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Renal perfusion and function in healthy African Americans
D A Price1, N D Fisher, S Y Osei
1Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02215, USA. daprice@partners.org
Kidney International
|March 7, 2001
Summary
Healthy African Americans exhibit reduced renal plasma flow and altered renin-angiotensin system responses, suggesting intrarenal activation that may increase nephropathy risk. These findings highlight key differences in renal function compared to Caucasians.
Area of Science:
- Nephrology
- Renal Physiology
- Cardiovascular Research
Background:
- African Americans have an elevated risk of nephropathy.
- Limited understanding exists regarding renal perfusion and function in healthy African Americans.
Purpose of the Study:
- To compare renal perfusion and function between healthy African Americans and Caucasians.
- To investigate the role of the renin-angiotensin system in renal hemodynamics in these populations.
Main Methods:
- Compared renal plasma flow (RPF) and glomerular filtration rate (GFR) in 32 healthy African Americans and 82 age-matched healthy Caucasians.
- Assessed renal hemodynamic responses to angiotensin II (Ang II) and captopril in a subset of 28 subjects (10 African American, 18 Caucasian).
- Standardized dietary sodium and potassium intake for all participants.
Main Results:
- African Americans showed significantly lower RPF (568 mL/min/1.73 m²) compared to Caucasians (620 mL/min/1.73 m²), despite similar GFR.
- African Americans exhibited a greater vasodilator response to captopril and a blunted vasoconstrictor response to Ang II.
- Angiotensin-converting enzyme (ACE) inhibition with captopril enhanced Ang II responsiveness in African Americans.
Conclusions:
- Reduced RPF and altered renal vascular responses to Ang II and captopril suggest activated intrarenal renin system in healthy African Americans.
- Identical plasma renin activity (PRA) between groups indicates localized intrarenal activation, not systemic.
- These differences in renal control mechanisms may contribute to the predisposition to nephropathy in African Americans.