EFFECT OF EXERCISE TESTING ON LIPID PEROXIDE LEVELS OF PLASMA AND ERYTHROCYTE-GHOSTS

This study was designed to detect whether the plasma level of lipid pe roxide and of erythrocyte ghost (EG) would be affected by treadmill ex ercise testing carried out by the modified Bruce method in patients wi th hypertension or hypercholesterolemia, A total of 27 patients were s tudied for changes in their ECG. On exercise testing, 10 patients resp onded positively and 17 negatively. Before testing, plasma levels of l ipid peroxide were 3.9 +/- 0.9 nmol/ml (mean +/- SE) in the positive g roup and 1.6 +/- O.4 nmol/ml in the negative group, a significant diff erence (p< 0.05). The lipid peroxide (LPO) level of the EG was 3.7 +/- 0.8 nmol/mg protein in the positive group and 3.2 +/- 0.7 nmol/mg pro tein in the negative group. Exercise testing tended to induce a rise i n the lipid peroxide values in the EG of the positive group (11.3 +/- 5.0 nmol/mg protein vs. 3.7 +/- 0.8 nmol/mg protein, p < 0.1). The fol d-increase in the level of erythrocyte membrane lipid peroxide was sig nificantly higher in the positive responders (2.3 +/- O.7 vs. 0.8 +/- O.1, p < 0.05). There was no significant change in the plasma level of lipid peroxide in either group. Other clinical parameters including b lood pressure, heart rate, obesity, smoking, medication, exercise inte nsity, and plasma lipid levels showed no differences between the posit ive and the negative responders. We conclude that the erythrocyte memb ranes of the positive responders to treadmill exercising are easily pe roxidized by various stimuli, which may contribute in part to the high plasma lipid peroxide level before testing. A stimulus such as treadm ill testing may accelerate the lipid peroxidation of the erythrocyte m embranes significantly and independently.