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Updated: Apr 30, 2026
Non-invasive Assessment of Microvascular and Endothelial Function
Published on: January 29, 2013
Ethnic differences in microvascular function in apparently healthy South African men and women
P R Pienaar1, L K Micklesfield2, J M R Gill3
1UCT/MRC Research Unit for Exercise Science and Sports Medicine, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa pnrpau001@myuct.ac.za.
Insights
Ethnic differences in microvascular function were observed in young adults. Endothelium-independent function varied significantly by ethnicity, even after adjusting for skin resistance, suggesting a role in cardiovascular disease disparities.
Area of Science:
- Cardiovascular Science
- Microvascular Physiology
- Ethnic Health Disparities
Background:
- Microvascular dysfunction is an early indicator of cardiovascular disease.
- Significant ethnic disparities exist in cardiovascular disease prevalence and outcomes.
- Understanding ethnic variations in microvascular function is crucial for targeted prevention strategies.
Purpose of the Study:
- To investigate ethnic differences in microvascular endothelial function.
- To assess both endothelium-dependent and -independent microvascular responses.
- To determine the influence of skin resistance on these ethnic variations.
Main Methods:
- Studied young, healthy adults (18-33 years) from Black African, mixed ancestry, and Caucasian backgrounds.
- Assessed microvascular function using laser Doppler imagery and iontophoresis of acetylcholine (ACh) and sodium nitroprusside (SNP).
- Adjusted for skin resistance to accurately interpret microvascular reactivity.
Main Results:
- Caucasian participants exhibited lower skin resistance compared to other ethnic groups.
- Endothelium-dependent responses (ACh) showed no significant ethnic differences after adjusting for skin resistance.
- Endothelium-independent responses (SNP) remained significantly higher in Caucasians, even after skin resistance adjustment.
- Diastolic blood pressure and skin resistance were inversely associated with microvascular responses.
Conclusions:
- Ethnic differences in endothelium-independent microvascular function may contribute to cardiovascular disease disparities.
- Skin resistance is a critical factor influencing the interpretation of iontophoresis-based microvascular assessments in multiethnic populations.
Abstract:
Microvascular dysfunction precedes the clinical manifestations of cardiovascular disease. Given the ethnic disparities in cardiovascular disease, we aimed to investigate ethnic differences in microvascular endothelial function in a group of young (18-33 years old), apparently healthy individuals (n = 33, nine Black African, 12 mixed ancestry and 12 Caucasian). Microvascular endothelium-dependent and -independent function was assessed by laser Doppler imagery and iontophoresis of ACh and sodium nitroprusside (SNP), respectively, adjusting for skin resistance. Microvascular reactivity was expressed as maximum absolute perfusion, percentage change from baseline and area under the curve (AUC). Skin resistance was significantly lower in the Caucasian group in response to ACh (Caucasian, mean 0.16 ± 0.03 Ω versus Black, 0.21 ± 0.04 Ω and mixed ancestry, 0.20 ± 0.02 Ω, P < 0.01) and SNP (Caucasian, 0.08 ± 0.01 Ω versus Black, 0.11 ± 0.02 Ω and mixed ancestry, 0.12 ± 0.01 Ω, P < 0.01). Microvascular function in response to ACh was significantly higher in the Caucasian group compared with the other two groups; however, after adjusting for skin resistance these differences were no longer significant. Conversely, the microvascular SNP response remained significantly higher in the Caucasian group, even after adjusting for skin resistance (P < 0.01). Diastolic blood pressure was inversely associated with the AUC of ACh (r = -0.4) and all SNP responses (r = -0.3 to -0.6). Skin resistance was inversely associated with AUC and maximum absolute ACh response (r = -0.59 and -0.64, respectively) and all SNP responses (r = -0.37 to -0.79). Ethnic differences in endothelium-independent microvascular function may contribute to ethnic disparities in cardiovascular disease. Moreover, skin resistance plays a significant role in the interpretation of the microvascular response to outcomes of iontophoresis in a multiethnic group.
