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Updated: Oct 9, 2026

Oxygenation-sensitive Cardiac MRI with Vasoactive Breathing Maneuvers for the Non-invasive Assessment of Coronary Microvascular Dysfunction
Published on: August 17, 2022
Hydrogen sulfide-mediated vasodilation requires heme oxygenase-derived carbon monoxide
Background:
Hydrogen sulfide (H 2 S) is an important endothelial-derived vasodilator, but the signaling mechanism remains incompletely understood. We previously demonstrated that H 2 S-mediated vasodilation requires transient receptor potential vanilloid type 4 (TRPV4) channels. Because H 2 S has been reported to enhance heme oxygenase (HO) activity and HO-derived carbon monoxide (CO) regulates endothelial signaling, we hypothesized that H 2 S-mediated vasodilation requires HO-2-derived CO.
Methods:
Pressure myography was performed in isolated rat mesenteric arteries to determine the contribution of HO, TRPV4, eBK, and SK/IK channels to H 2 S-mediated vasodilation. HO-2 sulfhydration was assessed using a maleimide assay, and spatial association among HO-2 and TRPV4 was examined using proximity ligation assays in human aortic endothelial cells.
Results:
H 2 S Selicited concentration-dependent vasodilation that was abolished by HO inhibition. Repletion of CO restored H 2 S-mediated vasodilation in the presence of HO inhibition. CO-mediated vasodilation was abolished by TRPV4 and SK/IK inhibition but was unaffected by eBK inhibition. H 2 S increased HO-2 sulfhydration and enhanced HO activity. In endothelial cells, HO-2 and TRPV4 exhibited close spatial association.
Conclusions:
These findings support a model in which H 2 S stimulates HO-2-derived CO production, leading to TRPV4-dependent endothelial signaling, SK/IK activation, and vasodilation. Together, the data support the existence of an endothelial HO-2/TRPV4/SK/IK signaling domain that contributes to H 2 S-mediated vascular reactivity.
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