Cardiopulmonary exercise testing and its relation to oxidative stress in patients with hypertension

An increase in reactive oxygen species has been implicated in the pathologies of hypertension. This study was designed to evaluate antioxidant activity in hypertensive patients and to assess the relationship between oxidative stress and exercise tolerance in hypertensive patients with mild left ventricular diastolic dysfunction (LVDD). A total of 42 patients, aged 51±9 years, with a long history of hypertension and mild LVDD (mitral flow velocities-E/A <1, deceleration time of E >220 ms, and preserved ejection fraction-EF >50%), and 30 controls without cardiovascular disease, aged 50±7 years, underwent cardiopulmonary exercise testing (CPET). Peak oxygen uptake (peak VO(2)), oxygen pulse (VO(2)/heart rate (HR)) and ventilatory anaerobic threshold (VAT) were obtained during CPET. Antioxidant activity of superoxide dismutase (SOD) and glutathione peroxidase in the blood was measured before and after exercise. Reduced peak VO(2) (1715±426 vs. 2083±465 ml min(-1), P<0.001), VO(2)/HR (12.0±2.8 vs. 14.6±3.3 ml per beat, P<0.001) and percentage of peak VO(2) at VAT (55.5±15.8% vs. 64.5±14.7%, P=0.007) were observed in hypertensive patients, compared with controls. Antioxidant protection was significantly attenuated in hypertensive patients, compared with controls, before (945 vs. 1006, P=0.012) and after exercise (954 vs. 1051, P<0.001). The level of SOD before and after exercise was significantly associated with LVDD in hypertensive patients (P=0.012 and 0.02, respectively). In addition, the degree of LVDD before exercise (E/A) influenced the degree of exercise capability (peak VO(2)) (P=0.016). Asymptomatic hypertensive patients with mild LVDD had reduced cardiopulmonary capacity, accurately identified by CPET. The redox state in hypertensive patients was significantly related to LVDD and exercise tolerance. Attenuated antioxidant protection was associated with long-term hypertension.