况下维持血流[低氧血症（H）]，减少向工作肌肉的O-2输送（肌肉血流量×动脉O-2含量），对此进行了测试。如果在这两种减少O-2输送的方法之间，力发展的初始下降相似，则表明O-2可用性是共同途径。以类似于最大O-2摄取的60-70%刺激离体狗腓肠肌（每2秒1次等长强直收缩），直到达到肌肉血流量和产生的力的稳态条件（类似于3分钟）。然后在工作肌肉上依次施加两种条件：I，通过关闭控制肌肉的动脉灌注的泵并夹紧静脉流出来诱导，和H，通过在稳态血流水平下用脱氧血（在测试之前收集，同时动物呼吸N-2）灌注肌肉来诱导。在17个匹配的条件下的H和I（类似于40秒的每种条件）的力生产下降率进行了比较，在6个肌肉测试。在H期间灌注肌肉的血液具有动脉Po-2 = 8 +/- 1（SE）Torr、动脉Pco（2）= 37 +/- 1 Torr和动脉pH = 7.39 +/- 0.03。在H（0.66 +/- 0.10 g力.g质量（-1）.s（-1））和I（0.79 +/- 0.15 g力.g质量（-1）.s（-1））的17个匹配条件之间，发展力的下降率没有显著差异（P = 0.46）。这些研究结果表明，最初的下降发达的力量在工作骨骼肌发生缺血是有关的O-2的可用性。
We examined the hypothesis that the initial decline (first 1-2 min) in force development that occurs in working muscle when blood flow is halted is caused by O-2 availability and not another factor related to blood flow. This was tested by reducing O-2 delivery (muscle blood flow X arterial O-2 content) to working muscle by either stopping blood flow [ischemia (I)] or maintaining blood flow with low arterial O-2 content [hypoxemia (H)]. If initial decline in force development were similar between these two methods of reducing O-2 delivery, it would suggest O-2 availability as the common pathway. Isolated dog gastrocnemius muscle was stimulated at similar to 60-70% of maximal O-2, uptake (1 isometric tetanic contraction every 2 s) until steady-state conditions of muscle blood flow and developed force were attained (similar to 3 min). Two conditions were then sequentially imposed on the working muscle: I, induced by shutting off pump controlling arterial perfusion of the muscle and clamping venous outflow, and H, induced by perfusing the muscle with deoxygenated blood (collected before testing while animal breathed N-2) at steady-state blood flow level. Rates of the fall in force production in 17 matched conditions of H and I (similar to 40 s for each condition) were compared in 6 muscles tested. The blood perfusing the muscle during H had arterial Po-2 = 8 +/- 1 (SE) Torr, arterial Pco(2) = 37 +/- 1 Torr, and arterial pH = 7.39 +/- 0.03. The rate of decline in developed force was not significantly different (P = 0.46) between the 17 matched conditions of H (0.66 +/- 0.10 g force.g mass(-1).s(-1)) and I (0.79 +/- 0.15 g force.g mass(-1).s(-1)). These findings suggest that the initial fall in developed force in working skeletal muscle that occurs with ischemia is related to O-2 availability.