The control of blood flow through human forearm muscles following brief isometric contractions.
The control of blood flow through human forearm muscles following brief isometric contractions.
复制标题
短暂等长收缩后对流经人体前臂肌肉的血流的控制。
DOI：
10.1113/jphysiol.1979.sp012711
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发表时间：
1979
期刊：
影响因子：
--
通讯作者：
C. Williams
中科院分区：
文献类型：
--
作者：
A. R. Lind;C. Williams
1.在单次短暂等长握柄收缩后2秒测量通过前臂的血流量。这些收缩的张力和持续时间从最大自主收缩（m.v.c.）的10%至100%变化。和2 - 12秒。2.当张力达到约60% m.v.c.时，血流量呈线性增加。但是张力进一步增加，直到100% m.v.c.，不会引起比60% m.v.c.时更高的血流量张力和由此产生的血流量之间的关系在所有收缩持续时间（从2秒到12秒）都保持不变。在给定的张力下，收缩后立即（2秒）的血流量随着收缩的持续时间线性增加，从2秒增加到12秒。只有在60% m.v.c.张力下最长收缩（12秒）时才接近最大运动血流量或更高. 3.跨血管跨壁压的短暂变化（2--5秒）不会导致血流发生显着变化，无论是在静息前臂中还是在血管通过短暂的等长收缩扩张时。当张力被施加或释放时，无论是快速还是逐渐（“斜坡”收缩），动脉血管上的拉伸变化率与所产生的血流之间没有相关性。然而，力-时间积分（收缩持续时间x峰值张力）与血流之间存在直接关系。所有这些结果表明，由短暂的等长收缩引起的前臂血流变化不是肌源性反射的结果，而是代谢诱导的。4.在60% m.v.c.下连续收缩4秒诱导的血流量为21.2 +/-1.6 ml.min-1.100 ml. -1，收缩之间的休息间隔为8秒。血流量保持恒定在这个亚最大水平，即使肌肉疲劳诱导，当有一个伴随的血压大幅增加。5.对侧手臂的等长肌肉活动导致疲劳，与平均血压的大幅增加相关，但并没有改变“测试”手臂中由短暂等长收缩引起的血管舒张水平。这表明，血管舒张反应间歇性等长收缩的结果是代谢性血管舒张的远端段和持续的交感神经血管收缩的近端段的前臂血管床。
1. The blood flow through the forearm was measured 2 sec after single, brief isometric hand‐grip contractions. The tension and duration of those contractions varied from 10 to 100% of the maximal voluntary contraction (m.v.c.) and from 2 to 12 sec, respectively. 2. The blood flow increased linearly with tension up to about 60% m.v.c. but further increases in tension, up to 100% m.v.c., did not elicit higher blood flows than were found at 60% m.v.c. The same relationship between tension and the resultant blood flow held for all durations of contractions, from 2 to 12 sec. The blood flow immediately after (2 sec) contractions at a given tension increased linearly with the duration of the contraction, from 2 to 12 sec. Maximal exercise blood flow was approached only in response to the longest contractions (12 sec) at tensions of 60% m.v.c. or higher. 3. Brief alterations (2‐‐5 sec) of transmural pressure across blood vessels did not result in a significant change of blood flow, either in the resting forearm or when the vessels were dilated by brief, isometric contractions. When the tension was applied or released either rapidly or gradually ('ramp' contractions) there was no correlation between the rate of change of stretch on arterial vessels and the resultant blood flow. However, there was a direct relationship between a force‐‐time integral (duration of contraction x peak tension) and blood flow. All these results make it clear that changes in blood flow in the forearm elicited by brief isometric contractions are not the result of a myogenic reflex but are metabolically induced. 4. Successive contractions exerted at 60% m.v.c. for 4 sec induced a blood flow of 21.2 +/‐ 1.6 ml.min‐1.100 ml.‐1 when a rest interval of 8 sec was allowed between the contractions. Blood flows remained constant at this submaximal level, even when muscular fatigue was induced, and when there was an accompanying large increase in blood pressure. 5. Isometric muscular activity by the contralateral arm which resulted in fatigue, associated with a large increase in mean blood pressure, did not alter the level of vasodilation that was induced by brief, isometric contractions in the 'test' arm. 6. It is suggested that the vasodilatation in response to intermittent isometric contractions is the result of metabolic vasodilatation of distal segments and continued sympathetic vasoconstriction of the proximal segments of the forearm vascular bed.