title: Vitamin C augments the renal response to L-arginine in smokers.
abstract: BACKGROUND
  In the coronary and the forearm circulations, endothelium-dependent vasomotion is impaired in smokers, but can be augmented by -arginine or vitamin C. We examined whether smoking similarly affects the renal circulation.
  
  
  METHODS
  In 20 smokers (age 26 +/- 4 years) and in 20 non-smokers (age 28 +/- 3 years) changes of renal plasma flow (RPF), glomerular filtration rate (GFR), blood pressure and heart rate in response to the subsequent intravenous infusions of N(G)-monomethyl--arginine (L-NMMA), -arginine and -arginine plus vitamin C were studied by use of a constant infusion input clearance technique.
  
  
  RESULTS
  Systemic haemodynamic parameters did not differ between smokers and non-smokers during each experimental phase. At baseline, RPF and GFR were similar between the groups. The infusion of L-NMMA led to a similar decrease of RPF, while GFR did not change in either group. During the infusion of -arginine RPF increased similarly. Finally, the co-infusion of -arginine plus vitamin C led to a significantly greater increase of RPF (+277 +/- 395 vs +79 +/- 76 ml/min, P = 0.03) and GFR (+12.1 +/- 10.6 vs +3.4 +/- 11.2 ml/min, P = 0.02) in smokers as compared to non-smokers.
  
  
  CONCLUSIONS
  L-NMMA-induced vasoconstriction of the renal vasculature was similar in smokers compared to non-smokers. -arginine alone induced a similar increase of RPF. The co-infusion of vitamin C and -arginine led to a greater increase of RPF and GFR in smokers. This might suggest that oxidative stress is increased in the renal vasculature of smokers.
authors.affiliation: Department of Medicine/Nephrology, University of Erlangen-Nürnberg, Germany.
authors.forename: Markus P
authors.initials: MP
authors.lastname: Schneider
authors.forename: Arnfried U
authors.initials: AU
authors.lastname: Klingbeil
authors.forename: Christian
authors.initials: C
authors.lastname: Delles
authors.forename: Bernhard M W
authors.initials: BM
authors.lastname: Schmidt
authors.forename: Stefan
authors.initials: S
authors.lastname: John
authors.forename: Roland E
authors.initials: RE
authors.lastname: Schmieder
mesh_terms: D000293:Adolescent; D000328:Adult; D000975:Antioxidants / Q000494:pharmacology*; D001120:Arginine / Q000494:pharmacology*; D001205:Ascorbic Acid / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects; D004357:Drug Synergism; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007262:Infusions, Intravenous; D007668:Kidney / Q000503:physiopathology*; D008297:Male; D012039:Regional Blood Flow / Q000187:drug effects; D012907:Smoking / Q000503:physiopathology*; D014664:Vasodilation / Q000187:drug effects; D019323:omega-N-Methylarginine / Q000494:pharmacology*
chemical_list: D000975:Antioxidants; D019323:omega-N-Methylarginine; D001120:Arginine; D001205:Ascorbic Acid