7.6 THE DIFFERENCE IN GLUTATHIONE PEROXIDASE ACTIVITY ON ARTERIES OF A BI-ETHNIC POPULATION: THE SABPA STUDY

Abstract

Background and objectives: From the literature it is evident that increased oxidative stress is integral in the development of cardiovascular disease. We therefore aimed to compare glutathione peroxidase (GPx) and glutathione reductase (GR) activity between black and white Africans, and to investigate whether the activity of these enzymes are linked with cardiovascular function. Methods: This sub-study was embedded in the Sympathetic Activity and Ambulatory Blood Pressure in Africans (SABPA) study, included 188 black and 203 white teachers from the Dr Kenneth Kuanda Education District in the North West Province of South Africa. Ambulatory blood pressure (BP) and carotid dorsalis pedis pulse wave velocity (cdPWV) were measured. Biochemical analyses included GPx and GR enzyme activity, serum peroxide and total glutathione levels. Results: The blacks presented with an unfavourable cardiovascular profile, with systolic- and diastolic BP, pulse pressure and cdPWV being significantly higher (p≤0.006) when compared to their white counterparts. The black group also displayed significantly higher levels of serum peroxides (p=0.049) with concomitant lower GPx activity (p=0.01), while their total glutathione levels (p<0.001) and GR activity (p<0.001) were significantly higher. In single regression analysis, an inverse relationship between GPx activity and cdPWV (r=−0.16 p=0.024) were indicated, only in the white group. The link between higher GPx activity and lower cdPWV was confirmed to be independent in multiple regression analyses (R2= 0.39 β=−0.18 p=0.005), while it was absent in the black group. Conclusion: An inverse relationship between GPx activity and cdPWV was encountered, suggesting a protective role of higher GPx activity against arterial stiffening in the white group.