title: Homocysteine impairs coronary artery endothelial function by inhibiting tetrahydrobiopterin in patients with hyperhomocysteinemia.
abstract: Hyperhomocysteinemia (HHcy) has been associated with impaired vascular endothelial function. Our previous study demonstrated significantly higher secretion of the chemokine monocyte chemoattractant protein-1 from monocytes in response to lipopolysaccharide in patients with HHcy. In the present study, we investigated whether coronary endothelial function was damaged in patients with chronic HHcy (plasma level of homocysteine >15 μmol/l) and, if so, whether this impaired endothelial function is induced by the uncoupling of endothelial nitric oxide synthase (eNOS). When tetrahydrobiopterin levels are inadequate, eNOS is no longer coupled to l-arginine oxidation, which results in reactive oxygen species rather than nitric oxide production, thereby inducing vascular endothelial dysfunction. The 71 participants were divided into two groups, control (n = 50) and HHcy (n = 21). Quantification of coronary flow velocity reserve (CFVR) was after rest and after adenosine administration done by noninvasive Doppler echocardiography. Plasma levels of nitric oxide and tetrahydrobiopterin were significantly lower in patients with HHcy than in controls (99.54 ± 32.23 vs. 119.50 ± 37.68 μmol/l and 1.43 ± 0.46 vs. 1.73 ± 0.56 pmol/ml, all P < 0.05). Furthermore, CFVR was significantly lower in the HHcy than the control group (2.76 ± 0.49 vs. 3.09 ± 0.52, P < 0.05). In addition, plasma level of homocysteine was negatively correlated with CFVR. Chronic HHcy may contribute to coronary artery disease by inducing dysfunction of the coronary artery endothelium. The uncoupling of eNOS induced by HHcy in patients with chronic HHcy may explain this adverse effect in part.
authors.affiliation: Dept. of Endocrinology, Peking University Health Science Center, Beijing 100191, People's Republic of China.
authors.forename: Liyun
authors.initials: L
authors.lastname: He
authors.forename: Hui
authors.initials: H
authors.lastname: Zeng
authors.forename: Fuwang
authors.initials: F
authors.lastname: Li
authors.forename: Jieli
authors.initials: J
authors.lastname: Feng
authors.forename: Shan
authors.initials: S
authors.lastname: Liu
authors.forename: Jinbo
authors.initials: J
authors.lastname: Liu
authors.forename: Jie
authors.initials: J
authors.lastname: Yu
authors.forename: Jieming
authors.initials: J
authors.lastname: Mao
authors.forename: Tianpei
authors.initials: T
authors.lastname: Hong
authors.forename: Alex F
authors.initials: AF
authors.lastname: Chen
authors.forename: Xian
authors.initials: X
authors.lastname: Wang
authors.forename: Guang
authors.initials: G
authors.lastname: Wang
mesh_terms: D000328:Adult; D000368:Aged; D001708:Biopterins / Q000031:analogs & derivatives* / Q000378:metabolism; D001783:Blood Flow Velocity; D002851:Chromatography, High Pressure Liquid; D003331:Coronary Vessels / Q000378:metabolism / Q000503:physiopathology*; D004730:Endothelium, Vascular / Q000378:metabolism / Q000503:physiopathology*; D005260:Female; D006710:Homocysteine / Q000378:metabolism*; D006801:Humans; D020138:Hyperhomocysteinemia / Q000378:metabolism / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D018709:Statistics, Nonparametric
chemical_list: D006710:Homocysteine; D001708:Biopterins; D009569:Nitric Oxide; D052250:Nitric Oxide Synthase Type III; C003402:sapropterin