Pilot Study On The Role Of Nitric Oxide In Alpha 1-Adrenergic Vasoreactivity

This study has been completed.
National Institutes of Health (NIH)
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Information provided by:
University of Michigan
ClinicalTrials.gov Identifier:
First received: October 13, 2005
Last updated: November 2, 2006
Last verified: November 2006
This is a research project to test two study techniques among healthy adults. The procedures look at how blood flow is controlled by substances in blood vessels.

Condition Intervention
Blood Pressure
Procedure: Regional phenylephrine arterial infusion, Nitric Oxide Clamp

Study Type: Interventional
Study Design: Allocation: Non-Randomized
Endpoint Classification: Pharmacodynamics Study
Intervention Model: Single Group Assignment
Masking: Open Label
Primary Purpose: Educational/Counseling/Training
Official Title: Pilot Study On The Role Of Nitric Oxide In Alpha 1-Adrenergic Vasoreactivity

Resource links provided by NLM:

Further study details as provided by University of Michigan:

Primary Outcome Measures:
  • Determine whether alpha 1-adrenoceptor vasoreactivity is reproducible
  • Determine alpha 1-adrenoceptor vasoreactivity with the NO clamp technique

Estimated Enrollment: 20
Study Start Date: July 2005
Estimated Study Completion Date: June 2006
Detailed Description:

Most patients with chronic kidney disease (CKD) have high blood pressure and are at high risk for cardiovascular disease. High blood pressure can be partly caused by narrowing of blood vessels from high activity of the alpha1-adrenoceptor system in blood vessels. On the other hand, nitric oxide (NO), produced by the body, opposes the alpha 1-adrenoceptor system. NO widens blood vessels and prevents high blood pressure. We hypothesize that low availability of NO may be responsible for high activity of alpha 1-adrenoceptor system in patients with CKD. This protocol is a pilot study in healthy subjects to guide us in performing future studies in patients with CKD.

The specific aims of the pilot study, in healthy people, are to 1) determine whether alpha 1-adrenoceptor vasoreactivity is reproducible and 2) determine alpha 1-adrenoceptor vasoreactivity with the NO clamp technique. To carry out these specific aims, we will consent and enroll healthy people with normal blood pressure. After a screening visit to confirm eligibility, subjects will be admitted to the General Clinical Research Center overnight for a study the following day.

We will constrict the forearm blood vessels by giving different amounts of phenylephrine into the artery through a catheter. We will measure the subjects blood flow with venus plethysmography ( a measuring tool like a blood pressure cuff) while giving the phenylephrine. We will repeat the tests to see if we get the same results.

Then, a research medication, L-NMMA, which blocks NO in the blood vessel, will be dripped into the same artery followed by another medication nitroprusside, which gives back NO, to restore normal forearm blood flow. This procedure is called the NO clamp technique and is used to measure the effects of NO. The phenylephrine concentrations and plethysmography will be repeated again to compare vessel narrowing before and during the NO clamp. This research will teach us how to perform future studies on the relationship between NO and the alpha 1-adrenoceptor system in patients with kidney disease.


Ages Eligible for Study:   18 Years to 55 Years   (Adult)
Genders Eligible for Study:   Both
Accepts Healthy Volunteers:   Yes

Inclusion Criteria:

Healthy men and women:

  • Age 18 to 55 years
  • Who have Blood Pressure less than or equal to 120/80.

Exclusion Criteria:

Individuals with:

  • Diabetes, lung disease
  • Stomach disease, liver disease
  • Blood vessel disease
  • Kidney disease
  • High blood pressure
  • Heart disease
  • Hereditary blood disorders
  • Hematocrit (amount of red blood cells) less than 30%,
  • Who smoke
  • Women who are pregnant or lactating
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its ClinicalTrials.gov identifier: NCT00240058

United States, Michigan
University of Michigan Hospital
Ann Arbor, Michigan, United States, 48109
Sponsors and Collaborators
University of Michigan
National Institutes of Health (NIH)
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Principal Investigator: Crystal A Gadegbeku, MD Assistant Professor of Medicine, University of Michigan Health System, Department of Internal Medicine, Division of Nephrology
  More Information

ClinicalTrials.gov Identifier: NCT00240058     History of Changes
Other Study ID Numbers: DRDA05-0222  NIH # 1R33 DK 071222-01 
Study First Received: October 13, 2005
Last Updated: November 2, 2006
Health Authority: United States: Food and Drug Administration

Keywords provided by University of Michigan:
Blood Pressure
Nitric Oxide

Additional relevant MeSH terms:
Nitric Oxide
Adrenergic Agents
Bronchodilator Agents
Autonomic Agents
Peripheral Nervous System Agents
Physiological Effects of Drugs
Anti-Asthmatic Agents
Respiratory System Agents
Free Radical Scavengers
Molecular Mechanisms of Pharmacological Action
Neurotransmitter Agents
Endothelium-Dependent Relaxing Factors
Vasodilator Agents
Protective Agents
Cardiotonic Agents
Vasoconstrictor Agents
Nasal Decongestants
Adrenergic alpha-1 Receptor Agonists
Adrenergic alpha-Agonists
Adrenergic Agonists

ClinicalTrials.gov processed this record on August 25, 2016