The relation of blood pressure and carotid intima-media thickness with the glutathione cycle in a young bi-ethnic population: the African-PREDICT study

Abstract

Oxidative stress has been implicated in the development of hypertension, arterial stiffness and atherosclerosis. Optimal functioning of the enzymatic antioxidant system is central to prevent increased oxidative stress and its consequences. We aimed to investigate the relationships of ambulatory blood pressure and carotid intima-media thickness with enzyme activities of the glutathione cycle in young, healthy black and white South Africans. This study included 396 participants (black men (N = 89), white men (N = 78), black women (N = 105) and white women (N = 124)) of the African-PREDICT study aged 20-30 years. Ambulatory blood pressure and carotid intima-media thickness were measured, while glutathione peroxidase and glutathione reductase activity were analyzed in blood samples. In black men, ambulatory pulse pressure was negatively associated with glutathione peroxidase activity (R2 = 0.19; β = -0.25; p = 0.026). Black and white women displayed positive associations of ambulatory systolic blood pressure and ambulatory mean arterial pressure with glutathione reductase activity while white men displayed a positive association of ambulatory pulse pressure with glutathione reductase activity. The lower glutathione peroxidase activity and total antioxidant status, the higher reactive oxygen species as well as the negative association between ambulatory pulse pressure and glutathione peroxidase activity in the black men suggest that oxidative stress is associated with early vascular changes in this group. In the other three groups, the positive associations of blood pressure with glutathione reductase activity suggest a possible role for adequate glutathione reductase activity in preventing or delaying the development of hypertension