Cutaneous vasodilation during dorsal column stimulation is mediated
by dorsal roots and cgrp.
Croom, John E., Robert D. Foreman, Margaret J. Chandler, and Kirk W.
Barron.
Department of Physiology, University of Oklahoma Health Sciences
Center, P.O. Box 26901, Oklahoma City, Oklahoma 73109
APStracts 3:0417H, 1996.
Dorsal column stimulation (DCS) is used clinically to provide pain
relief from peripheral vascular disease and has the benefit of
increasing cutaneous blood flow to the affected lower extremities.
The purpose of this study was to examine the role of dorsal roots,
calcitonin gene-related peptide (CGRP), and substance P in the
cutaneous vasodilation induced by DCS. Male rats were anesthetized
with pentobarbital (60 mg/kg, i.p.). A unipolar ball electrode was
placed unilaterally on the spinal cord at the L1-L2 spinal segment.
Blood flow was recorded in each hindpaw foot pad with laser Doppler
flowmeters. Blood flow responses were assessed during 1 min of DCS
(either 0.2 mA (subdural) or 0.6 mA (epidural) at 50 Hz, 0.2 msec
pulse duration). Dorsal rhizotomy of L3-L5 (n=5) abolished the
cutaneous vasodilation to subdural DCS whereas removal of T10-T12
(n=5) and T13-L2 dorsal roots (n=5) did not attenuate the DCS-induced
vasodilation. The CGRP antagonist, CGRP(8-37) (2.6 mg/kg, i.v. n=7),
eliminated the epidural DCS-induced vasodilation whereas the
substance P receptor antagonist, CP-96,345 (1 mg/kg, i.v. n=6), had
no effect. In summary, L3-L5 dorsal roots and CGRP are essential for
the DCS-induced vasodilation. We propose that DCS antidromically
activates afferent fibers in the dorsal roots that causes peripheral
release of CGRP producing cutaneous vasodilation.
Received 27 June 1996; accepted in final form 6 September 1996.
APS Manuscript Number H571-6.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 5 November 1996