title: Estradiol counteracts oxidized LDL-induced asymmetric dimethylarginine production by cultured human endothelial cells.
abstract: OBJECTIVE
  Asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide (NO) synthase, is a novel cardiovascular risk factor produced by endothelial cells. ADMA levels are mainly regulated by the activity of dimethylarginine dimethylaminohydrolases (DDAH). Endothelial release of ADMA is increased in the presence of oxidized LDL cholesterol (oxLDL), whereas estrogens stimulate NO production by endothelial cells by increasing both expression and activity of NO synthase and by reducing ADMA levels. Thus, the aim of the present study was to evaluate the estradiol effects on the DDAH/ADMA/NO pathway in cultured human umbilical vein endothelial cells (HUVEC) exposed to LDL.
  
  
  METHODS
  After 24 h of exposure to various treatments, culture medium was collected to measure NO production by using an amperometric sensor specific for NO, and to measure dimethylarginines by high-performance liquid chromatography (HPLC). DDAH-I and II mRNA expression and protein content were quantified by real-time PCR assay and immunoblotting, respectively.
  
  
  RESULTS
  Exposure of HUVEC to 100 microg/mL oxLDL, but not to 100 microg/mL of native LDL (nLDL), reduced DDAH-II expression at both the mRNA as well as the protein levels, which in turn increased ADMA levels and reduced NO production. Estradiol (1 nM) alone increased DDAH-II mRNA and protein expression, which reduced ADMA levels and increased NO production. In cells exposed to estradiol in combination with either nLDL or oxLDL, levels of DDAH-II, ADMA, and NO were the same as those for estradiol alone.
  
  
  CONCLUSIONS
  Estradiol completely reverses the effects induced by oxLDL on the DDAH/ADMA/NO pathway.
authors.affiliation: Department of Physiology, University of Valencia, Spain.
authors.forename: Elena
authors.initials: E
authors.lastname: Monsalve
authors.forename: Pilar J
authors.initials: PJ
authors.lastname: Oviedo
authors.forename: Miguel Angel
authors.initials: MA
authors.lastname: García-Pérez
authors.forename: Juan J
authors.initials: JJ
authors.lastname: Tarín
authors.forename: Antonio
authors.initials: A
authors.lastname: Cano
authors.forename: Carlos
authors.initials: C
authors.lastname: Hermenegildo
mesh_terms: D000328:Adult; D000581:Amidohydrolases / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D000704:Analysis of Variance; D001120:Arginine / Q000031:analogs & derivatives* / Q000096:biosynthesis; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D004563:Electrochemistry; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism*; D004730:Endothelium, Vascular; D004958:Estradiol / Q000494:pharmacology*; D015870:Gene Expression; D006801:Humans; D015151:Immunoblotting / Q000379:methods; D008077:Lipoproteins, LDL / Q000378:metabolism / Q000494:pharmacology*; D009569:Nitric Oxide / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D008077:Lipoproteins, LDL; D012333:RNA, Messenger; C487735:dimethylarginine; C099252:oxidized low density lipoprotein; D009569:Nitric Oxide; D004958:Estradiol; D001120:Arginine; D019001:Nitric Oxide Synthase; D000581:Amidohydrolases; C059999:dimethylargininase