Changes in serum concentration of antioxidants following treadmill exercise testing in patients with suspected ischaemic heart disease.

Twenty-four subjects with suspected ischaemic heart disease underwent a treadmill exercise stress test (TEST). Nine individuals developed ischaemia as defined by standard criteria. Total plasma antioxidant status (TPAS), and serum concentrations of vitamin E were measured pre-TEST, and 0, 1, 2, 4, 8 and 24 h following the treadmill test. Mean serum vitamin E concentrations fell by 33% in the group as a whole (from 9.53 +/- 0.92 mg/L pre-TEST to 6.39 +/- 1.06 mg/L immediately post stress test, P < 0.02) and rose to baseline over the subsequent 24 h. The levels of serum vitamin E fell by 34% in the group of patients who had a positive TEST, and 32% in those who did not develop ischaemia during the TEST. Serum cholesterol concentrations also fell significantly during the TEST. In the total group serum cholesterol fell by 6.5% (P = 0.0052), and in the subgroup who were positive for ischaemia the fall in serum cholesterol was 10.3% (P = 0.004). The reduction in serum cholesterol was 4.1% in the subgroup who did not develop ischaemia (P > 0.05). Mean total plasma antioxidant status showed no significant temporal change for the group as a whole, although there was a nonsignificant decrease immediately post-TEST in the ischaemic group and a slight rise at 8 h in the group negative for ischaemia.