Effects of midodrine on exercise-induced hypotension and blood pressure recovery in autonomic failure.

Abstract

We tested the hypothesis that the oral alpha1-adrenergic agonist, midodrine, would limit the fall in arterial pressure observed during exercise in patients with pure autonomic failure (PAF). Fourteen subjects with PAF underwent a stand test, incremental supine cycling exercise (25, 50, and 75 W), and ischemic calf exercise, before (control) and 1 h after ingesting 10 mg midodrine. Heart rate (ECG), beat-to-beat blood pressure (MAP, arterial catheter), cardiac output (Q, open-circuit acetylene breathing), forearm blood flow (FBF, Doppler ultrasound), and calf blood flow (CBF, venous occlusion plethysmography) were measured. The fall in MAP after standing for 2 min was similar ( approximately 60 mmHg; P = 0.62). Supine MAP immediately before cycling was greater after midodrine (124 +/- 6 vs 117 +/- 6 mmHg; P < 0.03), but cycling caused a workload-dependent hypotension (P < 0.001), whereas increases in Q were modest but similar. Midodrine increased MAP and total peripheral resistance (TPR) during exercise (P < 0.04), but the exercise-induced fall in MAP and TPR were similar during control and midodrine (P = 0.27 and 0.14). FBF during cycling was not significantly reduced by midodrine (P > 0.2). By contrast, recovery of MAP after cycling was faster (P < 0.04) after midodrine ( approximately 25 mmHg higher after 5 min). Ischemic calf exercise evoked similar peak CBF in both trials, but midodrine reduced the hyperemic response over 5 min of recovery (P < 0.02). We conclude midodrine improves blood pressure and TPR during exercise and dramatically improves the recovery of MAP after exercise.

• Authors: William G Schrage, John H Eisenach, Frank A Dinenno, Shelly K Roberts, Christopher P Johnson, Paola Sandroni, Philip A Low, Michael J Joyner
• Journal: Journal of applied physiology (Bethesda, Md. : 1985) (J Appl Physiol (1985)) Vol. 97 Issue 5 Pg. 1978-84 (Nov 2004) ISSN: 8750-7587 [Print] United States
• PMID: 15273244 (Publication Type: Clinical Trial, Journal Article, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Adrenergic alpha-Agonists
• Catecholamines
• Vasoconstrictor Agents
• Midodrine

Topics

• Adrenergic alpha-Agonists (therapeutic use)
• Aged
• Autonomic Nervous System Diseases (complications, drug therapy, physiopathology)
• Bicycling
• Blood Pressure (drug effects)
• Cardiovascular System (physiopathology)
• Catecholamines (blood)
• Exercise
• Female
• Forearm (blood supply)
• Humans
• Hypotension (drug therapy, etiology)
• Ischemia (physiopathology)
• Leg (blood supply)
• Male
• Middle Aged
• Midodrine (therapeutic use)
• Physical Endurance
• Regional Blood Flow (drug effects)
• Supine Position
• Vasoconstrictor Agents (therapeutic use)