Smoking reduces myocardial flood flow; vitamin C restores flow

LONDON, 13 September (SPIS MedWire). The pro-oxidant effect of cigarette smoke extends to the coronary microcirculation, thereby reducing myocardial blood flow, concludes a multicenter clinical trial published 12 September (Circulation 2000, 102:1233-1238). A second finding from the same study is that coronary flow is restored by administration of the antioxidant vitamin C. The researchers used positron emission tomography to measure coronary flow reserve – an integrated measure of coronary flow – in 11 smokers and eight control subjects before and after administration of vitamin C. At baseline, coronary flow reserve was reduced by 21% in smokers compared with control subjects (p<0.05) but was normalized after vitamin C, whereas the drug had no effect in control subjects. Short-term infusion of vitamin C, the team reports, "almost completely reverses microcirculatory dysfunction in asymptomatic smokers." These results suggest that increased productivity or activity of oxygen-derived free radicals contributes to...