title: Asymmetric dimethylarginine (ADMA) determines the improvement of hepatic endothelial dysfunction by vitamin E in cirrhotic rats.
abstract: BACKGROUND
  Hepatic endothelial dysfunction (HED), which is caused by decreased hepatic nitric oxide (NO) bioavailability and increased lipid peroxidation, contributes to portal hypertension, which is a characteristic of cirrhosis. Asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase (NOS), is involved in cirrhosis-related HED and portal hypertension.
  
  
  OBJECTIVE
  We evaluated the effect of vitamin E treatment on the lipid peroxidation, HED and portal hypertension in cirrhotic rats.
  
  
  METHODS
  The common bile duct ligation (BDL)-induced cirrhotic rats were treated orally either with vehicle or with vitamin E for 1 month immediately after BDL. Systemic and portal haemodynamics, the magnitude of the increase in portal pressure induced by volume expansion, HED, oxidative stress, levels of ADMA, various proteins and mRNAs were then measured.
  
  
  RESULTS
  In the vitamin E-treated BDL rats, a decrease in portal pressure was associated with an attenuation of the increased portal pressure induced by volume expansion. In isolated and perfused BDL rat livers, the vitamin E treatment significantly inhibited the (paradoxical) vasoconstriction response to methoxamine and acetylcholine (HED), and this was abolished by the presence of NOS. Vitamin E decreased ADMA synthesizing enzyme PRMT1 expression and the level of thiobarbituric acid-reactive substances (TBARS) in the liver, while increasing the levels of hepatic ADMA metabolizing enzyme DDAH2, eNOS, phosphor-eNOS, ADMA level and superoxide dismutase activity.
  
  
  CONCLUSIONS
  The administration of vitamin E suppressed hepatic ADMA and oxidative stress in the cirrhotic liver circulation, and therefore increases NO bioavailability, which improved HED and portal hypertension.
authors.affiliation: Division of General Medicine, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.
authors.forename: Ying-Ying
authors.initials: YY
authors.lastname: Yang
authors.forename: Tzung-Yan
authors.initials: TY
authors.lastname: Lee
authors.forename: Yi-Tsau
authors.initials: YT
authors.lastname: Huang
authors.forename: Che-Chang
authors.initials: CC
authors.lastname: Chan
authors.forename: Yi-Chen
authors.initials: YC
authors.lastname: Yeh
authors.forename: Fa-Yauh
authors.initials: FY
authors.lastname: Lee
authors.forename: Shou-Dong
authors.initials: SD
authors.lastname: Lee
authors.forename: Han-Chieh
authors.initials: HC
authors.lastname: Lin
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D001120:Arginine / Q000031:analogs & derivatives* / Q000494:pharmacology; D004357:Drug Synergism; D042783:Endothelial Cells / Q000187:drug effects* / Q000473:pathology; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006439:Hemodynamics / Q000187:drug effects; D006975:Hypertension, Portal / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D066298:In Vitro Techniques; D015227:Lipid Peroxidation / Q000187:drug effects; D008099:Liver / Q000098:blood supply / Q000187:drug effects; D008106:Liver Cirrhosis, Experimental / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects; D010477:Perfusion; D051381:Rats; D017207:Rats, Sprague-Dawley; D014661:Vasoconstriction / Q000187:drug effects; D014810:Vitamin E / Q000494:pharmacology*
chemical_list: D000975:Antioxidants; D004791:Enzyme Inhibitors; D014810:Vitamin E; D009569:Nitric Oxide; C018524:N,N-dimethylarginine; D001120:Arginine