Vitamin C improves endothelial function of epicardial coronary arteries inpatients with hypercholesterolaemia or essential hypertension - assessed by cold presser testing

Aims There is evidence that formation of free radicals increases in patient s with hypertension or hypercholesterolaemia, which may contribute to endot helial dysfunction of epicardial coronary arteries due to inactivation of t he vasodilator NO. The present study was designed to test whether the abnor mal constriction of epicardial coronary arteries due to sympathetic stimula tion by the cold presser test in patients with essential hypertension or hy percholesterolaemia could be reversed by administration of the antioxidant vitamin C. Methods and Results In 28 patients without relevant coronary artery stenosi s the cold presser test was performed before and after a 3 g infusion of vi tamin C. In five normal controls the cold presser test led to a similar inc rease in luminal area before and after vitamin C (3.7 +/- 1.3% and 1.9 +/- 0.8%, ns vs before vitamin C). In nine hypercholesterolaemic patients the c old presser test led to a -14.1+/-28% reduction in cross-sectional area bef ore vitamin C. This constriction was significantly improved after vitamin C to -7.6%+/-2.0, P=0.027 vs before vitamin C. In nine hypertensive patients , the cold presser test led to a -17.1+/-3.2% decrease in cross-sectional a rea before vitamin C, which was improved to -7.1+/-3.1 after vitamin C, P=0 .004 vs before vitamin C. This increase in luminal area was significant in each group in comparison with normal controls teach P<0.05). Administration of saline (placebo group, five patients) had no significant effect on cold presser test-induced constriction (-6.9+/-3.9% before and -6.8+/-3.7% afte r saline). Conclusion The antioxidant vitamin C reverses cold presser test-induced vas oconstriction of epicardial coronary arteries in patients with hypertension or hypercholesterolaemia. Our data suggest that enhanced oxidative stress contributes to impaired endothelial function in this patient population. (C ) 1999 The European Society of Cardiology.