Background:Nitric oxide (NO) plays a pivotal role in the pathophysiology of coronary heart disease (CHD). Low plasma concentrations of NO metabolites (nitrite and nitrate), the stable oxidation products of NO have been reported in patients with CHD but this is controversial. Plasma nitrite and nitrate concentrations during symptomatic myocardial ischaemia and in response to exercise in subjects with CHD have not been studied. We therefore measured plasma nitrite and nitrate concentrations in subjects before and after an exercise tolerance test (ETT).Material/Methods:Plasma nitrite and nitrate concentrations were measured before and after an ETT in 24 subjects with symptomatic exercise-induced myocardial ischaemia (positive ETT) and in 27 subjects without exercise-induced myocardial ischaemia (negative ETT).Results:Plasma nitrate concentrations were higher (p

Keywords: Case-Control Studies, Exercise Test, Myocardial Ischemia - blood, Myocardial Ischemia - metabolism, Nitrates - blood, Nitric Oxide - metabolism, Nitrites - blood