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.

DESIGN:

Prospective comparative drug trial.

SETTING:

Veterans Affairs medical center.

PARTICIPANTS:

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).

INTERVENTIONS:

Anti-hypotensive agents, midodrine, and L-NAME.

MAIN OUTCOME MEASURES:

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: Jill M Wecht, Miroslav Radulovic, Dwindally Rosado-Rivera, Run-Lin Zhang, Michael F LaFountaine, William A Bauman
• Journal: Archives of physical medicine and rehabilitation (Arch Phys Med Rehabil) Vol. 92 Issue 11 Pg. 1789-95 (Nov 2011) ISSN: 1532-821X [Electronic] United States
• PMID: 21762873 (Publication Type: Comparative Study, Journal Article, Research Support, U.S. Gov't, Non-P.H.S.)
• Copyright: Copyright © 2011 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Chemical References

• Vasoconstrictor Agents
• Midodrine
• NG-Nitroarginine Methyl Ester

Topics

• Adult
• Cerebrovascular Circulation (drug effects)
• Dizziness (chemically induced)
• Female
• Hemodynamics (drug effects)
• Humans
• Male
• Middle Aged
• Midodrine (pharmacology)
• NG-Nitroarginine Methyl Ester (pharmacology)
• Physical Therapy Modalities
• Prospective Studies
• Quadriplegia (drug therapy)
• Renin-Angiotensin System (drug effects)
• United States
• United States Department of Veterans Affairs
• Vasoconstrictor Agents (pharmacology)