Pilot Study On The Role Of Nitric Oxide In Alpha 1-Adrenergic Vasoreactivity
Drug: Regional phenylephrine arterial infusion, Nitric Oxide Clamp
|Study Design:||Allocation: Non-Randomized
Endpoint Classification: Pharmacodynamics Study
Intervention Model: Single Group Assignment
Masking: Open Label
|Official Title:||Pilot Study On The Role Of Nitric Oxide In Alpha 1-Adrenergic Vasoreactivity|
- Determine whether alpha 1-adrenoceptor vasoreactivity is reproducible [ Designated as safety issue: No ]
- Determine alpha 1-adrenoceptor vasoreactivity with the NO clamp technique [ Designated as safety issue: No ]
|Study Start Date:||July 2005|
|Study Completion Date:||June 2006|
|Primary Completion Date:||June 2006 (Final data collection date for primary outcome measure)|
phenylephrine infusion with and without nitric oxide clamp
Participants received phenylephrine infusion with saline followed by phenylephrine infusion with nitric oxide clamp
|Drug: Regional phenylephrine arterial infusion, Nitric Oxide Clamp|
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.
Please refer to this study by its ClinicalTrials.gov identifier: NCT00240058
|United States, Michigan|
|University of Michigan Hospital|
|Ann Arbor, Michigan, United States, 48109|
|Principal Investigator:||Crystal A Gadegbeku, MD||Assistant Professor of Medicine, University of Michigan Health System, Department of Internal Medicine, Division of Nephrology|