title: Antioxidant enzyme activity is associated with blood pressure and carotid intima media thickness in black men and women: The SABPA study.
abstract: In the urbanized black population of South Africa, oxidative stress may play a crucial role in the development of hypertension. Since oxidative stress may result from impaired antioxidant capacity we aimed to investigate antioxidant enzyme activity as well as its associations with vascular function and structure in a bi-ethnic population. Participants included 409 subjects almost equally stratified by ethnicity and sex. Blood pressure and carotid intima media thickness (cIMT) were measured and glutathione peroxidase (GPx), glutathione reductase (GR), superoxide dismutase (SOD) and catalase (CAT) enzyme activities were determined. GR activity was significantly higher in black men (7.71 nmol/min/ml vs 2.23 nmol/min/ml) and women (6.46 nmol/min/ml vs 2.86 nmol/min/ml) (p < 0.001) when compared to their white counterparts. In black women, GPx activity was significantly lower (p < 0.001) when compared to white women (31.9 nmol/min/ml vs 37.1 nmol/min/ml). In black men, cIMT was positively and independently associated with GR activity (R(2) = 0.30; β = 0.18; p = 0.048). In black women, systolic blood pressure (R(2) = 0.21; β = -0.24; p = 0.014), diastolic blood pressure (R(2) = 0.11; β = -0.20; p = 0.044) and mean arterial pressure (R(2) = 0.20; β = -0.31; p = 0.002) were inversely associated with GPx activity. No associations were found in the white groups. The positive association between GR activity and cIMT in black men may be the result of a compensatory response to prevent arterial remodelling. The inverse association between GPx activity and blood pressure in black women may indicate a role for decreased GPx activity in hypertension development in this population.
authors.affiliation: Hypertension in Africa Research Team (HART), North-West University, Private Bag X6001, Potchefstroom, 2520, South Africa.
authors.forename: Caitlynd
authors.initials: C
authors.lastname: van Zyl
authors.affiliation: Hypertension in Africa Research Team (HART), North-West University, Private Bag X6001, Potchefstroom, 2520, South Africa; MRC Research Unit for Hypertension and Cardiovascular Disease, North-West University, South Africa.
authors.forename: Hugo W
authors.initials: HW
authors.lastname: Huisman
authors.affiliation: Hypertension in Africa Research Team (HART), North-West University, Private Bag X6001, Potchefstroom, 2520, South Africa. Electronic address: Carina.Mels@nwu.ac.za.
authors.forename: Catharina M C
authors.initials: CM
authors.lastname: Mels
mesh_terms: D000328:Adult; D001741:Black or African American; D000368:Aged; D000886:Anthropometry; D000975:Antioxidants / Q000378:metabolism*; D002318:Cardiovascular Diseases; D002339:Carotid Arteries / Q000378:metabolism*; D059168:Carotid Intima-Media Thickness; D003430:Cross-Sectional Studies; D005260:Female; D005979:Glutathione Peroxidase / Q000378:metabolism; D005980:Glutathione Reductase / Q000378:metabolism; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D018384:Oxidative Stress; D012044:Regression Analysis; D066253:Vascular Remodeling; D055815:Young Adult
chemical_list: D000975:Antioxidants; D005979:Glutathione Peroxidase; D005980:Glutathione Reductase
keywords: Antioxidant enzyme activity; Blood pressure; Carotid intima media thickness; Ethnicity; Glutathione peroxidase; Glutathione reductase; Oxidative stress