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Therapy with nitroglycerin increases coronary vasoconstriction in response to acetylcholine
P R Caramori1, A G Adelman, E R Azevedo
1Department of Medicine, Mount Sinai Hospital, University of Toronto, Ontario, Canada.
Journal of the American College of Cardiology
|December 19, 1998
Summary
Nitroglycerin (GTN) therapy causes abnormal coronary artery responses to acetylcholine, leading to increased constriction. These changes persist for hours after stopping GTN, impacting nitrate tolerance and withdrawal safety.
Area of Science:
- Cardiovascular Medicine
- Pharmacology
- Vascular Biology
Background:
- Nitroglycerin (GTN) therapy can induce vascular biochemical changes, potentially increasing sensitivity to vasoconstrictors.
- Endothelial dysfunction is a key factor in various cardiovascular diseases.
Purpose of the Study:
- To determine if nitroglycerin (GTN) therapy alters coronary artery responses to acetylcholine, an endothelium-dependent vasodilator.
- To investigate the duration of these altered responses after GTN discontinuation.
Main Methods:
- Patients received transdermal GTN or no therapy for 5 days before catheterization.
- Quantitative angiography measured left anterior descending coronary artery (LAD) diameter changes in response to acetylcholine.
- Coronary responses were assessed in the morning and again 3 hours after GTN removal.
Main Results:
- The GTN group showed significantly greater coronary constriction to acetylcholine compared to the control group (-19.6% vs. -3.8%, p=0.01).
- This exaggerated constriction persisted for at least 3 hours after GTN discontinuation (-24.1% vs. -1.8%).
- The increase in coronary constriction in the GTN group was significantly greater than in the non-GTN group (p < 0.05).
Conclusions:
- Nitroglycerin (GTN) therapy induces abnormal coronary vasomotor responses to acetylcholine.
- These nitrate-induced vasomotor dysfunctions are persistent for up to 3 hours post-discontinuation.
- Findings suggest implications for nitrate tolerance and potential adverse events during nitrate withdrawal.