Vitamin C augments the renal response to L-arginine in smokers.
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.
Schneider
Markus P
MP
Department of Medicine/Nephrology, University of Erlangen-Nürnberg, Germany.
Klingbeil
Arnfried U
AU
Delles
Christian
C
Schmidt
Bernhard M W
BM
John
Stefan
S
Schmieder
Roland E
RE
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*
D000975:Antioxidants; D019323:omega-N-Methylarginine; D001120:Arginine; D001205:Ascorbic Acid