African American race is an independent risk factor for enhanced oxidative stress and inflammation. We sought to examine whether oxidative stress and inflammatory markers that are typically measured in human also differ by race in cell culture. We compared levels between African American and Caucasian young adults and then separately in human umbilical vein endothelial cells (HUVECs) from both races. We found heightened oxidative stress and inflammation in the African Americans both in vitro and in vivo. African American HUVECs showed higher nitric oxide (NO) levels (10.8±0.4 vs 8.8±0.7umol/L/mg, P=0.03), IL-6 levels (61.7±4.2 vs 23.9±9.0pg/mg, P=0.02), and lower superoxide dismutase activity (15.6±3.3 vs. 25.4±2.8U/mg, P=0.04), and also higher protein expression (p<0.05) of NADPH oxidase subunit p47phox, isoforms NOX2 and NOX4, endothelial nitric oxide synthase, inducible NOS, as well as IL-6. African American adults had higher plasma protein carbonyls (1.1±0.1 vs 0.8±0.1nmol/mg, P=0.01) and antioxidant capacity (2.3±0.2 vs 1.1±0.3mM, P=0.01). This preliminary translational data demonstrates a racial difference in HUVECs much like that in humans, but should be interpreted with caution given its preliminary nature. It is known that racial differences exist in how humans respond to development and progression of disease, therefore these data suggest that ethnicity of cell model may be important to consider with in vitro clinical research.

Aims

African-Americans, in particular women, exhibit disproportionate levels of hypertension, inflammation, and oxidative stress compared to other ethnic groups. The relationship between prehypertension, renal function, inflammation, and oxidative stress was examined.

Methods

Twenty-eight African-American women (53.5 ± 1.1 years) followed an AHA diet and then underwent 24-hour ambulatory BP (ABP) monitoring. Urinary albumin (uAlb), serum and urinary creatinine, glomerular filtration rate (GFR), 24-hour urinary Na+ excretion, plasma superoxide dismutase, total antioxidant capacity (TAC), urinary (uNOx) and plasma (pNOx) nitric oxide levels, and high-sensitivity C-reactive protein (hsCRP) were measured.

Results

When the group was divided by average 24-hour ABP into optimal and nonoptimal groups, a significant difference existed between the groups for uNOx (p = 0.001; nonoptimal: 933.5 ± 140.4, optimal: 425.0 ± 52.6 μmol/gCr), and for hsCRP (p = 0.018, nonoptimal: 3.9 ± 0.7, optimal: 1.9 ± 0.6 mg/l). Significant inverse relationships existed between hsCRP and uNOx and between uAlb and pNOx in the non-optimal group, between GFR and pNOx in the entire group, and positive association existed between TAC and uNOx in the optimal group.

Conclusions

These results suggest that in African-American women as BP levels rise toward hypertension, the NO/NOS balance may be associated with renal function, and may have implications for CV risk based on their hsCRP levels.

Background

High blood pressure (BP) levels in African Americans elicit vascular inflammation resulting in vascular remodeling. BP variability (BPV) correlates with target organ damage. We aimed to investigate the relationship between inflammatory markers and BPV in African Americans.

Methodology

36 African Americans underwent 24-hr ambulatory BP monitoring (ABPM). BPV was calculated using the average real variability (ARV) index. Fasting blood samples were assayed for high sensitivity C-reactive protein (hs-CRP), tumor necrosis factor-alpha (TNF-α) and white blood cell (WBC) count.

Results

Significant association between hs-CRP and 24-hr systolic variability (r = 0.50; p = 0.012) and awake systolic variability (r = 0.45; p =0.02) was identified after adjusting for age, BMI and 24-hr mean BP. ABPM variables were compared between the hs-CRP tertile groups. In Post-hoc analysis, there was a significant difference in 24-hr and awake periods for both systolic and diastolic variability among the groups. TNF-α and WBC count showed no associations with ABPM variables.

Conclusion

hs-CRP is associated with systolic variability and higher levels of hs-CRP are related with greater BPV. Higher inflammatory status influences wider fluctuations in systolic BP which in turn could facilitate early progression to target organ damage independent of absolute BP levelsin African Americans.

African Americans have disproportionate levels of cardiovascular disease and oxidative stress. The purpose of our study was to examine racial differences between African American and Caucasian adults in time-course oxidative stress responses to a treadmill test. After a 12-hr fast, 18 participants (9 of each ethnic group; 21 ± 0.4 yrs) completed a submaximal treadmill test and underwent serial blood draws: Pre, Post (within 2 min), 30, 60, and 120 min after exercise. At each time-point, superoxide dismutase (SOD, U/mL), total antioxidant capacity (TAC, mM), protein carbonyls (PC, nmol/mg), and thiobarbituric acid-reactive substance (TBARs, μmol/L) were measured. We found no difference between groups for blood pressure, BMI, or exercise capacity (as measured by volume of oxygen consumed, VO2 max). African Americans had significantly (p < 0.05) higher SOD (Pre: 5.45 ± 0.4 vs. 3.69 ± 0.69; 60 min: 8.99 ± 0.7 vs. 4.23 ± 0.6; 120 min: 9.69 ± 1.6 vs. 3.52 ± 0.7), TAC (Pre: 2.31 ± 0.25 vs. 1.16 ± 0.3; Post: 2.39 ± 0.2 vs. 1.34 ± 0.2; 30 min: 2.29 ± 0.2 vs. 1.09 ± 0.2), and PC (Pre: 1.09 ± 0.1 vs. 0.82 ± 0.1; Post: 1.14 ± 0.1 vs. 0.81 ± 0.1; 30 min: 1.13 ± 0.1 vs. 0.85 ± 0.1; 60 min: 1.06 ± 0.1 vs. 0.81 ± 0.05), but not TBARs. Between groups, only SOD exhibited a different time-course response: levels for African Americans rose steadily throughout the 120 min, while levels for Caucasians peaked at 30 min and by 120 min had returned to pre-exercise levels. Race had a greater effect on oxidative stress responses than submaximal exercise did. African Americans had significantly higher TAC, SOD, and PC levels compared to Caucasians.

Objective

To examine the interaction of oxidative stress biomarkers with age, and also factors that influence oxidative stress such as body mass index (BMI) and fitness in a population of individuals with established higher risk of cardiovascular disease, African Americans.

Methods

Blood samples were obtained from healthy college-age and middle-age to older African Americans. Participants underwent a graded exercise test. Superoxide dismutase (SOD) activity, total antioxidant capacity and thiobarbituric acid reactive substances (TBARS) levels were measured.

Results

TBARS levels were significantly (P=.001) lower in young participants relative to middle-age to older participants. SOD activity was significantly (P=.001) lower in middle-age to older participants with low fitness relative to participants with normal fitness, and lower (P=.04) in middle-age to older participants that were overweight relative to normal weight participants.

Discussion

In a healthy middle-age to older population of African Americans, BMI and fitness are crucial for maintaining a healthy endothelium.

We investigated the relationship between renal function, blood pressure variability (BPV), and nitric oxide (NO) in a group of African Americans with normal or mildly impaired renal function. 24-hour ambulatory blood pressure monitoring was performed, NO measured, and glomerular filtration rate (GFR) calculated in 38 African Americans. Participants were categorized as having normal (GFR > 90 mL/min per 1.73 m2) or mildly impaired (GFR 60–89 mL/min per 1.73 m2) renal function. Diastolic BPV was significantly lower in the mildly impaired renal function group. Regression analyses revealed a significant positive association between GFR and diastolic BPV for the entire study group. Plasma NO levels were significantly higher in the mildly impaired renal function group and negatively correlated with diastolic BPV. In conclusion, diastolic BPV was reduced in African Americans with mildly impaired renal function, which may be the result of increased NO production. These results conflict with previous findings in diseased and nonblack populations and could provide rationale for studying BPV early in the disease state when BP-buffering mechanisms are still preserved.

Objective

The purpose of this study was to examine the effects of aerobic exercise training (AEXT) on dipping status in pre-hypertensive and stage-1 hypertensive individuals. A secondary purpose was to evaluate whether AEXT alters oxidative stress and endothelial biomarkers correlated to dipping status.

Methods

Twenty-three subjects underwent 24-h ambulatory blood pressure monitoring at baseline and after 6 months of AEXT. AEXT consisted of training at 70% VO2max 3 days/week for 6 months. Total cholesterol, high-density lipoprotein-cholesterol, low-density lipoprotein (LDL)-cholesterol, oxidized LDL (ox-LDL), triglycerides, urinary and plasma nitric oxide end-products, superoxide dismutase and 8-iso-PGF2α were measured before and after AEXT. Statistically, ANOVA and linear regression were used.

Results

Before and after AEXT, there were no significant differences between dippers and non-dippers in any of the biomarkers except for total cholesterol following AEXT. In a sub-analysis following AEXT, 14 subjects retained their original dipping status, five subjects changed from dippers to non-dippers and four subjects changed from non-dippers to dippers. Significant differences existed between these groups in changes in total and LDL-cholesterol, ox-LDL, 8-iso-PGF2α and % Dip.

Conclusions

Changes in cholesterol levels but not oxidative stress or endothelial biomarkers were related to changes in BP variables following AEXT in dippers and non-dippers.