Consistent reports indicate that hypertension is a particularly common finding in black populations. Hypertension occurs at younger ages and is often more severe in terms of blood pressure levels and organ damage than in whites, resulting in a higher incidence of cardiovascular disease and mortality. This review provides an outline of recent advances in the pathophysiological understanding of blood pressure elevation and the consequences thereof in black populations in Africa. This is set against the backdrop of populations undergoing demanding and rapid demographic transition, where infection with the human immunodeficiency virus predominates, and where under and over-nutrition coexist. Collectively, recent findings from Africa illustrate an increased lifetime risk to hypertension from foetal life onwards. From young ages black populations display early endothelial dysfunction, increased vascular tone and reactivity, microvascular structural adaptions as well as increased aortic stiffness resulting in elevated central and brachial blood pressures during the day and night, when compared to whites. Together with knowledge on the contributions of sympathetic activation and abnormal renal sodium handling, these pathophysiological adaptations result in subclinical and clinical organ damage at younger ages. This overall enhanced understanding on the determinants of blood pressure elevation in blacks encourages (a) novel approaches to assess and manage hypertension in Africa better, (b) further scientific discovery to develop more effective prevention and treatment strategies and (c) policymakers and health advocates to collectively contribute in creating health-promoting environments in Africa.

Systemic and organ adaptation in hypertensionMethods: We examined 103 obese men (body mass index ≥30.0kg/m 2 ).All men were generally healthy and medication-free.We measured BP using 24-hr ambulatory BP (ABP) recordings.We determined left atrial size and LVM using standard echocardiography, and we measured fasting serum concentrations of midregional proatrial natriuretic peptide (MR-proANP) and B-type natriuretic peptide (BNP).ANOVA was used to test for linear trend across quartiles of mean 24-hr systolic ABP. Results:The table shows the distribution of selected variables according to quartiles of mean 24-hr systolic ABP.Significant P values for trend were determined between 24-hr systolic ABP and left atrial size and LVM.Despite substantial differences in 24-hr systolic ABP across the systolic ABP quartiles and evidence of pressure-induced greater left atrial size and higher LVM, serum MR-proANP and BNP concentrations did not increase with higher 24-hr systolic ABP.Conclusions: Serum MR-proANP and BNP do not increase with higher systolic ABP in obese men despite evidence of greater left atrial size and higher LVM.

Objective: The objective of this study was to make use of a quantitative and qualitative approach comparing the systemic renin-angiotensin system (RAS) of hypertensive black and white African men by using RAS equilibrium analysis. Materials and methods: This sub-study involved 23 black (n = 15) and white (n = 8) hypertensive men aged 39.5–41 years, living in the North West Province of South Africa. The RAS-Fingerprinting was determined with LC-MS/MS quantification of angiotensin peptides. Blood pressure and other variables were determined with known methods. Results: The main finding of this study was the significant lower Ang I (<5.0 and 45.1 pg/ml; p = 0.005) and Ang II (15.6 and 123.9 pg/ml; p ⩽ 0.001) encountered in the hypertensive black African men compared to their white counterparts. Levels of Ang 1-5 (downstream metabolite of Ang 1-7) (1.8 and 3.0 pg/ml), were detected in black and white hypertensive men, respectively. Conclusions: The observed differences between circulating RAS components, which are reflected via equilibrium angiotensin levels, point to a distinctive molecular regulation of the RAAS in the two study cohorts. The increased peripheral resistance observed in hypertensive black individuals might take over a dominant role in control of blood pressure in this study population. A novel highly sensitive LC-MS/MS method resolved the issue of peptide recovery variations during sample preparation by using internal standards for each individual angiotensin metabolite.

Objectives: Carotid-femoral pulse wave velocity (PWV) is a surrogate marker of atherosclerosis and predictive of cardiovascular events, morbidity and mortality. HIV is associated with hypertension, dyslipidaemia and endothelial dysfunction resulting in increased stiffness. Studies comparing arterial stiffness in HIV infected to HIV-free individuals are scarce, especially in South Africa one of the countries most affected by HIV and with a high prevalence of hypertension. We compared arterial stiffness between HIV infected and HIV-free black individuals.

Objective: The current study aimed to determine the prevalence of masked hypertension (i.e. normotensive office blood pressure [BP] and hypertensive ambulatory BP) in a young, bi-ethnic South African population who were recruited on to the AFRICAN-PREDICT study based on normotensive office BP readings. Design and method: The first baseline phase of the AFRICAN-PREDICT study recruited 352 participants from within the North-West province, South Africa (54% white, 40% male). Study eligibility criteria were; 20 to 30 years of age, normal office BP, not on BP medication, black or white South African, HIV-negative, and apparently healthy. Measurements included 24hour ambulatory BP monitoring (ABPM) (Cardio-Xplore), aortic pulse wave velocity (aPWV) and augmentation index (AIx) (SphygmoCor-XCEL), peripheral BP (DINAMAP) and the Godin exercise questionnaire. Further to this, fasted venous blood samples were collected for biochemical analyses. Results: By office and ABPM BP, n = 290 (82%) were normotensive (NT), and n = 62 (18%) had masked hypertension (MHT). The MHT group had significantly higher clinic and ABPM (24hour, day and night) BPs, aPWV, I-CAM, MCP-1, and insulin levels, compared to NT. There were no differences in cotinine or exercise levels.Conclusions: These data, obtained from a cohort recruited on the basis of their normotensive office BP, highlight the high prevalence of masked hypertension among young South Africans. Masked hypertension further demonstrated increased CV risk via unfavourably increased haemodynamic and biochemical markers. This group would have been missed without measurement of ambulatory BP and therefore unaware of the lifestyle or pharmaceutical changes required. As well as the important public health message, these data highlight the importance of using sensitive markers of BP in research if recruiting based on BP status.

BackgroundElevated inflammatory markers such as C-reactive protein (CRP) and interleukin-6 (IL-6) are well-known risk factors for cardiovascular mortality. The less familiar marker, soluble urokinase plasminogen activator receptor (suPAR), is known to predict cancer, infections and all-cause mortality. We determined whether suPAR, CRP and IL-6 are predictive of both all-cause and cardiovascular mortality in a black population, highly burdened by cardiovascular disease and HIV infection.MethodsWe included 1425 black South Africans, of which 208 died within five years after baseline data collection. EDTA plasma biomarker levels were determined, while all-cause and cardiovascular mortality were used as endpoints.ResultsAt baseline suPAR, CRP and IL-6 were higher in non-survivors than in survivors (P<0.001). SuPAR (HR 1.27, 95% CI 1.09–1.48), IL-6 (HR 1.49, 95% CI 1.24–1.78) and CRP (HR 1.39, 95% CI 1.17–1.65) predicted all-cause mortality, while only suPAR (HR 1.40, 95% CI 1.04–1.87) and IL-6 (HR 1.61, 95% CI 1.10–2.35) predicted cardiovascular mortality. The prognostic value of suPAR was independent of IL-6 and CRP (P≤0.015).ConclusionSuPAR predicted both all-cause and cardiovascular mortality, independent of traditional risk factors, HIV and other inflammatory markers, underlining the prognostic value of suPAR in a black population.

Objective:The current study aimed to determine the prevalence of masked hypertension (i.e. normotensive office blood pressure [BP] and hypertensive ambulatory BP) in a young, bi-ethnic South African population who were recruited on to the AFRICAN-PREDICT study based on normotensive office BP reading

Large epidemiological studies confirm that brachial BP is positively related to red blood cell (RBC) count, hematocrit and hemoglobin. Despite several mechanisms being put forward, there are not yet a clear understanding on the interactions between erythrocytes and the arterial wall. Recent studies suggest BP lowering functions of RBCs by demonstrating that erythrocytes carry endothelial NO synthase, and that RBCs release ATP that triggers NO release. We assessed how central and brachial pressures, as well as arterial stiffness relate to RBC indices in healthy conditions within a young normotensive bi-ethnic population. We included 328 black and white men and women aged 20–30 yrs. We performed full blood counts and assessed brachial (bSBP, DBP, Dinamap Procare 100) and central pressure (cSBP) and pulse wave velocity (PWV; Sphygmocor XCEL). Black participants (N=121) aged 25.2 yrs had higher bSBP (117/80 mmHg vs 113/77 mmHg) and cSBP (110 vs 105 mmHg) than white participants (N=207) aged 26.1 (all p≤0.001), with similar RBC counts (p=0.40). In multivariable-adjusted regression analyses cSBP related positively to RBC count in both groups (black: β=0.24; p=0.045; white: β=0.24; p=0.006) - not seen for bSBP (black: β=0.09; p=0.36; white: β=0.03; p=0.68). Only the black group showed independent associations of DBP with RBC count and hematocrit (p≤0.002), whereas PWV did not relate to RBC indices in any group. We found that cSBP, but not bSBP, is positively associated with RBC count in a young normotensive bi-ethnic sample, suggesting that central haemodynamics may be more affected by increasing RBCs.