title: Effects of oxidative stress on endothelial modulation of contractions in aorta from renal hypertensive rats.
abstract: BACKGROUND
  Endothelial dysfunction is linked to exaggerated production of superoxide anions. This study was conducted to examine the effects of oxidative stress on endothelial modulation of contractions in chronic two-kidney, one-clip (2K1C) renal hypertensive rats.
  
  
  METHODS
  The 2K1C hypertension was induced by clipping the left renal artery; age-matched rats receiving sham treatment served as controls. Thoracic aortae were isolated and mounted in tissue baths for measurement of isometric tension.
  
  
  RESULTS
  Norepinephrine-induced contraction was augmented by the removal of the endothelium, which was more pronounced in sham rats than in 2K1C rats. Nω-nitro-L-arginine methyl ester, an inhibitor of nitric oxide production, had a similar augmenting effect. Vitamin C inhibited the contraction in aortic rings with intact endothelium from 2K1C rats but not from sham rats. The contraction was also suppressed by treatment with diphenyleneiodonium or apocynin, inhibitors of nicotinamide adenine dinucleotide/nicotinamide adenine dinucleotide phosphate (NADH/NADPH) oxidase, in the aortae with intact endothelium from 2K1C rats but not in those from sham rats. Superoxide anions generated by xanthine oxidase/hypoxanthine enhanced the contraction in the aortae with intact endothelium from sham rats, but had no effect in 2K1C rats. Enhanced contractile responses to norepinephrine by xanthine oxidase/hypoxanthine in sham rats were reversed by vitamin C.
  
  
  CONCLUSIONS
  These results suggest that the effect on endothelial modulation of endothelium-derived nitric oxide is impaired in 2K1C hypertension. The impairment is, at least in part, related to increased production of superoxide anions by NADH/NADPH oxidase.
authors.affiliation: Department of Physiology, College of Medicine, Chosun University, Gwangju, Korea.
authors.forename: Seok
authors.initials: S
authors.lastname: Choi
authors.affiliation: Department of Psychiatry, College of Medicine, Chosun University, Gwangju, Korea.
authors.forename: Hye Rang
authors.initials: HR
authors.lastname: Shin
authors.affiliation: Department of Psychiatry, College of Medicine, Chosun University, Gwangju, Korea.
authors.forename: Sang Hoon
authors.initials: SH
authors.lastname: Kim
authors.affiliation: Department of Physiology, College of Medicine, Chosun University, Gwangju, Korea.
authors.forename: Mi Jung
authors.initials: MJ
authors.lastname: Lee
authors.affiliation: Department of Physiology, College of Medicine, Chosun University, Gwangju, Korea.
authors.forename: Jae Yeoul
authors.initials: JY
authors.lastname: Jun
authors.affiliation: Department of Internal Medicine, College of Medicine, Chosun University, Gwangju, Korea.
authors.forename: Hyun Lee
authors.initials: HL
authors.lastname: Kim
authors.affiliation: Department of Internal Medicine, College of Medicine, Chosun University, Gwangju, Korea.
authors.forename: Jong Hoon
authors.initials: JH
authors.lastname: Chung
authors.affiliation: Department of Physiology, College of Medicine, Chosun University, Gwangju, Korea.
authors.forename: Cheol Ho
authors.initials: CH
authors.lastname: Yeum
keywords: Endothelium; Oxidative stress; Renal hypertension; Superoxide