title: Orthostatic effects of midodrine versus L-NAME on cerebral blood flow and the renin-angiotensin-aldosterone system in tetraplegia.
abstract: OBJECTIVE
  To compare responses to head-up tilt (HUT) in individuals with chronic tetraplegia after midodrine hydrochloride (10 mg) versus nitro-L-arginine methyl ester (L-NAME, 1 mg/kg) administration.
  
  
  METHODS
  Prospective comparative drug trial.
  
  
  METHODS
  Veterans Affairs medical center.
  
  
  METHODS
  Participants (N=7) were studied during 3 laboratory visits: no drug, midodrine (administered orally 30 min before HUT), and L-NAME (infused over a 60-min period).
  
  
  METHODS
  Anti-hypotensive agents, midodrine, and L-NAME.
  
  
  METHODS
  Mean arterial pressure (MAP), cerebral blood flow (CBF), and markers of the renin-angiotensin-aldosterone system (RAAS, plasma renin and serum aldosterone) were measured in the supine position at baseline (BL) and during a 45° HUT maneuver. Data were compared between BL and the average of 3 assessments collected during HUT.
  
  
  RESULTS
  Orthostatic MAP and CBF were increased with the midodrine and L-NAME groups compared with the no drug trial and the relationship between the change in MAP and CBF was significant (r=0.770; P<0.001). Both L-NAME and midodrine appeared to suppress the post-HUT RAAS response compared with no drug.
  
  
  CONCLUSIONS
  Increasing orthostatic blood pressure with L-NAME or midodrine appears to increase CBF and suppress the RAAS during HUT in persons with tetraplegia, although more data are needed to confirm these preliminary findings.
authors.affiliation: Center of Excellence, James J. Peters Veterans Affairs Medical Center, Bronx, NY 10468, USA. jm.wecht@va.gov
authors.forename: Jill M
authors.initials: JM
authors.lastname: Wecht
authors.forename: Miroslav
authors.initials: M
authors.lastname: Radulovic
authors.forename: Dwindally
authors.initials: D
authors.lastname: Rosado-Rivera
authors.forename: Run-Lin
authors.initials: RL
authors.lastname: Zhang
authors.forename: Michael F
authors.initials: MF
authors.lastname: LaFountaine
authors.forename: William A
authors.initials: WA
authors.lastname: Bauman
mesh_terms: D000328:Adult; D002560:Cerebrovascular Circulation / Q000187:drug effects*; D004244:Dizziness / Q000139:chemically induced*; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D008879:Midodrine / Q000494:pharmacology*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology*; D026741:Physical Therapy Modalities; D011446:Prospective Studies; D011782:Quadriplegia / Q000188:drug therapy; D012084:Renin-Angiotensin System / Q000187:drug effects*; D014481:United States; D014493:United States Department of Veterans Affairs; D014662:Vasoconstrictor Agents / Q000494:pharmacology*
chemical_list: D014662:Vasoconstrictor Agents; D008879:Midodrine; D019331:NG-Nitroarginine Methyl Ester