Mechanism of neural regulation of the sciatic nerve blood flow

1. 应用激光多普勒血流仪观察了坐骨神经神经血流量（NBF）对第11胸椎段和第2骶椎段之间脊神经腹根或背根反复电刺激的反应。(1)刺激T11-L1腹侧神经根产生双相NBF反应，包括最初的增加和随后的减少。最初的增加是由于平均动脉压（MAP）的增加而导致的被动血管扩张，而随后的NBF下降是由于支配坐骨血管神经的交感神经的激活而导致的血管收缩。(2)刺激L6节段腹侧根使NBF增加，尽管MAP减少。静脉注射阿托品（一种毒蕈碱胆碱能受体拮抗剂）可消除NBF的增加。(3)刺激L3节段和S1节段之间的背根使NBF增加，但与MAP的变化无关。局部应用降钙素生成肽（CGRP）受体拮抗剂可消除NBF的增加。综上所述，坐骨神经的NBF受(1)从脊髓前根经T11-L1节段流出的交感血管收缩剂，(2)从脊髓前根经L6节段流出的副交感血管扩张剂，以及(3)含血管扩张剂经L3-S1节段进入脊髓后根的传入CGRP的调控。研究了肽能传入血管舒张纤维在血管神经血流调节中的生理相关性，特别是轴突反射。在腰骶传入神经和传出神经与脊髓分离的麻醉大鼠中，观察坐骨神经NBF对隐神经传入神经电刺激的反应。重复电刺激隐神经中央切端无髓鞘纤维可使刺激同侧坐骨神经NBF增加，与MAP的变化无关。局部应用CGRP受体拮抗剂可消除这种增加。综上所述，坐骨神经的NBF是由隐神经中含有血管扩张剂的无髓鞘传入CGRP通过轴突反射样机制调节的。少

1. The response of nerve blood flow (NBF) in the sciatic nerve to repetitive electrical stimulation of either the ventral or dorsal root of the spinal nerves between the llth thoracic and 2nd sacral spinal segments, was examined using laser Doppler flowmetry. (1) Stimulation of the T11-L1 ventral roots produced a biphasic NBF response comprised of an initial increase and a subsequent decrease. The initial increase was a passive vasodilation due to the increase in mean arterial pressure (MAP), while the following decrease in NBF resulted from active vasoconstriction of the vasa nervorum due to the activation of sympathetic nerves innervating the sciatic vasa nervorum. (2) Stimulation of the ventral root of the L6 segment produced an increase in NBF,even though MAP decreased. This increase in NBF was abolished by i. v. injection of atropine, a muscarinic cholinergic receptor antagonist. (3) Stimulation of the dorsal roots between the L3 and S1 segments produced an increase in NBF,indepen … More dent of changes in MAP.This increase in NBF was abolished by topical application of a calcitonin generelated peptide (CGRP) receptor antagonist. In conclusion, NBF in the sciatic nerve is regulated by (1) sympathetic vasoconstrictors exiting the ventral roots of the spinal cord via the T11-L1 segments, (2) parasympathetic vasodilators exiting the ventral roots of the spinal cord via the L6 segment and (3) afferent CGRP containing vasodilators entering the dorsal roots of the spinal cord via the L3-S1 segments.2. The physiological relevance of peptidergic afferent vasodilative fibers in the regulation of blood flow in the vasa nervorum, with special reference to the axon reflex, was examined. The response of NBF in the sciatic nerve to electrical stimulation of saphenous nerve afferents was examined in anesthetized rats whose lumbosacral afferents and efferents had been disconnected from the spinal cord. Repetitive electrical stimulation of unmyelinated fibers in the central cut end of the saphenous nerve produced an increase in NBF in the sciatic nerve ipsilateral to the stimulation, independent of changes in MAP.This increase was abolished by topical application of CGRP receptor antagonest. In conclusion, NBF in the sciatic nerve is regulated via an axon reflex-like mechanism by unmyelinated afferent CGRP containing vasodilators with collaterals in the saphenous nerve. Less