Cellular redox state and endothelial dysfunction in mildly hyperhomocysteinemic cystathionine beta-synthase-deficient mice.
Previous in vitro experiments have shown that hyperhomocysteinemia leads to oxidative inactivation of nitric oxide, in part by inhibiting the expression of cellular glutathione peroxidase (GPx-1). To elucidate the role of intracellular redox status on homocysteine-induced endothelial dysfunction and oxidant stress, heterozygous cystathionine beta-synthase-deficient (CBS(-/+)) and wild-type (CBS(+/+)) mice were treated with the cysteine donor L-2-oxothiazolidine-4-carboxylic acid (OTC). CBS(-/+) mice had significantly lower GPx-1 activity compared with their CBS(+/+) littermates, and OTC treatment led to a modest increase in tissue GPx-1 activity and significant increases in total thiols and in reduced glutathione levels in both CBS(+/+) and CBS(-/+) mice. Superfusion of the mesentery with beta-methacholine or bradykinin produced dose-dependent vasodilation of mesenteric arterioles in CBS(+/+) mice and in CBS(+/+) mice treated with OTC. In contrast, mesenteric arterioles from CBS(-/+) mice manifested dose-dependent vasoconstriction in response to both agonists. OTC treatment of CBS(-/+) mice restored normal microvascular vasodilator reactivity to beta-methacholine and bradykinin. These findings demonstrate that mild hyperhomocysteinemia leads to endothelial dysfunction in association with decreased bioavailable nitric oxide. Increasing the cellular thiol and reduced glutathione pools and increasing GPx-1 activity restores endothelial function. These findings emphasize the importance of intracellular redox balance for nitric oxide bioactivity and endothelial function.
Weiss
Norbert
N
Whitaker Cardiovascular Institute, Evans Department of Medicine, Boston University School of Medicine, Boston, MA 02118-2394, USA.
Heydrick
Stanley
S
Zhang
Ying-Yi
YY
Bierl
Charlene
C
Cap
André
A
Loscalzo
Joseph
J
D000818:Animals; D001920:Bradykinin / Q000494:pharmacology; D003541:Cystathionine beta-Synthase / Q000172:deficiency; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000187:drug effects / Q000503:physiopathology; D005979:Glutathione Peroxidase / Q000378:metabolism*; D006710:Homocysteine / Q000097:blood; D020138:Hyperhomocysteinemia / Q000378:metabolism* / Q000503:physiopathology; D008099:Liver / Q000378:metabolism; D008643:Mesentery / Q000098:blood supply; D016210:Methacholine Chloride / Q000494:pharmacology; D051379:Mice; D009569:Nitric Oxide / Q000378:metabolism*; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D011761:Pyrrolidonecarboxylic Acid; D013438:Sulfhydryl Compounds / Q000097:blood; D013844:Thiazoles / Q000494:pharmacology; D053778:Thiazolidines; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology*
D013438:Sulfhydryl Compounds; D013844:Thiazoles; D053778:Thiazolidines; D006710:Homocysteine; D016210:Methacholine Chloride; D009569:Nitric Oxide; D005979:Glutathione Peroxidase; D003541:Cystathionine beta-Synthase; D001920:Bradykinin; D011761:Pyrrolidonecarboxylic Acid; C029536:2-oxothiazolidine-4-carboxylic acid