含有香草酸受体-1（VR-1）的感觉纤维介导脊髓刺激诱导的血管舒张。
Sensory fibers containing vanilloid receptor-1 (VR-1) mediate spinal cord stimulation-induced vasodilation.
作者信息
Wu Mingyuan, Komori Naoka, Qin Chao, Farber Jay P, Linderoth Bengt, Foreman Robert D
机构信息
Department of Physiology, University of Oklahoma Health Sciences Center, PO BOX 26901, Oklahoma City, OK 73190, USA, and Karolinska University Hospital, Stockholm, Sweden.
出版信息
Brain Res. 2006 Aug 30;1107(1):177-84. doi: 10.1016/j.brainres.2006.05.087. Epub 2006 Jul 11.
BACKGROUND AND AIMS
Spinal cord stimulation (SCS) is used to improve peripheral blood flow in selected populations of patients with ischemia of the extremities. Previous studies show that antidromic activation of sensory fibers is an important mechanism that contributes to SCS-induced vasodilation. However, the characteristics of sensory fibers involved in vasodilation are not fully known. This study investigated the contribution of vanilloid receptor type 1 (VR-1) containing fibers to SCS-induced vasodilation.
METHODS
A unipolar ball electrode was placed on the left dorsal column at the lumbar 2-3 spinal cord segments (L2-L3) in sodium pentobarbital anesthetized, paralyzed and ventilated rats. Cutaneous blood flows from both ipsilateral (left) and contralateral (right) hind foot pads were recorded with laser Doppler flow perfusion monitors. SCS (50 Hz; 0.2 ms) was applied through the ball electrode at 30%, 60%, 90% and 300% of motor threshold (MT). Resiniferatoxin (RTX), an ultra potent analog of capsaicin and VR-1 receptor agonist, was used to suppress the activities of VR-1 containing sensory fibers.
RESULTS
SCS at 30%, 60%, 90% and also at 300% of MT significantly increased cutaneous blood flow in the ipsilateral foot pad compared to that in the contralateral side. RTX (2 microg/kg, i.v.) significantly attenuated SCS-induced vasodilation of the ipsilateral side (P<0.05, n=7) compared with responses prior to RTX administration. A pledget of cotton soaked with RTX (2 microg/ml) placed on L2-L3 spinal cord significantly decreased SCS-induced vasodilation of the ipsilateral side at 30%, 60%, 90% and 300% of MT (P<0.05, n=7) compared with responses prior to RTX administration. Additionally, topical application of a pledget of cotton soaked with RTX (2 microg/ml) on the sciatic nerve at the middle level of the thigh or on the tibial nerve at the lower level of the lower hindlimb also decreased SCS-induced vasodilation (n=5).
CONCLUSION
SCS-induced vasodilation is predominantly mediated via VR-1 containing sensory fibers.
背景与目的
脊髓刺激（SCS）用于改善特定肢体缺血患者群体的外周血流。先前的研究表明，感觉纤维的逆向激活是促成SCS诱导血管舒张的重要机制。然而，参与血管舒张的感觉纤维的特征尚不完全清楚。本研究调查了含1型香草酸受体（VR-1）的纤维对SCS诱导血管舒张的作用。
方法
在戊巴比妥钠麻醉、麻痹并通气的大鼠中，将单极球形电极置于腰2-3脊髓节段（L2-L3）的左侧背柱上。用激光多普勒血流灌注监测仪记录同侧（左侧）和对侧（右侧）后足垫的皮肤血流。通过球形电极以运动阈值（MT）的30%、60%、90%和300%施加SCS（50Hz；0.2ms）。使用辣椒素超效类似物和VR-1受体激动剂树脂毒素（RTX）来抑制含VR-1感觉纤维的活性。
结果
与对侧相比，MT的30%、60%、90%以及300%的SCS均显著增加同侧足垫的皮肤血流。与RTX给药前的反应相比，RTX（2μg/kg，静脉注射）显著减弱了SCS诱导的同侧血管舒张（P<0.05，n=7）。将浸有RTX（2μg/ml）的棉球置于L2-L3脊髓上，与RTX给药前的反应相比，在MT的30%、60%、90%和300%时，显著降低了SCS诱导的同侧血管舒张（P<0.05，n=7）。此外，在大腿中部的坐骨神经或后下肢下部的胫神经上局部应用浸有RTX（2μg/ml）的棉球也可降低SCS诱导的血管舒张（n=5）。
结论
SCS诱导的血管舒张主要通过含VR-1的感觉纤维介导。
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