Reversing Glucose and Lipid-mediated Vascular Dysfunction

Study Overview
=================
Brief Summary
-----------------
The purpose of our study is to understand the extent to which the blood vessels are affected by glucose and fat (lipids) in lean healthy adults and if these changes in the blood vessels contribute to the development of high blood pressure.

Detailed Description
-----------------
Hypertension, obesity, and insulin resistance are associated with elevated muscle sympathetic nerve activity (MSNA), which is important for blood pressure regulation. The measurement of MSNA is safely performed in humans using the microneurographic technique that involves recording sympathetic nerve activity projecting to skeletal muscle using a small microelectrode at the peroneal nerve near the knee. The health of your blood vessels will be tested in this study, in addition to the activity of the nerves that control the blood vessels. The function of the nerves and blood vessels can be diminished by high blood glucose and lipids, and we will test the ability of a well-known antioxidant, ascorbic acid (vitamin C), to restore the function of the nerves and blood vessels.

Official Title
-----------------
Reversing Glucose and Lipid-mediated Vascular Dysfunction (REGAL)

Conditions
-----------------
Blood Pressure, Hypertension

Intervention / Treatment
-----------------
* Drug: Dextrose 20 % in 500 ML Injection
* Drug: Intralipid
* Drug: Saline
* Drug: Ascorbic acid


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Lean: BMI < 25 kg/m Normal insulin sensitivity: (calculation based on fasting glucose and insulin concentrations in blood) Middle-aged: 18-79 years Blood pressure: < 140 (systolic) and < 90 mmHg (diastolic Weight stable (+/- 5 lbs) for the previous 3 months Participants must be willing and able to discontinue taking any vitamin C or E supplements or omega-3 fatty acids beginning 2 weeks prior. Able and willing to provide written informed consent Exclusion Criteria: Diabetes mellitus Type I or Type II: fasting glucose < 126 mg/dL and/or HbA1c < 6.5% Current smoker or History of smoking in the past 3 months. Hyperlipidemia: Fasting triglycerides < 250 mg/dL Hypertension: >130/80 mmHg History of heart disease (e.g., myocardial infarction, stent, heart attack, stroke, heart failure, valvular heart disease, cardiomyopathy) History of vascular disease (e.g., bypass, stroke)

Ages Eligible for Study
-----------------
Minimum Age: 18 Years
Maximum Age: 79 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
Accepts Healthy Volunteers

Study Plan
=================
How is the study designed?
-----------------

Design Details

Primary Purpose: Other
Allocation: Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: Comparisons of outcome variables will be made using a mixed model ANOVA.
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Glucose Infusion<br>Hyperglycemia (glucose infusion) will receive an I.V. Glucose infusion with a co-infusion of ascorbic acid or placebo at your visit 2 and the alternative treatment of ascorbic acid or placebo will be given on the subsequent study visit 3. | Drug: Dextrose 20 % in 500 ML Injection<br>* Dextrose (20% intravenous solution) will be obtained from the Investigational Pharmacy located in the KU Clinical Research Center where studies take place. After fasting for at least 8 hours, dextrose will be administered via antecubital vein at a standard rate of 4 mg/kg/min for 2 hours.<br>* Other names: Glucose;Drug: Saline<br>* Saline will be obtained from the Investigational Pharmacy located in the KU Clinical Research Center where studies take place. Will be administered via antecubital vein at 75 to 150 mL/hour for 2 hours.<br>* Other names: Placebo;Drug: Ascorbic acid<br>* (ASCOR) will be obtained from the KU Investigational Pharmacy located in the KU Clinical Research Center where studies will take place. A priming bolus of 0.06 g ascorbic acid/kg fat free mass (FFM) dissolved in 100 mL of saline will be infused intravenously at 5 mL/min for 20 minutes, followed immediately by a drip-infusion of 0.02 g/kg FFM dissolved in 30 mL of saline administered over 2 hours at 0.5 mL/min. The KU Investigational Pharmacy will randomize ascorbic acid or placebo (saline) for each participant.<br>|
| Experimental: Lipid Infusion<br>Hyperlipidemia (lipid infusion) will receive an I.V. Lipid infusion with a co-infusion of ascorbic acid or placebo at your visit 2 and the alternative treatment of ascorbic acid or placebo will be given on the subsequent study visit 3. | Drug: Intralipid<br>* Intralipid ® 20% will be obtained from the Investigational Pharmacy located in the KU Clinical Research Center where studies take place. After fasting for at least 8 hours, Intralipid ® 20% will be administered via antecubital vein at 0.75 mL/min for 2 hours Increases in circulating markers of oxidative stress peak within 2 hours of Intralipid ® 20% infusion in healthy adults (42). An initial heparin bolus of 1000 UL followed by 200 U/hr infusion will be included to activate endothelial lipoprotein lipase and accelerate hydrolysis of fatty acids.<br>* Other names: Lipid;Drug: Saline<br>* Saline will be obtained from the Investigational Pharmacy located in the KU Clinical Research Center where studies take place. Will be administered via antecubital vein at 75 to 150 mL/hour for 2 hours.<br>* Other names: Placebo;Drug: Ascorbic acid<br>* (ASCOR) will be obtained from the KU Investigational Pharmacy located in the KU Clinical Research Center where studies will take place. A priming bolus of 0.06 g ascorbic acid/kg fat free mass (FFM) dissolved in 100 mL of saline will be infused intravenously at 5 mL/min for 20 minutes, followed immediately by a drip-infusion of 0.02 g/kg FFM dissolved in 30 mL of saline administered over 2 hours at 0.5 mL/min. The KU Investigational Pharmacy will randomize ascorbic acid or placebo (saline) for each participant.<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Efficacy of Infusion of Ascorbic Acid | The difference in sympathetic-vascular transduction (mmHg) between ascorbic acid and placebo infusion will be taken as a measure of the modulation of SVT by oxidative stress. | Baseline | 
| Efficacy of Infusion of Ascorbic Acid | The difference in sympathetic-vascular transduction (mmHg) between ascorbic acid and placebo infusion will be taken as a measure of the modulation of SVT by oxidative stress. | 30 minutes | 
| Efficacy of Infusion of Ascorbic Acid | The difference in sympathetic-vascular transduction (mmHg) between ascorbic acid and placebo infusion will be taken as a measure of the modulation of SVT by oxidative stress. | 60 minutes | 
| Efficacy of Infusion of Ascorbic Acid | The difference in sympathetic-vascular transduction (mmHg) between ascorbic acid and placebo infusion will be taken as a measure of the modulation of SVT by oxidative stress. | 90 minutes | 
| Efficacy of Infusion of Ascorbic Acid | The difference in sympathetic-vascular transduction (mmHg) between ascorbic acid and placebo infusion will be taken as a measure of the modulation of SVT by oxidative stress. | 120 minutes |