A cross-sectional analysis of 278 South African adults has found that the relationship between urinary dopamine, a hormone the kidneys release to help regulate blood pressure, and the thickness of the carotid artery wall depends on ethnicity. In White participants, higher urinary dopamine levels were independently associated with greater carotid intima-media thickness, a marker of preclinical atherosclerosis. In Black participants, the same artery wall measure was instead linked to homovanillic acid, a major metabolite of dopamine, suggesting that dopamine turnover rather than dopamine itself tracks vascular change in this group. The findings come from the Sympathetic Activity and Ambulatory Blood Pressure in Africans (SABPA) study and are published in Artery Research.
Urinary dopamine is produced by the kidneys from circulating L-DOPA and acts on dopamine receptors within the renal tubules. Its best-established roles are promoting natriuresis, the excretion of sodium in the urine, along with vasodilation and anti-inflammatory effects, all of which support fluid balance and blood pressure control. Because sodium handling, sympathetic nervous system activity and the renin-angiotensin-aldosterone system differ notably across populations, the research team hypothesised that the link between this renal hormone and arterial health might also differ. People of African descent, for example, typically show lower renin levels, higher vascular resistance and enhanced salt sensitivity, a distinctive hypertensive profile that could interact with dopamine signalling in ways not yet well characterised.
The SABPA study recruited Black and White educators aged 20 to 65 years from the North-West Province of South Africa between February 2008 and May 2009. Data collection took place in a well-controlled overnight facility, where participants consumed a standardised dinner before 22:00 containing defined amounts of calcium, potassium, magnesium, phosphates and protein, and then fasted overnight. This design controlled dietary intake and minimised the white-coat effect on blood pressure. After excluding participants with missing values for urinary dopamine, urine sodium, DOPAC, pulse wave velocity, reactive oxygen species, endothelin-1 or carotid intima-media thickness, 278 participants remained: 110 Black and 168 White adults.
An 8-hour morning urine sample was collected from each participant and analysed for creatinine, sodium, potassium, dopamine and its metabolites 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), the latter two determined by high-performance liquid chromatography. Urinary dopamine was corrected for urinary creatinine to standardise for urine volume. Blood samples drawn after 30 minutes of supine rest were used to measure serum reactive oxygen species, determined with a fluorescence reader using a derivatives-of-reactive-oxygen-metabolites assay, and endothelin-1, quantified by enzyme-linked immunosorbent assay. High-sensitivity C-reactive protein, HbA1c, lipids and other covariates were also measured, and kidney function was estimated with the CKD-EPI formula.
Vascular assessments combined structural and functional measures. Ambulatory blood pressure was monitored for 24 hours on a working day at 30-minute daytime and hourly night-time intervals, the gold-standard approach for blood pressure measurement outside the clinic. Pulse wave velocity, a measure of arterial stiffness, was recorded between the carotid and dorsalis-pedis arteries with a Complior system. Carotid intima-media thickness was obtained by high-resolution ultrasound of the left and right common carotid arteries, carotid bulb and internal carotid segments, with digitised images analysed by automated software on the far wall of the vessels. Values above 0.90 mm suggest target organ damage, while 0.6 to 0.7 mm is typically considered normal in healthy middle-aged individuals.
The baseline comparison revealed a markedly less favourable cardiovascular profile in the Black group. Systolic and diastolic blood pressure measures and carotid intima-media thickness were all higher in Black participants, and a larger share was hypertensive under 24-hour ambulatory criteria, 58.2 percent versus 39.9 percent, with more taking antihypertensive medication. Urinary dopamine levels themselves were comparable between the two groups, but the metabolites HVA and DOPAC were higher in Black participants, as were the sodium-to-potassium ratio, serum reactive oxygen species and C-reactive protein, all differences reaching statistical significance.
The correlation analyses then exposed the ethnic divergence. In White participants, urinary dopamine correlated inversely with reactive oxygen species in unadjusted analysis, but after adjustment for age, sex, body mass index and mean arterial pressure this inverse link disappeared while a positive correlation with carotid intima-media thickness emerged. In backward multiple regression models retaining covariates such as age, sex, C-reactive protein, cotinine, HbA1c, alcohol use, eGFR and the sodium-to-potassium ratio, the positive independent association between urinary dopamine and carotid intima-media thickness was confirmed in the White group, with a standardised beta of 0.166 and a p-value of 0.007. In the Black group, it was HVA rather than dopamine that showed a positive independent association with the same artery wall measure, with a beta of 0.10 and a p-value of 0.036. Across the total population, both DOPAC and HVA correlated positively with carotid intima-media thickness, and a similar HVA association was evident in the Black group. When the sample was stratified by sex, the dopamine-intima association appeared only in women.
The authors interpret these patterns as pointing to ethnicity-specific mechanisms. In the White group, the positive dopamine association was unexpected because renal dopamine is generally regarded as vasoprotective. The researchers propose several non-exclusive explanations: elevated urinary dopamine may represent a compensatory renal response to vascular stress, increased sodium retention or sodium-induced endothelial dysfunction; it may reflect dopamine receptor resistance, in which increased production fails to deliver adequate vascular protection; or attenuated conversion to metabolites may signal compromised intrarenal dopamine metabolism. In the Black group, where oxidative stress was higher and carotid intima-media thickness greater, elevated HVA may reflect heightened oxidative stress-driven dopamine turnover, a maladaptive compensatory metabolism rather than effective receptor-mediated signalling, plausibly linked to the vascular remodelling observed in this group.
The study’s strengths include 24-hour ambulatory blood pressure assessment and the overnight facility stay with a standardised meal. The authors also note important limitations: the absence of 24-hour urine collection for dopamine, its metabolites and sodium; the cross-sectional design, which precludes causal inference; a homogeneous occupational sample that limits generalizability to the broader South African population; and the lack of stratification by age and body mass index categories. Because the data are observational, the reported associations cannot establish whether dopamine changes drive arterial thickening or vice versa. If future larger longitudinal studies confirm these links, the authors suggest, renal dopamine could emerge as a target for early interventions aimed at maintaining vascular health, particularly in high-risk groups.
Subject of Research: Ethnicity-specific associations between urinary dopamine, its metabolites and arterial health markers in South African adults
Article Title: Exploring the Link Between Markers of Arterial Health and Urinary Dopamine in South African Adults: The SABPA Study
Article References: Mothae, M. M., Kruger, R., & Gafane-Matemane, L. F. (2026). Exploring the Link Between Markers of Arterial Health and Urinary Dopamine in South African Adults: The SABPA Study. Artery Research, 32(1), Article 25. https://doi.org/10.1007/s44200-026-00123-0
Image Credits: AI Generated
DOI: 10.1007/s44200-026-00123-0
Keywords: urinary dopamine, carotid intima-media thickness, arterial health, SABPA study, South African adults, ethnicity, oxidative stress, homovanillic acid, blood pressure, renal physiology, atherosclerosis, pulse wave velocity
News Source: Ophelia Keating. (October 30, 2026). Urinary Dopamine Tracks Artery Wall Thickness Differently in Black and White South African Adults. Scienmag.
