Plasma nitrotyrosine in reversible myocardial ischaemia.

BACKGROUND Nitric oxide (NO) plays a vital role in vascular homeostasis and in the pathophysiology of coronary heart disease. Its metabolites, nitrite and nitrate, have vasculoprotective properties, whereas peroxynitrite, an oxidant metabolite of NO, is cytotoxic and can aggravate myocardial damage during ischaemic reperfusion injury. Peroxynitrite nitrates free and protein bound tyrosine residues to produce nitrotyrosine. The measurement of nitrotyrosine provides an indirect estimation of plasma peroxynitrite concentrations. AIMS To measure plasma nitrotyrosine concentrations to see whether peroxynitrite could contribute to myocardial dysfunction during myocardial ischaemia induced by an exercise tolerance test (ETT). MATERIALS/METHODS Plasma free nitrotyrosine concentrations were compared before and after exercise in 29 subjects with a positive ETT and 34 subjects with a negative ETT. RESULTS Plasma nitrotyrosine concentrations were similar in patients with exercise induced myocardial ischaemia and controls. CONCLUSION Peroxynitrite does not contribute to the myocardial dysfunction in reversible myocardial ischaemia.