['Recently, many antioxidants have been tested in cardiovascular disease. The effect of antioxidants on alleviation of coronary vasospasm, however, remains unclear. We investigated whether chronic administration of ascorbic acid and glutathione prevents coronary vasospasm in pigs.', 'Balloon-induced endothelial injury in the left anterior descending coronary artery was performed every 2 weeks until 6 weeks (0, 2, 4, 6 weeks). Ten micrograms per kilogram serotonin-induced vasoconstriction was assessed before each endothelial injury and at eighth week by coronary angiography.', 'In endothelial injury without antioxidant group (ED group, n=12), serotonin-induced left anterior descending coronary artery vasoconstriction was augmented from 7+/-4% (0 week) to 88+/-8% (8th week, P<0.01) with electrocardiogram-ST elevation, and an increase of cyclooxygenase-2 expression and a decrease of endothelial nitric oxide synthase expression was observed at the spasm portion removed from the endothelial denuded site. In the endothelial injury group with oral administration of ascorbic acid 3 g/day and glutathione 1 g/day after the first endothelial injury (ASC+GSH group, n=12), serotonin-induced vasoconstriction was suppressed (8th week, 60+/-6%, P<0.01 vs. ED group) and endothelial nitric oxide synthase expression was fairly well maintained. Intimal thickening was observed at the left anterior descending artery spasm portion in the endothelial injury without antioxidant group but not at the corresponding portion in the ASC+GSH group.'] Is antioxidant a useful supportive agent for the treatment of coronary vasospasm with endothelial dysfunction in pig?