Investigation of the correlation between oxidative stress and hypertension : the SABPA study

Abstract

Recently, an alarmingly high prevalence of hypertension is seen in urbanised black South African communities, compared to their Caucasian counterparts. Therefore a study was organised to assess these lifestyle changes and incidence of hypertension with regards to the individual's reaction to elevated stress levels. This study was dubbed the Sympathetic activity and Ambulatory Blood Pressure in Africans (SABPA) study. The present study (as part of the SABPA study) was initiated to investigate whether this high blood pressure had any influence on a person's oxidative stress profile. Therefore, several tests were carried out on samples from the 200 SABPA participants. The tests consisted of oxidative stress assays, including ROS levels, FRAP values and the GSH concentration in blood. A newly developed PCR and RFLP approach was also followed to screen the samples for a specific single nucleotide polymorphism (SNP) in the tyrosine hydroxylase (TH) gene. This enzyme takes part in catecholamine biosynthesis, which is a pathway activated in times of stress. Along with the assays performed, the daytime ambulatory blood pressure values (08h00 to 18h00) were also obtained. After analyses were performed, several statistical methods were carried out on the data and results were graphically represented. Preliminary results showed gender differences with regards to oxidative stress parameters and thus all subsequent data was divided for the two genders. Results from the male group in this study support the hypothesised connection between oxidative stress and hypertension, as the ROS levels were higher in hypertensive males than in normotensive males. However, the hypothesised connection between the TH C-824T base change and high blood pressure could not be proven. It was concluded that there is indeed a positive correlation between oxidative stress and hypertension, as hypothesised.