Cardiovascular function is not associated with creatine kinase activity in a black African population: The SABPA study.

BACKGROUND: Higher creatine kinase (CK) activity is associated with the development of cardiovascular disease in black African populations. We compared CK activity and investigated associations of blood pressure with CK activity in black and white men as well as black and white women. METHODS: Ambulatory blood pressure, total peripheral resistance and pulse wave velocity of 197 black and 208 white participants were determined and serum CK activity was measured. RESULTS: Blood pressure and pulse wave velocity were higher in black men and women (all p < 0.001) when compared to their white counterparts. CK activity only varied between black and white women (75.9 U/l vs 62.8 U/l, p = 0.009), even after adjusting for age, body mass index and physical activity. Despite the worse cardiovascular profile of black men and women, and the higher CK activity in the black women, we were unable to link blood pressure, pulse wave velocity or total peripheral resistance with CK activity, in the black African population. In white men, total peripheral resistance was associated with CK activity (R (2) = 0.32; ß = 0.25; p = 0.009), whereas systolic blood pressure (R (2) = 0.46; ß = 0.17; p = 0.03) and pulse pressure (R (2) = 0.31; ß = 0.21; p = 0.01) were associated with CK activity in white women. CONCLUSIONS: The lack of associations in the black African population suggests that the link between a worse cardiovascular profile and CK activity may be overshadowed by other contributing factors. Whereas, the established link between cardiovascular function and CK activity in the white groups may be the result of enhanced smooth muscle cell contractility and/or attenuated nitric oxide synthesis capacity.

Antioxidant enzyme activity is associated with blood pressure and carotid intima media thickness in black men and women: The SABPA study.

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; ß = 0.18; p = 0.048). In black women, systolic blood pressure (R(2) = 0.21; ß = -0.24; p = 0.014), diastolic blood pressure (R(2) = 0.11; ß = -0.20; p = 0.044) and mean arterial pressure (R(2) = 0.20; ß = -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.