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Updated: Jun 2, 2026
08:41
Assessment of Vascular Tone Responsiveness using Isolated Mesenteric Arteries with a Focus on Modulation by Perivascular Adipose Tissues
Published on: June 3, 2019
The physiologic implications of isolated alpha(1) adrenergic stimulation
Robert H Thiele1, Edward C Nemergut, Carl Lynch
1Department of Anesthesiology, University of Virginia Health System, P.O. Box 800710, Charlottesville, VA 22908, USA. rht7w@virginia.edu
Anesthesia and Analgesia
|April 27, 2011
Summary
Phenylephrine and methoxamine, alpha-1 adrenergic receptor agonists, increase cardiac afterload and decrease cardiac output. These drugs do not improve myocardial energetics despite raising blood pressure.
Area of Science:
- Pharmacology
- Cardiovascular Physiology
Background:
- Phenylephrine and methoxamine are direct-acting alpha-1 adrenergic receptor (AR) agonists.
- Understanding their physiological effects is crucial for clinical applications.
Purpose of the Study:
- To review the physiological effects of phenylephrine and methoxamine, focusing on alpha-1 AR agonism.
- To evaluate their impact on cardiac afterload, cardiac output, and myocardial energetics.
Main Methods:
- Systematic review of 463 articles from PubMed searches and citation tracking.
- Inclusion criteria: human, randomized studies published in English.
- Incorporation of relevant articles from the peer-review process.
Main Results:
- Both agents increase cardiac afterload through increased vascular resistance and decreased compliance.
- Pure alpha-1 agonism increases arterial blood pressure but does not improve myocardial energetics.
- Cardiac output is decreased, likely due to increased venous resistance, despite potential transient increases in venous return.
Conclusions:
- Alpha-1 AR agonists like phenylephrine and methoxamine increase cardiac workload and decrease cardiac output.
- Their net effect on cardiovascular hemodynamics is complex, with potential negative impacts on organ perfusion.
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