title: Passive Hind-Limb Cycling Reduces the Severity of Autonomic Dysreflexia After Experimental Spinal Cord Injury.
abstract: BACKGROUND
  Spinal cord injury (SCI) induces alterations in cardio-autonomic control of which autonomic dysreflexia (AD), a condition characterized by life-threatening hypertension, is arguably the most insidious. Passive hind-limb cycling represents a low-cost therapeutic intervention with demonstrable cardiovascular, sensory, and motor benefits.
  
  
  OBJECTIVE
  To investigate the effect of passive hind-limb cycling on AD in rodents with T3 SCI.
  
  
  METHODS
  Forty-five male Wistar rats were evenly assigned to either uninjured control (CON), SCI, or SCI plus hind-limb cycling exercise (SCI-EX). At the end of the experimental period (day 32), rats were randomly assigned to stream 1 (n = 24) or stream 2 (n = 21). Stream 1 rats were assessed for AD severity (pressor response to colorectal distension) and were then perfused for tissue dissection and immunohistochemistry. Stream 2 rats underwent excision of the superior mesenteric artery for in vitro myography assessments.
  
  
  RESULTS
  From 2 weeks post-SCI onwards, SCI-EX rats exhibited a significant reduction in the pressor response to colorectal distension versus SCI (P< .001). Reduced AD severity in SCI-EX rats was accompanied by a prevention of the SCI-induced increase in density of CGRP(+)afferents in the dorsal horn (P= .001). Conversely, both SCI and SCI-EX rats exhibited a similar degree of mesenteric endothelial dysfunction and α-adrenoceptor hypersensitivity versus CON.
  
  
  CONCLUSIONS
  Passive hind-limb cycling reduces the severity of AD in SCI, and is correlated with changes in primary afferent morphology, but has limited effects on the peripheral vasculature.
authors.affiliation: University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Christopher R
authors.initials: CR
authors.lastname: West
authors.affiliation: University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Crawford
authors.affiliation: University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Ismail
authors.initials: I
authors.lastname: Laher
authors.affiliation: University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Matt S
authors.initials: MS
authors.lastname: Ramer
authors.affiliation: University of British Columbia, Vancouver, British Columbia, Canada GF Strong Rehabilitation Centre, Vancouver Health Authority, British Columbia, Canada krassioukov@icord.org.
authors.forename: Andrei V
authors.initials: AV
authors.lastname: Krassioukov
mesh_terms: D000818:Animals; D020211:Autonomic Dysreflexia / Q000209:etiology / Q000628:therapy*; D004195:Disease Models, Animal; D006614:Hindlimb; D008297:Male; D015915:Motion Therapy, Continuous Passive / Q000379:methods*; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D012720:Severity of Illness Index; D013119:Spinal Cord Injuries / Q000150:complications / Q000628:therapy*
keywords: autonomic function; cardiovascular system; exercise; hypertension; vascular function