Boegehold M A
Department of Physiology, West Virginia University School of Medicine, Morgantown 26506, USA.
Am J Physiol. 1996 Aug;271(2 Pt 2):H387-95. doi: 10.1152/ajpheart.1996.271.2.H387.
This study was designed to determine whether shear-dependent changes in venular nitric oxide (NO) production can influence nearby arteriolar tone and whether this mechanism contributes to functional arteriolar dilation in contracting muscle. In resting spinotrapezius muscle of anesthetized rats, occlusion of one branch of an arcade venular bifurcation with divergent flow caused flow and wall shear rate in the parallel branch to increase by an average of 99 and 72%, respectively. After 10-30 s, the paired arcade arteriole dilated by an average of 30%, with a correlation between the increase in venular shear rate and the magnitude of arteriolar dilation. During muscle contraction, arcade arterioles dilated by 73-97% and arcade venular shear rate increased by 48-83%. The NO synthase inhibitor NG-monomethyl-L-arginine greatly attenuated arteriolar dilation to increased venular shear rate in resting muscle but did not affect arteriolar dilation in contracting muscle. These findings suggest that a shear-dependent increase in venular NO release can dilate nearby arterioles, but this mechanism is not important for the sustained dilation of these arterioles during functional hyperemia.
本研究旨在确定小静脉一氧化氮（NO）生成中与剪切力相关的变化是否会影响附近小动脉的张力，以及该机制是否有助于收缩肌肉中小动脉的功能性扩张。在麻醉大鼠的静息斜方肌中，对具有不同血流的弓形静脉分叉的一个分支进行闭塞，导致平行分支中的血流和壁剪切率分别平均增加99%和72%。10 - 30秒后，配对的弓形小动脉平均扩张30%，小静脉剪切率的增加与小动脉扩张幅度之间存在相关性。在肌肉收缩期间，弓形小动脉扩张73 - 97%，弓形小静脉剪切率增加48 - 83%。NO合酶抑制剂NG - 单甲基 - L - 精氨酸极大地减弱了静息肌肉中小动脉对增加的小静脉剪切率的扩张反应，但不影响收缩肌肉中小动脉的扩张。这些发现表明，小静脉NO释放中与剪切力相关的增加可使附近小动脉扩张，但该机制对功能性充血期间这些小动脉的持续扩张并不重要。
