Diabetes Mellitus, Endothelial Function, Hypertension
Conditions
Keywords
Endothelial dysfunction, Blood vessel stiffness, Nitric oxide, Oxidative stress
Brief summary
We are comparing the blood pressure-lowering effects of two marketed medications, Coreg CR and Toprol XL. Although both drugs reduce blood pressure by blocking the action of noradrenaline on beta-receptors in the blood vessels, Coreg CR also blocks alpha-receptors, which may provide added blood pressure-lowering. In addition, Coreg CR may have anti-oxidant actions. Cells which line blood vessels (termed endothelial cells) make nitric oxide (NO), which relaxes the muscle cells encircling the blood vessels, causing a reduction in blood pressure. When body cells use oxygen, they normally produce free radicals, which can destroy NO,leading to high blood pressure, heart damage and worsenimg of diabetes. Antioxidants remove free radicals and prevent or repair this damage. In this study we will measure endothelial cell function, blood vessel wall stiffness, NO in exhaled breath, and blood levels of substances which reflect NO production and destruction to determine if a pure beta-blocker (Toprol XL) differs from an alpha/beta blocker (Coreg CR) in these effects. We will also examine the mechanism by which such differences might occur.
Detailed description
The following techniques will be used: Endothelial function will be measured non-invasively by flow-mediated changes in pulsatile blood volume in the finger-tips. Vascular compliance (stiffness) will be assessed by tonometry of the radial pulse wave (augmentation index) and diastolic puse wave analysis. Plasma nitrate/nitrite levels mirror NO production and will be measured spectrophotometrically by the Griess reaction. Plasma nitrotyrosine, an in vivo marker of NO-dependent damage induced by reactive nitrogen intermediates derived from NO, will be measured by ELISA. Exhaled NO may provide an real-time measure of endothelial cell NO production and can be measured by a hand-held device which contains an electrochemical detector sensitive to 5 ppb.
Interventions
DRUGcarvedilol
capsules in doses of 20, 40, and 80 mg; once daily; 12 weeks duration
DRUGmetoprolol extended release
tablets in doses 50, 100, and 200 mg; once daily; 12 weeks duration
Sponsors
State University of New York - Downstate Medical Center
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
18 Years to 80 Years
Healthy volunteers
No
Inclusion criteria
1. Type 2 diabetes mellitus, 2. Stable antidiabetic regimen for 3 months 3. Hemoglobin A1c \<8.6% 4. Stable antihypertensive medication regimen for 3 months or more, including either an angiotensin-converting enzyme inhibitor or angiotensin receptor blocker
Exclusion criteria
1. Any clinically significant abnormality on history, physical examination, or laboratory testing which could preclude safe completion of the study 2. Significant cardiac conditions 3. Lung disease 4. Cigarette smoking 5. Chronic kidney disease (Stage 3 or greater) 6. Type 1 diabetes 7. Known contraindication to alpha- or beta-blocker therapy
Design outcomes
Primary
| Measure | Time frame |
|---|---|
| Effect of Coreg CR compared to Toprol XL on endothelial function, vascular compliance, and parameters of oxidative stress from time of randomization to study drug termination | 12 weeks |
Countries
United States
Contacts
Primary ContactNathaniel Winer, M.D.
Backup ContactRozina Rana, M.D.
Outcome results
None listed