Responses of dorsal spinal cord blood flow to noxious mechanical stimulation of the skin in anesthetized rats.
In urethane-anesthetized, artificially ventilated rats, alterations in dorsal spinal cord blood flow (SCBF) at the L4-6 level were measured with laser Doppler flowmetry in response to noxious mechanical cutaneous stimulation (pinching) of either a forepaw or a hindpaw. The stimulation was delivered ipsilaterally or contralaterally to the site of blood flow measurement. Pinching of the forepaw or the hindpaw on either side increased mean arterial pressure (MAP) to the same degree. However, the SCBF response to pinching of the ipsilateral hindpaw was significantly greater than that to other stimulations. These responses were not influenced by denervation of the baroreceptors. The responses of SCBF to pinching of the ipsilateral hindpaw persisted both after treatment with phenoxybenzamine and after spinalization at the C1-2 level, whereas the responses to pinching at other sites disappeared. The responses of MAP to stimulation at all four sites became negligible after treatment with phenoxybenzamine and after spinalization at the C1-2 level. These results indicate that noxious mechanical stimulation of the skin produces increases in SCBF via two mechanisms: one is via an elevation of systemic arterial pressure; the other is via a localized spinal mechanism evoked by ipsilateral, segmental inputs.
Toda
Hiroko
H
Center for Medical Science, International University of Health and Welfare, Otawara, Tochigi, 324-8501 Japan.
Maruyama
Hitoshi
H
Budgell
Brian
B
Kurosawa
Mieko
M
D000316:Adrenergic alpha-Agonists / Q000008:administration & dosage; D000317:Adrenergic alpha-Antagonists / Q000008:administration & dosage; D000768:Anesthesia, General; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002572:Cervical Plexus / Q000601:surgery; D003714:Denervation; D007275:Injections, Intravenous; D017078:Laser-Doppler Flowmetry; D008161:Lumbosacral Region; D008297:Male; D010146:Pain / Q000503:physiopathology*; D010643:Phenoxybenzamine / Q000008:administration & dosage; D010656:Phenylephrine / Q000008:administration & dosage; D010812:Physical Stimulation; D011311:Pressoreceptors / Q000503:physiopathology; D051381:Rats; D017208:Rats, Wistar; D012039:Regional Blood Flow; D012867:Skin / Q000294:innervation*; D013116:Spinal Cord / Q000098:blood supply*
D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D010643:Phenoxybenzamine; D010656:Phenylephrine