Objective:Most of the studies on the herb Chuanxiong Rhizoma(CR)have focused on the L-arginine-nitric oxide(NO)pathway,but the nitrate-nitrite-NO(NO3-NO2-NO)pathway was rarely investigated.Therefore,the aim of this study was to evaluate the effects and mechanisms of action of CR in coronary artery disease(CAD).Methods:The NO3-,NO2-and NO levels were examined in the NO3-NO2-NO pathway.High-performance ion chromatography was used to quantify NO3-and NO2-levels.Then,NO was quantified using a multi-functional enzyme marker with a fluorescent probe.The tension of aortic rings was measured using a multi myograph system.Results:High content of NO3-and low content of NO2-was found in CR,and which could potently convert NO3-to NO2-in the presence of endogenous reductase enzyme.Incubating human coronary artery endothelial cells(HCAECs)with CR-containing serum showed that CR significantly decreased the NO3-content and increased the levels of NO2-and NO in the cells under hypoxic conditions.In addition,CR sig-nificantly relaxed isolated aortic rings when the i-arginine-NO pathway was blocked.The optimal con-centration of CR for relaxation was 200 mg/mL.Conclusion:CR supplements large amounts of NO in cells and vessels to achieve relaxation via the NO3-NO2-NO pathway,thereby making up for the deficiency caused by the lack of NO after the L-arginine-NO pathway is suppressed.This study also supports the potential use of a traditional Chinese herb for future drug development.