Mechanisms of sustained cutaneous vasodilation induced by spinal cord stimulation.
This study was performed to investigate whether spinal cord stimulation (SCS) at intensities below motor threshold prolongs cutaneous vasodilation and whether sustained vasodilation by SCS is mediated through sympathetic inhibition and/or antidromic activation of sensory fibers. SCS was applied to the dorsal surface of the L2-L3 spinal cord of anesthesized rats with stimulus parameters used clinically (i.e., 50 Hz, 0.2 ms duration, and stimulus intensity at 30%, 60%, or 90% of motor threshold). Peripheral vasodilation induced by 5-min SCS was not attenuated by hexamethonium, an autonomic ganglion-blocking agent, but was abolished by dorsal rhizotomy. SCS at < or = 60% of motor threshold increased cutaneous blood flow to the level similar to that obtained at 90% of motor threshold, but the vasodilation did not last for 5 min. SCS-induced vasodilation at 90% of motor threshold persisted for the entire stimulation period up to 30 min, and the vasodilation was not attenuated by hexamethonium. It is concluded that sustained vasodilation, which is induced by SCS at only 90% of motor threshold, in this study was mediated via antidromic activation of sensory fibers.
Department of Physiology, University of Oklahoma Health Sciences Center, P.O. Box 26901, Oklahoma City, OK 73190, United States.
Satoshi
S
Tanaka
Naoka
N
Komori
Kirk W
KW
Barron
Margaret J
MJ
Chandler
Bengt
B
Linderoth
Robert D
RD
Foreman
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D004558:Electric Stimulation / Q000379:methods; D007839:Functional Laterality / Q000502:physiology; D006340:Heart Rate, Fetal / Q000187:drug effects / Q000502:physiology; D018738:Hexamethonium / Q000494:pharmacology; D008297:Male; D018733:Nicotinic Antagonists / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012039:Regional Blood Flow / Q000187:drug effects / Q000502:physiology; D019051:Rhizotomy / Q000379:methods; D012867:Skin / Q000098:blood supply*; D013116:Spinal Cord / Q000502:physiology* / Q000528:radiation effects; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects
D018733:Nicotinic Antagonists; D018738:Hexamethonium