Angiotensin II, which is also thought to play a key role in atherosclerosis, has recently been shown to have pro-oxidant effects, by increasing superoxide (•O₂ ⁻) production in human arteries.1 Oxidative stress, a state of excessive free radical activity which is associated with reduced bioavailable nitric oxide (NO), may be evident in patients with coronary heart disease (CHD).2 Lately ACE inhibitors have been shown to reduce cardiovascular morbidity and mortality in patients at high risk of CHD.3 The aim of the present study was to determine, which, if any, risk factors and drug treatments were associated with altered free radical concentrations in the arteries of CHD patients undergoing coronary artery bypass grafting (CABG).

Seventy nine consecutive patients who were undergoing CABG were prospectively included in this study. Patient characteristics were determined by review of case records. A history of current cigarette smoking, hypertension (defined as either current antihypertensive treatment or a blood pressure > 140/90 mm Hg), diabetes mellitus, and hypercholesterolaemia (plasma cholesterol > 5.5 mmol/l) were considered as risk factors for CHD.

Distal segments of left internal mammary artery which were obtained at the time of CABG were taken to the …