6-Nitrodopamine is released by human umbilical cord vessels and modulates vascular reactivity

AIMS: Human umbilical cord vessels (HUCV) release dopamine and nitric oxide (NO). This study aims to verify whether HUCV release nitrocatecholamines such as 6-nitrodopamine (6-ND). MAIN METHODS: Liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) was used to identify 6-ND release from HUCV rings incubated in Krebs-Henseileit's solution. Vascular reactivity of HUCV rings was tested (with and without endothelium integrity) by suspension of the rings in an organ bath under isometric tension and application of 6-ND and other known mediators. KEY FINDINGS: -receptor antagonist SCH-23390 (10 nM) abolished relaxation induced by fenoldopam but did not affect those induced by 6-ND. SIGNIFICANCE: -receptor antagonist in this tissue. This represents a novel mechanism by which NO may modulate vascular reactivity independently of cGMP production.