1995 Fiscal Year Final Research Report Summary
Mechanism of neural regulation of the sciatic nerve blood flow
| Project/Area Number |
06680820
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
神経・脳内生理学
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| Research Institution | Tsukuba College of Technology |
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Principal Investigator |
SATO Yuko Tsukuba College of Technology, Lab.Physiol., Professor, 鍼灸学科, 教授 (10072985)
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| Co-Investigator(Kenkyū-buntansha) |
OHSAWA Hideo Tsukuba College of Technology, Lab.Physiol., Assistant, 鍼灸学科, 助手 (40223789)
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| Project Period (FY) |
1994 – 1995
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| Keywords | Nerve blood flow / Sciatic nerve / Laser Doppler flowmetry / Axon reflex / Acetylcholine / CGRP / Rat |
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| Research Abstract |
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
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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
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