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Nitroglycerin rebound associated with vascular, rather than platelet, hypersensitivity
1Department of Medicine, Montreal Heart Institute, University of Montreal Medical School, Quebec, Canada.
Journal of the American College of Cardiology
|December 29, 2000
Summary
Acute withdrawal of nitroglycerin (NTG) did not cause platelet hypersensitivity. Instead, vessel wall supersensitivity to vasoconstrictors like angiotensin II may explain rebound effects after stopping NTG therapy.
Area of Science:
- Cardiovascular Pharmacology
- Hemodynamics
- Platelet Physiology
Background:
- Nitroglycerin (NTG) is an antianginal drug limited by tolerance and rebound effects.
- Previous studies showed sustained platelet inhibition during NTG use.
- The impact of NTG cessation on platelet function and rebound is unknown.
Purpose of the Study:
- To investigate if acute nitroglycerin (NTG) withdrawal during hemodynamic tolerance is linked to platelet hypersensitivity.
- To explore the mechanisms behind rebound phenomena after NTG cessation.
Main Methods:
- Porcine aortic media exposed to arterial blood from pigs (n=8) treated with NTG patches for 48 hours.
- Evaluation of platelet function, blood pressure, and responses to angiotensin II before, during, and after NTG treatment.
Main Results:
- Mean arterial pressure returned to baseline by 48 hours and increased post-NTG withdrawal.
- Platelet deposition and aggregation were reduced during NTG treatment and remained decreased after cessation.
- Angiotensin II response was blunted during NTG treatment but increased significantly after withdrawal.
Conclusions:
- Vessel wall supersensitivity to vasoconstrictors (e.g., angiotensin II) may contribute to rebound after nitrate withdrawal.
- Platelet hyperactivity is unlikely to be the primary driver of the rebound phenomenon.