Ascorbic acid improves impaired venous and arterial endothelium-dependent dilation in smokers.
OBJECTIVE
To compare the acute effects of ascorbic acid on vasodilation of veins and arteries in vivo.


METHODS
Twenty-six healthy non-smokers and 23 healthy moderate smokers were recruited in this study. The dorsal hand vein compliance technique and flow-mediated dilation were used. Dose-response curves to bradykinin and sodium nitroprusside were constructed to test the endothelium-dependent and -independent relaxation before and after acute infusion of ascorbic acid.


RESULTS
Smokers had an impaired venodilation with bradykinin compared with non-smokers (68.3%+/-13.2% vs 93.7%+/-20.1%, respectively; P<0.05). Ascorbic acid administration in the dorsal hand vein significantly increased the venodilation with bradykinin in smokers (68.3%+/-13.2% vs 89.5%+/-6.3% before and after infusion, respectively; P<0.05) but not in non-smokers (93.7%+/-20.1% vs 86.4%+/-12.4% before and after infusion, respectively). Similarly, the arterial response in smokers had an impaired endothelium-dependent dilation compared with that in non-smokers (8.8%+/-2.7% vs 15.2%+/-2.3%, respectively; P<0.05) and ascorbic acid restored this response in smokers (8.8%+/-2.7% vs 18.7%+/-6.5% before and after infusion, respectively; P<0.05), but no difference was seen in non-smokers (15.2%+/-2.3% vs 14.0%+/-4.4% before and after infusion, respectively). The endothelium-independent dilation did not differ in both the groups studied. No important hemodynamic change was detected using the Portapress device.


CONCLUSIONS
Smokers had impaired endothelium-dependent vasodilation responsiveness in both arterial and venous systems. Ascorbic acid restores this responsiveness in smokers.
de Sousa
Marcio Goncalves
MG
Cardiovascular Pharmacology and Cardiology, Clinical Hospital of Campinas and Faculty of Medical Sciences, State University of Campinas, 13081-970, Campinas, Sao Paulo, Brazil.
Yugar-Toledo
Juan Carlos
JC
Rubira
Marcelo
M
Ferreira-Melo
Silvia Elaine
SE
Plentz
Rodrigo
R
Barbieri
Deise
D
Consolim-Colombo
Fernanda
F
Irigoyen
Maria Claudia
MC
Moreno
Heitor
H
D000328:Adult; D001205:Ascorbic Acid / Q000494:pharmacology*; D001916:Brachial Artery / Q000503:physiopathology; D001920:Bradykinin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000187:drug effects*; D005260:Female; D006225:Hand / Q000098:blood supply; D006801:Humans; D008297:Male; D009599:Nitroprusside / Q000494:pharmacology; D012907:Smoking / Q000503:physiopathology*; D014664:Vasodilation / Q000187:drug effects*; D014680:Veins / Q000503:physiopathology
D009599:Nitroprusside; D001205:Ascorbic Acid; D001920:Bradykinin