Cigarette smoke elicits relaxation of renal arteries.
BACKGROUND
Epidemiological studies suggest that cigarette smoking - probably by eliciting hyperperfusion - increases glomerular filtration rate; thus, we hypothesized that cigarette smoke affects the vasomotor tone of renal arteries.


METHODS
Acute changes in the resistance index of a segmental renal artery were measured in healthy individuals during smoking. In addition, the effects of water-soluble components of cigarette smoke on the isometric tension of isolated rat renal arteries were investigated in various conditions.


RESULTS
In humans, cigarette smoking transiently reduced the resistance index of the renal artery segments (83·25 ± 5·67% of the baseline, P < 0·05). In the experimental model, water-soluble components of cigarette smoke (wCS) - either nicotinic or nicotine-free - elicited dose-dependent relaxations of rat isolated renal arteries (1% solution of nicotinic wCS: 41·18 ± 14·86% relaxation, 5% nicotinic wCS: 79·28 ± 8·91% relaxation, 10% nicotinic wCS 90·3 ± 6·1% relaxation, P < 0·05), which were not affected by removal of the endothelium, or by the soluble guanylate cyclase inhibitor oxadiazolo-quinoxalin-1, or the non specific potassium channel blocker tetraethylammonium, or the K(ATP) channel blocker glibenclamide. However, relaxations were reduced by catalase (1000 U mL⁻¹ catalase + 5% nicotinic wCS: 49·71 ± 18·4%, P < 0·05) and enhanced by superoxide dismutase (200 U mL⁻¹ SOD + 5% nicotinic wCS: 95·7 ± 2·3%, P < 0·05).


CONCLUSIONS
On the basis of these findings, we propose that cigarette smoking could contribute to the increased glomerular filtration rate observed in healthy smokers. In addition, cigarette smoke via hydrogen peroxide mediation reduces vasomotor tone of renal arteries, which could lead to hyperperfusion of kidneys.
2nd Department of Internal Medicine and Nephrology Center, University of Pécs, Pécs, Hungary.
Richárd
R
Halmai
István András
IA
Szijártó
Eszter
E
Fehér
Gábor
G
Fésüs
Gergo A
GA
Molnár
Pál
P
Brasnyó
Ferenc
F
Fülöp
Maik
M
Gollasch
Akos
A
Koller
István
I
Wittmann
D000328:Adult; D000818:Animals; D006801:Humans; D008297:Male; D009538:Nicotine / Q000494:pharmacology*; D051381:Rats; D012077:Renal Artery / Q000187:drug effects*; D012907:Smoking; D013223:Statistics as Topic; D014664:Vasodilation / Q000187:drug effects*; D014665:Vasodilator Agents / Q000494:pharmacology*; D055815:Young Adult
D014665:Vasodilator Agents; D009538:Nicotine