Antioxidant enzyme activities and total nitrite/nitrate levels in the collar model. Effect of nicardipine

There is a large body of literature describing the causative role of oxidat ive stress mediated by increased levels of reactive oxygen species in the p athogenesis of cardiovascular disease such as atherosclerosis, hypertension , and restenosis after angioplasty. The positioning of a soft silicone coll ar around the rabbit carotid artery elicits intimal thickening. The finding s from recent studies demonstrated that both intimal thickening and atheros clerosis lead to synthesis of inducible nitric oxide synthase, resulting in abundant amounts of nitric oxide. We investigated the effects of collaring and nicardipine treatment on the activities of antioxidant enzymes, supero xide dismutase and catalase, and total nitrite/nitrate levels, stable produ cts of nitric oxide. Placing the collar increased the total nitrite/nitrate levels and decreased superoxide dismutase activity in collared arteries. T reatment with nicardipine (20 mg/kg/day, s.c.) prevented enhanced nitric ox ide degradation without affecting superoxide dismutase and catalase activit ies. Our results suggest that enhanced nitric oxide production and superoxi de anion are generated in response to the collaring, resulting in oxidative stress within the segment in this model.