Murrant C L, Sarelius I H
Department of Pharmacology and Physiology, University of Rochester, Rochester, New York 14642, USA.
Am J Physiol Heart Circ Physiol. 2000 Nov;279(5):H2285-94. doi: 10.1152/ajpheart.2000.279.5.H2285.
To investigate the relationship between skeletal muscle metabolism and arteriolar dilations in the region local to contracting muscle fibers as well as dilations at remote arteriolar regions upstream, we used a microelectrode on cremaster muscle of anesthetized hamsters to stimulate four to five muscle fibers lying approximately perpendicular to and overlapping a transverse arteriole. Before, during, and after muscle contraction, we measured the diameter of the arteriole at the site of muscle fiber overlap (local) and at a remote site approximately 1,000 microm upstream. Two minutes of 2-, 4-, or 8-Hz stimulation (5-10 V, 0.4-ms duration) produced a significant dilation locally (8.2 +/- 2.0-, 22.5 +/- 2.4-, and 30.9 +/- 2.1-microm increase, respectively) and at the remote site (4.2 +/- 0.8, 11.0 +/- 1.1, and 18.9 +/- 2.7 microm, respectively). Muscle contraction at 4 Hz initiated a remote dilation that was unaffected by 15-min micropipette application of either 2 microM tetrodotoxin, 0.07% halothane, or 40 microM 18-beta-glycyrrhetinic acid between the local and upstream site. Therefore, at the arteriolar level, muscle contraction initiates a robust remote dilation that does not appear to be transmitted via perivascular nerves or gap junctions.
为了研究收缩肌纤维局部区域的骨骼肌代谢与小动脉扩张之间的关系，以及上游远端小动脉区域的扩张情况，我们使用微电极刺激麻醉仓鼠提睾肌中大约垂直于一条横向小动脉并与其重叠的四到五条肌纤维。在肌肉收缩前、收缩期间和收缩后，我们测量了肌纤维重叠部位（局部）和上游约1000微米处远端部位的小动脉直径。2分钟的2赫兹、4赫兹或8赫兹刺激（5 - 10伏，0.4毫秒持续时间）分别在局部（分别增加8.2±2.0微米、22.5±2.4微米和30.9±2.1微米）和远端部位（分别增加4.2±0.8微米、11.0±1.1微米和18.9±2.7微米）产生了显著的扩张。4赫兹的肌肉收缩引发了远端扩张，在局部和上游部位之间微量注射2微摩尔河豚毒素、0.07%氟烷或40微摩尔18-β-甘草次酸15分钟对此无影响。因此，在小动脉水平，肌肉收缩引发了强烈的远端扩张，这种扩张似乎不是通过血管周围神经或缝隙连接传递的。
