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首页> 外文期刊>American Journal of Physiology >Time course of vasodilation at the onset of repetitive skeletal muscle contractions.
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Time course of vasodilation at the onset of repetitive skeletal muscle contractions.

机译：重复性骨骼肌收缩发作时血管舒张的时间过程。

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摘要

To characterize the vasodilatory response in the transition from a single skeletal contraction to a series of contractions, we measured the response of hamster cremaster muscle arterioles associated with four to five skeletal muscle fibers stimulated to contract for one, two, three, or four contractions (250-ms train duration) at 4-s intervals [15 contractions per minute (CPM)] for up to 12 s, at stimulus frequencies of 4, 10, 20, 30, 40, 60, and 80 Hz. To investigate the contribution of contraction frequency, we stimulated muscle fiber bundles at 30 or 60 CPM for 12 s at stimulus frequencies of 4, 20, and 60 Hz. Arteriolar diameters at the site of overlap with the stimulated muscle fibers were measured before and after each contraction. At 15 CPM at 4, 20, and 60 Hz, we observed a peak change in diameter following the first contraction of 1.1 +/- 0.1, 1.6 +/- 0.2, and 2.1 +/- 0.2 mum that almost doubled in response to the second contraction (2.0 +/- 0.1, 3.0 +/- 0.1, and 3.8 +/- 0.1 mum, respectively), but there was no further dilation following the third or fourth contraction. A similar response occurred at all stimulus and contraction frequencies tested. At 30 and 60 CPM at 60 Hz, the plateau after two contractions was followed by a further increase in diameter to a second plateau at 7-8 s. Therefore, the vasodilatory response in the transition from single to multiple contractions had components that were stimulation parameter dependent and independent and showed a plateauing behavior indicative of rapid changes in either the nature and/or concentration of vasodilators released or changes in vascular reactivity.
机译：为了表征从单一骨骼收缩到一系列收缩的过渡过程中的血管舒张反应，我们测量了与刺激四到五根骨骼肌纤维收缩一，二，三或四次收缩的仓鼠cremaster肌肉小动脉的反应（以4s，10、20、30、40、60和80 Hz的刺激频率，以4 s间隔[每分钟15次收缩（CPM）]持续12 s的250毫秒训练持续时间。为了研究收缩频率的影响，我们以4、20和60 Hz的刺激频率在30或60 CPM下刺激了12 s的肌纤维束。在每次收缩之前和之后，测量与刺激的肌肉纤维重叠的部位的小动脉直径。在15 CPM在4、20和60 Hz时，我们观察到第一次收缩1.1 +/- 0.1、1.6 +/- 0.2和2.1 +/- 0.2毫米后，直径出现了峰值变化，响应于第二次收缩（分别为2.0 +/- 0.1、3.0 +/- 0.1和3.8 +/- 0.1毫米），但在第三或第四次收缩后没有进一步扩张。在所有测试的刺激和收缩频率下都发生了类似的反应。在60 Hz的30 CPM和60 CPM下，两次收缩后的平稳期之后，直径进一步增加至7-8 s的第二平稳期。因此，从单次收缩到多次收缩的血管舒张反应具有依赖于刺激参数且独立的成分，并且表现出平稳的行为，表明释放的血管舒张剂的性质和/或浓度快速变化或血管反应性变化。

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