Uremic levels of BUN do not cause nitric oxide deficiency in rats with normal renal function

Shen Xiao, Aaron Erdely, Laszlo Wagner, Chris Baylis

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In vitro, 7 days of high blood urea nitrogen (BUN) inhibits endothelial L-arginine transport and nitric oxide synthase (NOS) activity. The present study investigates whether 7 days of high BUN in vivo influences renal hemodynamics, blood pressure (BP), and/or the nitric oxide (NO) system. Normal rats were fed low-nitrate food containing 30% urea for 7 days, which increased BUN (15 ± 1 to 69 ± 4 mg/100 ml, P < 0.001). High BUN did not reduce 24-hour urinary nitrite/nitrate excretion (a measure of total NO production). Baseline BP and renal hemodynamics were unaffected by high BUN as were the pressor and renal vasoconstrictor responses to acute NOS inhibition with NG-nitro-L-arginine-methyl ester. In addition, high BUN had no impact on renal cortical L-arginine concentration, density of either endothelial NOS or neuronal NOS protein, or renal cortical NOS activity. NOS activity in the brain cerebellum was also unaffected. In conclusion, high BUN did not lead to vasoconstriction or NO deficiency in rats with normal renal function. Further studies are needed to evaluate the effect of high BUN on the NO system in rats with progressive renal functional insufficiency.

Original languageEnglish
Pages (from-to)F996-F1000
JournalAmerican Journal of Physiology - Renal Physiology
Issue number6 49-6
Publication statusPublished - Jul 4 2001



  • Blood pressure
  • Blood urea nitrogen
  • Conscious rat
  • Renal vascular resistance

ASJC Scopus subject areas

  • Physiology
  • Urology

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