Ascorbic acid improves impaired venous and arterial endotheliumdependent dilation in smokers
Abstract
Aim: 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. Conclusion: Smokers
had impaired endothelium-dependent vasodilation responsiveness in both arterial
and venous systems. Ascorbic acid restores this responsiveness in smokers.
Keywords:
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. Conclusion: Smokers
had impaired endothelium-dependent vasodilation responsiveness in both arterial
and venous systems. Ascorbic acid restores this responsiveness in smokers.