title: Role of ceramide in TNF-alpha-induced impairment of endothelium-dependent vasorelaxation in coronary arteries.
abstract: The present study tested the hypothesis that ceramide, a sphingomylinase metabolite, serves as an second messenger for tumor necrosis factor-alpha (TNF-alpha) to stimulate superoxide production, thereby decreasing endothelium-dependent vasorelaxation in coronary arteries. In isolated bovine small coronary arteries, TNF-alpha (1 ng/ml) markedly attenuated vasodilator responses to bradykinin and A-23187. In the presence of N(G)-nitro-L-arginine methyl ester, TNF-alpha produced no further inhibition on the vasorelaxation induced by these vasodilators. With the use of 4,5-diaminofluorescein diacetate fluorescence imaging analysis, bradykinin was found to increase nitric oxide (NO) concentrations in the endothelium of isolated bovine small coronary arteries, which was inhibited by TNF-alpha. Pretreatment of the arteries with desipramine (10 microM), an inhibitor of acidic sphingomyelinase, tiron (1 mM), a superoxide scavenger, and polyethylene glycol-superoxide dismutase (100 U/ml) largely restored the inhibitory effect of TNF-alpha on bradykinin- and A-23187-induced vasorelaxation. In addition, TNF-alpha activated acidic sphingomyelinase and increased ceramide levels in coronary endothelial cells. We conclude that TNF-alpha inhibits NO-mediated endothelium-dependent vasorelaxation in small coronary arteries via sphingomyelinase activation and consequent superoxide production in endothelial cells.
authors.affiliation: Department of Pharmacology and Toxicology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA.
authors.forename: David X
authors.initials: DX
authors.lastname: Zhang
authors.forename: Fu-Xian
authors.initials: FX
authors.lastname: Yi
authors.forename: Ai-Ping
authors.initials: AP
authors.lastname: Zou
authors.forename: Pin-Lan
authors.initials: PL
authors.lastname: Li
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D002417:Cattle; D002518:Ceramides / Q000378:metabolism*; D003331:Coronary Vessels / Q000187:drug effects* / Q000502:physiology; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism; D016166:Free Radical Scavengers / Q000494:pharmacology; D005609:Free Radicals / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D011092:Polyethylene Glycols / Q000494:pharmacology; D013108:Sphingomyelin Phosphodiesterase / Q000378:metabolism; D013482:Superoxide Dismutase / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D014664:Vasodilation / Q000187:drug effects* / Q000502:physiology
chemical_list: D000970:Antineoplastic Agents; D002518:Ceramides; D016166:Free Radical Scavengers; D005609:Free Radicals; D014409:Tumor Necrosis Factor-alpha; D009569:Nitric Oxide; D011092:Polyethylene Glycols; D013482:Superoxide Dismutase; C063471:polyethylene glycol-superoxide dismutase; D013108:Sphingomyelin Phosphodiesterase