Model System for Transient Forearm Blood Vessel Dysfunction

• Status: Completed
• Trial end date: 2009-02-11
• Target enrollment: 0
• Participant gender: Male

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 The cuff is deflated after 15 minutes and blood samples are withdrawn from the tube in the vein.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.

• Phase: N/A
• Accepts Healthy Volunteers?: Accepts Healthy Volunteers

Details

• Lead Sponsor: National Heart, Lung, and Blood Institute (NHLBI)
• Treatments: Acetylcholine

Criteria

• ELIGIBILITY:

Up to 20 healthy volunteers will be screened in order to obtain 10 completed studies. All volunteer subjects will undergo screening with complete history, cardiovascular physical examination, electrocardiogram, blood collection for clinical chemistry routine analyses and complete blood count, cholesterol, fasting blood glucose, PT and PTT.

INCLUSION CRITERIA:

Subjects must be 18-45 years of age.

Subjects must be male.

Subject must be in good health.

Subject must complete a screening history and physical exam.

Subjects must provide informed, written consent for participation in this study.

EXCLUSION CRITERIA:

Subjects with a history of cardiac, pulmonary, peripheral vascular disease, coagulopathy, or any other disease predisposing to vasculitis or Raynaud's phenomenon.

Subjects with diabetes or mitochondrial disease.

Subjects with a history or evidence of present or past hypertension (blood pressure greater than 140/90 mmHg), hypercholesterolemia (LDL cholesterol greater than 160 mg/dL).

Subjects with abnormal EKG other than sinus bradycardia.

Subjects who have a history of smoking within three months.

Subjects with anemia (defined as hemoglobin less than 9 g/dL).

BMI greater than 30

No volunteer subject will be allowed to take any prescription medication. Vitamin supplements, herbal preparations, nutraceuticals or other alternative therapies must be stopped for two weeks prior to study and aspirin, tylenol and NSAIDs must also be discontinued two weeks prior to study.

Subjects with a blood pressure of less than 90/60 mmHg or mean arterial pressure (MAP) less than 70 mmHg on the study day will be excluded from the protocol.

Positive for HIV or Hepatitis B, C.