Evaluation of the antioxidant response in the plasma of healthy or hypertensive subjects after short-term exercise

Reactive oxygen species are produced during exercise. The antioxidants prevent or limit tissue damages by these species in physiological conditions. In particular, ascorbate and urate scavenge peroxynitrite, which can alter the function of many molecules, including the lecithin-cholesterol acyltransferase (LCAT) enzyme involved in reverse cholesterol transport. The aims of the present study were to compare the plasma antioxidant response to an ergometric test (ET) in hypertensive and healthy subjects, evaluate the exercise-dependent nitrosative stress in plasma, and assess whether the LCAT activity is altered by the exercise. Plasma samples, prepared before and after ET from hypertensive or healthy volunteers, were analysed for their levels of ascorbate, urate, alpha-tocopherol, retinol, nitrotyrosine, and LCAT activity. The alpha-tocopherol and retinol levels did not significantly change in both groups during exercise, while the ascorbate level changed displaying higher increase in controls (+38.8%) than in hypertensives (+17.2%). In these patients, during ET, the urate and nitrotyrosine levels changed more than in normotensives (+13.5 and +40.6% vs -3.1 and +25.2%, respectively). The antioxidants effectively prevented loss or reduction of LCAT activity, as it was similar in hypertensives and normotensives, and did not change after ET. The results demonstrate that exercise is associated with enhanced protein nitrosation, and suggest that the ascorbate or urate levels increase to limit oxidative damage