The Study
Contribution of nitric oxide to metabolic coronary vasodilation in the human heart.
This study didn't randomly assign people to groups, so we can't say for sure that blocking nitric oxide directly causes less blood flow. But it did show that when they blocked nitric oxide, blood vessels didn't open as much — so we know there's a strong link between nitric oxide and blood flow in the heart.
Analysis score
Maximum 90 for a randomized controlled trial.
Where the score came from
When your heart works harder, tiny blood vessels in your heart open up to let in more blood. Nitric oxide is a chemical your blood vessels make to help them open. This study tested what happens when you block nitric oxide.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 541 / 100
Quality score
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Yes — if your heart can't widen its blood vessels properly during exercise or stress, it may not get enough oxygen, causing chest pain even without blocked arteries.
- 2Without nitric oxide, blood flow increased 38% less during heart pacing.
- 3In healthy people, heart arteries widened 9% during pacing — but narrowed 6% when nitric oxide was blocked.
- 4People with high blood pressure or cholesterol had much less widening even before blocking nitric oxide.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Circulation
Year
1995
Authors
A. Quyyumi, N. Dakak, N. P. Andrews, D. Gilligan, J. Panza, R. Cannon
Related Content
Claims (6)
Nitric oxide causes blood vessel walls to relax, which allows more blood to flow through and lowers resistance in the blood vessels.
Patients with hypertension, high cholesterol, or diabetes have reduced widening of small heart blood vessels during stress testing, which reflects impaired function of the blood vessel lining related to nitric oxide signaling.
In people without cardiovascular risk factors, nitric oxide causes the main blood vessels around the heart to widen during metabolic stress; blocking nitric oxide makes these vessels narrow instead.
Blocking nitric oxide does not change how coronary arteries widen when sodium nitroprusside or adenosine is applied, showing that nitric oxide is not involved in these specific dilation mechanisms.
When nitric oxide production is blocked in people with healthy coronary arteries, the resistance in the heart's blood vessels increases by 16% and the main artery supplying the heart narrows by 11% while at rest.
When nitric oxide production is blocked in the coronary arteries of patients with healthy heart vessels, the increase in blood flow during paced heart activity is reduced by 38%, showing that nitric oxide is necessary for this blood flow response.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.