Racial Differences in Control of Blood Vessel Tone and Blood Flow
Information source: National Institutes of Health Clinical Center (CC)
Information obtained from ClinicalTrials.gov on June 20, 2008
Link to the current ClinicalTrials.gov record.
Condition(s) targeted: Atherosclerosis; Healthy; Hypertension
Phase: N/A
Status: Completed
Sponsored by: National Heart, Lung, and Blood Institute (NHLBI)
Summary
Black Americans tend to die more often from and have more diseases associated with heart
disease than White Americans. The exact cause of this is unknown, but it is likely a
combination of genetics, behavior, risk factors, strategies for education and prevention, and
socioeconomic factors.
Recent studies have suggested that faster biological processes in blood vessels of Black
Americans may be the cause of increased amounts of heart disease. In addition, small blood
vessels in Black Americans seem to be less responsive to substances that relax blood vessels,
which may explain increased blood pressure levels.
In this study researchers plan to study artery relaxation (dilation) in response substances
affecting the cells lining blood vessels (endothelin). Researchers will compare the results
of this study in black and white people to find out whether racial differences may contribute
to increases in heart disease and heart related deaths in blacks.
Clinical Details
Official title: Racial Differences in Flow Mediated Vasodilator Function
Study design: N/A
Detailed description:
Black Americans have a greater morbidity and mortality related to cardiovascular diseases
compared to whites. The cause for this phenomenon is probably multifactorial and includes
differences in pathogenesis, risk factor patterns, genetic background, behavioral variables,
strategies for education and prevention, and socioeconomic factors. Recent evidence suggests
that acceleration of some of the processes related to vascular biology may account for the
greater prevalence of cardiovascular disease in blacks. A diminished vasodilator response of
the microvasculature has been shown in African Americans and may therefore be responsible for
their increased prevalence of hypertension. Endothelial dysfunction is a central mechanism
in the development of atherosclerosis. It is therefore reasonable to postulate that
endothelial dysfunction of large conductance arteries may also contribute to a greater
susceptibility to atherosclerosis in blacks compared to whites, even in those individuals
without the known risk factors for coronary heart disease. In the present study, we propose
to investigate brachial artery dilation in response to endothelium-dependent and - independent
stimuli in black and white individuals to determine whether racial differences in the
vascular biology of large conductance vessels that might contribute to the greater
cardiovascular morbidity and mortality previously reported in blacks.
Eligibility
Minimum age: N/A.
Maximum age: N/A.
Gender(s): Both.
Criteria:
Black and white normal volunteers, approximately matched for age and sex, will be included
in the study.
All subjects must be capable of rendering informed consent for all procedures.
Volunteers with a history or evidence of present or past hypertension (BP greater than
140/90), diabetes mellitus, hypercholesterolemia (plasma cholesterol greater than 200
mg/dL), cardiac disease, peripheral vascular disease, coagulopathy, chronic smoking (2
pack-years or more), obesity (20% greater than ideal body weight), hyperhomocysteinemia
(plasma homocysteine greater than 17 umol/1) or any other disease predisposing them to
vasculitis will be excluded from the study.
No pregnant women.
Volunteers who are taking any medication will be excluded.
Locations and Contacts
National Heart, Lung and Blood Institute (NHLBI), Bethesda, Maryland 20892, United States
Additional Information
Related publications: Hutchinson RG, Watson RL, Davis CE, Barnes R, Brown S, Romm F, Spencer JM, Tyroler HA, Wu K. Racial differences in risk factors for atherosclerosis. The ARIC Study. Atherosclerosis Risk in Communities. Angiology. 1997 Apr;48(4):279-90. Geronimus AT, Bound J, Waidmann TA, Hillemeier MM, Burns PB. Excess mortality among blacks and whites in the United States. N Engl J Med. 1996 Nov 21;335(21):1552-8. Fang J, Madhavan S, Alderman MH. The association between birthplace and mortality from cardiovascular causes among black and white residents of New York City. N Engl J Med. 1996 Nov 21;335(21):1545-51.
Starting date: May 1998
Ending date: March 2001
Last updated: March 3, 2008
|
