title: Renal oxygenation changes during water loading as evaluated by BOLD MRI: effect of NOS inhibition.
abstract: OBJECTIVE
  To demonstrate a possible role for endogenous release of nitric oxide in determining the response of water loading on intrarenal oxygenation as evaluated by blood oxygenation level-dependent (BOLD) magnetic resonance imaging (MRI).
  
  
  METHODS
  Twelve Sprague Dawley rats (weight 344.9 ± 40.6 g) were equally divided into two groups, A and B. Water loading was implemented by continuous infusion of hypotonic saline containing glucose (0.25% NaCl, 0.5% glucose). Rats in group A were subject to water loading alone, while group B rats were dosed with N-nitro-L-arginine methyl ester, (L-NAME) (10.0 mg/kg) prior to water loading. T(2) *-weighted images of the kidneys were obtained on a Siemens 3T Verio MRI scanner using a multiple gradient recalled echo (mGRE) sequence.
  
  
  RESULTS
  Consistent with previous reports, group A exhibited a significant decrease in medullary R(2) * during water loading (40.64 ± 1.10 s(-1) to 34.68 ± 1.49 s(-1) , P < 0.05). On the other hand, in group B there was no decrease in R(2) * during water loading (48.11 ± 2.38 s(-1) to 51.06 ± 2.18 s(-1) ). The increased prewater loading R(2) * is due to the pretreatment with L-NAME (40.82 ± 3.23 s(-1) to 48.11 ± 2.38 s(-1) , P < 0.05).
  
  
  CONCLUSIONS
  Our data suggest for the first time a role for endogenous nitric oxide in determining the response of renal medullary oxygenation to water loading.
authors: Department of Radiology, NorthShore University Health System, Evanston, IL, USA.
authors: Muhammad
authors: M
authors: Haque
authors: Tammy
authors: T
authors: Franklin
authors: Pottumarthi
authors: P
authors: Prasad
mesh_terms: D000818:Animals; D004231:Diuresis; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005947:Glucose / Q000378:metabolism; D006801:Humans; D007668:Kidney / Q000378:metabolism*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008954:Models, Biological; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000493:pharmacokinetics; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D010100:Oxygen / Q000737:chemistry*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014867:Water / Q000737:chemistry
chemical_list: D004791:Enzyme Inhibitors; D014867:Water; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D005947:Glucose; D010100:Oxygen; D019331:NG-Nitroarginine Methyl Ester