Model System for Transient Forearm Blood Vessel Dysfunction
Status:
Completed
Trial end date:
2009-02-11
Target enrollment:
Participant gender:
Summary
This study will develop a model system that can be used to test medications for improving the
ability of blood vessels to resist damage from diseases such as heart attack and stroke. The
endothelium (inner layer of blood vessels) has built-in defense mechanisms to prevent
blockage of blood flow, including the ability to stretch the vessel when it senses that blood
flow is threatened. People with heart attack risk factors, such as high cholesterol, smoking
and diabetes lose this ability. This study will develop a model that can measure the response
to a lack of blood flow in the arm and be used to test new medicines to improve blood vessel
health.
Healthy males between 18 and 45 years of age who have no history of high blood pressure, high
cholesterol, or diabetes and who have not smoked for at least 3 months before entering the
study may be eligible to enroll.
Participants lie in an adjustable reclining bed. Small catheters (tubes) are placed in the
artery and vein of the forearm of the non-dominant arm at the inside of the elbow. Blood
samples are collected from the tubes. Then, pressure cuffs are placed on both wrists and
upper arms. A strain gauge (rubber band-type device) is placed around the forearms. The
pressure cuffs are inflated and blood flows into the forearm, stretching the strain gauge at
a rate proportional to the blood flow. Then, small doses of acetylcholine (a medicine that
causes blood vessels to expand) are injected into the artery tube. After 20 minutes, blood
flow to the non-dominant arm is blocked by inflating the pressure cuff. The subject squeezes
a rubber ball about every 2 seconds for 90 seconds. The cuff is deflated after 15 minutes and
blood samples are withdrawn from the tube in the vein. After 15 minutes, the procedure is
repeated one more time.