title: Hydrogen peroxide mediates endothelium-dependent dilation of coronary arterioles in obese rats on a low-carbohydrate diet.
abstract: OBJECTIVE
  Endothelium-dependent vasodilation of coronary arterioles is impaired in obese rats and may be improved by a LCD. The aim of this study is to elucidate the mechanism by which this improvement occurs.
  
  
  METHODS
  We used four groups of male Zucker rats: lean and obese on either SD or LCD. Coronary arterioles were cannulated and pressurized for diameter measurements during administration of acetylcholine or sodium nitroprusside or during flow. Real-time PCR was performed to quantify mRNA expression of CuZnSOD and catalase.
  
  
  RESULTS
  The LCD significantly increased endothelium-dependent dilation in the obese rats. l-NAME and indomethacin reduced responses to flow and acetylcholine in the lean rats without any effect on the obese on either diet. In contrast, TEA and catalase blocked flow-dependent and acetylcholine-induced dilation in the obese on either diet, while no effect was observed on the lean. The LCD in the obese significantly up-regulated catalase mRNA expression and slightly increased CuZnSOD mRNA levels.
  
  
  CONCLUSIONS
  A LCD improves endothelium-dependent vasodilation of coronary arterioles in obese rats through the production of H2 O2 which acts as a hyperpolarizing factor, independent of nitric oxide and PGI2 .
authors.affiliation: Department of Cardiovascular Disease, University of Siena, Siena, Italy.
authors.forename: Marta
authors.initials: M
authors.lastname: Focardi
authors.forename: Andrea
authors.initials: A
authors.lastname: Picchi
authors.forename: Sandra
authors.initials: S
authors.lastname: Donnini
authors.forename: Matteo
authors.initials: M
authors.lastname: Cameli
authors.forename: Marina
authors.initials: M
authors.lastname: Ziche
authors.forename: Mario
authors.initials: M
authors.lastname: Marzilli
authors.forename: Sergio
authors.initials: S
authors.lastname: Mondillo
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001160:Arterioles / Q000378:metabolism / Q000469:parasitology / Q000473:pathology; D003326:Coronary Circulation / Q000187:drug effects*; D004040:Dietary Carbohydrates / Q000494:pharmacology*; D004730:Endothelium, Vascular / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006861:Hydrogen Peroxide / Q000378:metabolism*; D008297:Male; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009599:Nitroprusside / Q000494:pharmacology; D009765:Obesity / Q000178:diet therapy / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D051381:Rats; D011924:Rats, Zucker; D014664:Vasodilation / Q000187:drug effects*; D014665:Vasodilator Agents / Q000494:pharmacology
chemical_list: D004040:Dietary Carbohydrates; D004791:Enzyme Inhibitors; D014665:Vasodilator Agents; D009599:Nitroprusside; D006861:Hydrogen Peroxide; D000109:Acetylcholine; D019331:NG-Nitroarginine Methyl Ester
keywords: coronary arterioles; endothelium dysfunction; low-carbohydrate diet; obesity