Nitric oxide synthesis capacity, ambulatory blood pressure and end organ damage in a black and white population: the SABPA study

Abstract

Nitric oxide (NO) synthesis capacity is determined by the availability of substrate(s) such as L-arginine and the influence of nitric oxide synthase (NOS) inhibitors, asymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA). These factors may be important in black South Africans with a very high prevalence of hypertension. We compared ambulatory blood pressure (BP), markers of end organ damage and NO synthesis capacity markers [L-arginine, L-homoarginine, L-citrulline, L-arginine:ADMA, ADMA, SDMA and dimethylarginine (DMA)], between black and white teachers (n = 390). Associations of nighttime BP and markers of end organ damage with NO synthesis capacity markers were also investigated. Although black men and women had higher BP and albumin-to-creatinine ratio (ACR) (all p < 0.001), they also had higher L-arginine, L-homoarginine, L-arginine:ADMA and lower SDMA and DMA levels (all p < 0.05). Only in white men ADMA concentrations associated positively with nighttime systolic blood pressure (R (2) = 0.20, β = 0.26, p = 0.009), nighttime diastolic blood pressure (R (2) = 0.23, β = 0.27, p = 0.007), carotid intima media thickness (cIMT) (R (2) = 0.36, β = 0.22, p = 0.008) and ACR (R (2) = 0.14, β = 0.32, p = 0.001). Our findings suggest that despite an adverse cardiovascular profile in blacks, their NO synthesis capacity profile seems favourable, and that other factors, such as NO inactivation, may prove to be more important.

Arginine-Nitric Oxide Metabolites and Cardiac Dysfunction in Patients With Breast Cancer

“…Higher baseline levels of specific metabolites were associated with older age, hypertension, and higher BMI, which is consistent with previous studies showing these metabolites as general markers of cardiovascular disease risk (18,20,27). African Americans had lower baseline levels of ADMA and SDMA, which is consistent with previously described ethnic distributions that had demonstrated higher redox status in this population (28–30). However, African Americans also had a slightly greater degree of cardiovascular comorbidities—including more hypertension (52% vs. 20%), diabetes (16% vs. 4%), and larger BMI (median 31 vs. 25)—at baseline as compared to Caucasians.…”

An Ethnic Comparison of Arginine Dimethylation and Cardiometabolic Factors in Healthy Black and White Youth: The ASOS and African-PREDICT Studies

“…None of the PADiMe indices were found to be associated with BP in the ASOS and African-PREDICT studies, which included healthy participants. The findings of the present study support the observations of the lower circulating ADMA and SDMA concentrations in black subjects measured in the SABPA study [44]. Low urinary excretion of ADMA is a cardiovascular risk factor in white adults [45,46].…”

“…In previous bi-ethnic studies, serum ADMA and SDMA concentrations were found not to differ between black and white men [43]. In the SABPA (Sympathetic Activity and Ambulatory Blood Pressure in Africans) study, black men and women had higher BP and albumin-to-creatinine ratios, higher plasma concentrations of the NOS substrate Arg, and even lower plasma concentrations of ADMA and SDMA, the NOS inhibitors, compared to white men [28,44].…”

Hypertension and ethnicity

“…Unique genetic polymorphisms of MYH9 and apolipoprotein L1 genes are associated with the development of kidney disease in blacks [26,27]. Detailed studies of the Genetic Risk Assessment of Heart Failure in African-Americans registries are currently shedding light on the genetic frequency of aldosterone synthase (CYP11B2) and endothelial constitutive nitric oxide synthase within both black and white populations [17,[31][32][33]. More specifically, a common polymorphism identified within the CYP11B2 gene has been linked to HTN by promoting higher than normal levels of aldosterone synthase activity.…”