Renal perfusion and function in healthy African Americans.
BACKGROUND
Despite their increased risk of nephropathy, remarkably little is known about renal perfusion and function in healthy African Americans.


METHODS
We enrolled 32 healthy African Americans and compared renal perfusion and function in 82 age-matched healthy Caucasians. Studies were performed on a diet containing 200 mmol of sodium and 100 mmol of potassium per day. In a separate study of 28 subjects, 10 African American and 18 Caucasians, the contribution of the renin-angiotensin system was assessed by measuring renal hemodynamic responses to angiotension II (Ang II) and captopril.


RESULTS
Although glomerular filtration rate (GFR) was similar, renal plasma flow (RPF) was significantly less in age-matched African Americans (568 +/- 18) than Caucasians (620 +/- 13 mL/min/1.73 m(2), P = 0.0063). After captopril, African Americans had a sevenfold greater vasodilator response and a rise in RPF (35.3 +/- 4.9 vs. 4.9 +/- 12.4 mL/min/1.73 m(2) in African Americans and Caucasians, respectively, P < 0.028). Ang II administration caused a significantly smaller vasoconstrictor response in African Americans (Ang II-induced fall in RPF, -97 +/- 18 vs. -150 +/- 9 mL/min/1.73 m(2), P = 0.05), and angiotensin-converting enzyme (ACE) inhibition enhanced the response to Ang II in African Americans significantly.


CONCLUSIONS
A reduction in RPF, blunting of the renal vascular response to Ang II, and an accentuated renal vasodilator response to captopril, which in turn corrects the blunting of responsiveness to Ang II, all suggest activation of the renin system in apparently healthy African Americans. As PRA was identical in Caucasians and African Americans, the findings suggest that it is the intrarenal-renin system that is activated in African Americans. This difference in normal control mechanisms could predispose to nephropathy.
Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02215, USA. daprice@partners.org
D A
DA
Price
N D
ND
Fisher
S Y
SY
Osei
M C
MC
Lansang
N K
NK
Hollenberg
D000328:Adult; D001741:Black or African American; D000804:Angiotensin II / Q000494:pharmacology; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology; D044383:Black People; D002216:Captopril / Q000494:pharmacology; D005919:Glomerular Filtration Rate; D006801:Humans; D007668:Kidney / Q000502:physiology*; D012016:Reference Values; D012079:Renal Circulation / Q000187:drug effects; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014664:Vasodilation / Q000187:drug effects; D044465:White People
D000806:Angiotensin-Converting Enzyme Inhibitors; D014662:Vasoconstrictor Agents; D000804:Angiotensin II; D002216:Captopril