A test of the role of flow-dependent dilation in arteriolar responses to occlusion.
A test of the role of flow-dependent dilation in arteriolar responses to occlusion.
复制标题
测试流量依赖性扩张在小动脉对闭塞反应中的作用。
DOI：
10.1152/ajpheart.1997.272.2.h714
复制
发表时间：
1997
期刊：
影响因子：
--
通讯作者：
Duling,BR
中科院分区：
文献类型：
--
作者：
McGahren,ED;Dora,KA;Damon,DN;Duling,BR
据报道，在小动脉分叉处，其中一个分支小动脉的闭塞导致相对未闭塞的分支中的流量、剪切应力和血管舒张增加。在未闭塞的分支中的这种扩张反应，通常被称为“平行闭塞反应”，已经被引用作为流量依赖性扩张是微循环中小动脉直径的主要调节剂的证据。以前没有注意到，在这种操作过程中，通过供血小动脉的流量预计会减少，并且在逻辑上应该导致该血管收缩。我们测试了这种预测在体内通过测量红细胞（RBC）的速度和直径的变化，在微循环床的小动脉闭塞的三个制剂：仓鼠颊囊，仓鼠提睾肌，和大鼠提睾肌。在所有制剂中，在供血小动脉中观察到血管舒张，尽管通过该血管的流量和计算的壁切应力均降低。出乎意料的是，我们发现，扩张发生在未闭塞的分支小动脉，即使在这些情况下，红细胞的速度和剪切力没有增加，在未闭塞的分支小动脉。在去除闭塞后，所有值均恢复至基线水平。饲料和分支小动脉的扩张幅度在物种和组织之间变化，但饲料和分支小动脉在给定的准备总是以类似的方式相互响应。我们的结论是，从我们的实验，机制以外的流量依赖性扩张参与微循环中观察到的血管舒张过程中闭塞的小动脉分支。
At an arteriolar bifurcation, occlusion of one of the branch arterioles has been reported to result in an increase in flow, shear stress, and vasodilation in the opposite unoccluded branch. This dilator response in the unoccluded branch, often referred to as the "parallel occlusion response," has been cited as evidence that flow-dependent dilation is a primary regulator of arteriolar diameter in the microcirculation. It has not been previously noted that, during this maneuver, flow through the feed arteriole would be expected to decrease and logically should cause that vessel to constrict. We tested this prediction in vivo by measuring red blood cell (RBC) velocity and diameter changes in response to arteriolar occlusion in the microcirculatory beds of three preparations: the hamster cheek pouch, the hamster cremaster, and the rat cremaster. In all preparations, a vasodilation was observed in the feed arteriole, despite a decrease in both flow and calculated wall shear stress through this vessel. Unexpectedly, we found that dilation occurred in the unoccluded branch arterioles even in those cases in which RBC velocity and shear stress did not increase in the unoccluded branch arterioles. All values returned to the baseline level after the removal of occlusion. The magnitude of the dilation of the feed and branch arterioles varied between species and tissues, but feed and branch arterioles within a given preparation always responded in a similar way to each other. We conclude from our experiments that mechanisms other than flow-dependent dilation are involved in the vasodilation observed in the microcirculation during occlusion of an arteriolar branch.