Endothelial Hyperpolarization in Humans

Physiology and Pathologic Role of Endothelium-Derived Hyperpolarizing Factor in Humans

The purpose of this study is to elucidate the role Endothelium-Derived Hyperpolarizing Factor (EDHF) plays in dilating blood vessels and whether it differs between healthy people and those with high cholesterol. A second purpose of the study is to determine the identity of EDHF.

Study Overview

• Status: Terminated
• Conditions: Hyperlipidemia
• Intervention / Treatment: Drug: Tetraethylammonium (TEA); Drug: L-NG-monomethyl Arginine (L-NMMA); Drug: Bradykinin; Drug: Sodium nitroprusside; Drug: Acetylcholine; Drug: Saline; Drug: Fluconazole

Detailed Description

The vascular endothelium synthesizes at least four potent vasodilator substances: nitric oxide (NO), prostacyclin, carbon monoxide and endothelium-derived hyperpolarizing factor (EDHF) that contribute to vasodilator tone, and to inhibition of platelet activation and inflammation. EDHF release is stimulated by receptor-dependent agonists such as acetylcholine and bradykinin (BK), and leads to hyperpolarization of the underlying smooth muscle cells presumably by opening Ca2+-activated K+ channels. Indirect pharmacological evidence suggests that EDHF is a cytochrome P450-derived arachidonic acid metabolite, presumably an epoxide. Although the pivotal role of NO to conduit vessel dilation in response to acute increases in shear stress is well known, its' contribution to dilation with sustained increases in flow are minimal, and may be due to EDHF release.

• Study Type: Interventional
• Enrollment (Actual): 174
• Phase: Phase 2

Contacts and Locations

Study Locations

• United States
  • Georgia
    • Atlanta, Georgia, United States, 30322
      • Emory University School of Medicine

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 21 years to 65 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• Hyperlipidemic (LDL > 140)
• Healthy Volunteer

Exclusion Criteria:

• Pregnancy
• Diabetes mellitus
• Cardiovascular Disease
• Hypertension
• Use of any regular medications
• Renal insufficiency
• Smoking (current or within the past 5 years)
• Bleeding disorder

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Diagnostic
• Allocation: Non-Randomized
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Healthy Controls; Healthy subjects had venous occlusion plethysmography after intra-arterial infusions of saline, L-NG-monomethyl Arginine (L-NMMA), Tetraethylammonium (TEA), fluconazole, bradykinin, sodium nitroprusside and acetylcholine	Drug: Tetraethylammonium (TEA); 5 minute intra-arterial infusion of Tetraethylammonium at 1 mg/min; Drug: L-NG-monomethyl Arginine (L-NMMA); 5 minute intra-arterial infusion of L-NMMA 8 μmol/min; Other Names: Methylarginine; Drug: Bradykinin; Intra-arterial infusion of bradykinin at 100, 200, and 400 ng/min. Each dose will be given for 5 minutes.; Drug: Sodium nitroprusside; Intra-arterial infusion of sodium nitroprusside at 1.6 and 3.2 mg/min. Each dose will be given for 5 minutes.; Other Names: Nitropress; Drug: Acetylcholine; Intra-arterial infusion of acetylcholine at 7.5, 15 and 30 μg/min. Each dose will be given for 5 minutes.; Drug: Saline; 5 minute intra-arterial infusion of 0.9% saline at 2.5ml/min; Drug: Fluconazole; 5 minute intra-arterial infusion of fluconazole at 0.4 mg/L/min; Other Names: Diflucan
Experimental: Risk Factors; Non-hypertensive subjects with cardiovascular risk factors had venous occlusion plethysmography after intra-arterial infusions of saline, L-NG-monomethyl Arginine (L-NMMA), Tetraethylammonium (TEA), fluconazole, bradykinin, sodium nitroprusside and acetylcholine	Drug: Tetraethylammonium (TEA); 5 minute intra-arterial infusion of Tetraethylammonium at 1 mg/min; Drug: L-NG-monomethyl Arginine (L-NMMA); 5 minute intra-arterial infusion of L-NMMA 8 μmol/min; Other Names: Methylarginine; Drug: Bradykinin; Intra-arterial infusion of bradykinin at 100, 200, and 400 ng/min. Each dose will be given for 5 minutes.; Drug: Sodium nitroprusside; Intra-arterial infusion of sodium nitroprusside at 1.6 and 3.2 mg/min. Each dose will be given for 5 minutes.; Other Names: Nitropress; Drug: Acetylcholine; Intra-arterial infusion of acetylcholine at 7.5, 15 and 30 μg/min. Each dose will be given for 5 minutes.; Drug: Saline; 5 minute intra-arterial infusion of 0.9% saline at 2.5ml/min; Drug: Fluconazole; 5 minute intra-arterial infusion of fluconazole at 0.4 mg/L/min; Other Names: Diflucan

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Percent Change in Forearm Blood Flow (FBF) After Tetraethylammonium (TEA) Administration	Simultaneous forearm blood flow (FBF) measurements were obtained in both arms using a dual-channel venous occlusion strain gauge plethysmograph at rest and after administration of tetraethylammonium (TEA). Flow measurements were recorded for approximately 7 seconds, every 15 seconds up to eight times and a mean FBF value was computed. Percent change is the difference from baseline FBF and after TEA administration.	Baseline, 5 minutes
Percent Change in Forearm Blood Flow (FBF) After Administration of L-NG-monomethyl Arginine (L-NMMA)	Simultaneous forearm blood flow (FBF) measurements were obtained in both arms using a dual-channel venous occlusion strain gauge plethysmograph after administration of L-NG-monomethyl Arginine (L-NMMA). Flow measurements were recorded for approximately 7 seconds, every 15 seconds up to eight times and a mean FBF value was computed. Percent change is the difference in FBF from baseline and after L-NMMA administration.	Baseline, 5 minutes

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Percent Change in Forearm Blood Flow (FBF) After Administration of L-NG-monomethyl Arginine (L-NMMA) and Tetraethylammonium (TEA)	Simultaneous forearm blood flow (FBF) measurements were obtained in both arms using a dual-channel venous occlusion strain gauge plethysmograph after administration of L-NG-monomethyl Arginine (L-NMMA) and Tetraethylammonium (TEA). Flow measurements were recorded for approximately 7 seconds, every 15 seconds up to eight times and a mean FBF value was computed. Percent change is the difference in FBF from after L-NMMA administration and after TEA administration.	5 minutes, 10 minutes
Percent Change in Forearm Blood Flow (FBF) After Fluconazole Administration	Simultaneous forearm blood flow (FBF) measurements were obtained in both arms using a dual-channel venous occlusion strain gauge plethysmograph at rest and after administration of fluconazole. Flow measurements were recorded for approximately 7 seconds, every 15 seconds up to eight times and a mean FBF value was computed. Percent change is the difference from baseline FBF and after fluconazole administration.	Baseline, 5 minutes
Percent Change in Forearm Blood Flow (FBF) After L-NG-monomethyl Arginine (L-NMMA) and Fluconazole Administration	Simultaneous forearm blood flow (FBF) measurements were obtained in both arms using a dual-channel venous occlusion strain gauge plethysmograph after L-NMMA administration and administration of fluconazole. Flow measurements were recorded for approximately 7 seconds, every 15 seconds up to eight times and a mean FBF value was computed. Percent change is the difference in FBF after L-NMMA administration and then fluconazole administration.	5 minutes, 10 minutes
Percent Change in Forearm Blood Flow (FBF) After Fluconazole and Tetraethylammonium (TEA) Administration	Simultaneous forearm blood flow (FBF) measurements were obtained in both arms using a dual-channel venous occlusion strain gauge plethysmograph after administration of fluconazole and Tetraethylammonium (TEA) administration. Flow measurements were recorded for approximately 7 seconds, every 15 seconds up to eight times and a mean FBF value was computed. Percent change is the difference from FBF after fluconazole administration and after Tetraethylammonium (TEA) administration.	5 minutes, 10 minutes
Forearm Blood Flow (FBF) After Sodium Nitroprusside Administration	Simultaneous forearm blood flow (FBF) measurements were obtained in both arms using a dual-channel venous occlusion strain gauge plethysmograph after administration of sodium nitroprusside. Flow measurements were recorded for approximately 7 seconds, every 15 seconds up to eight times and a mean FBF value was computed.	5 minutes
Change in Tissue Plasminogen Activator (t-PA) Release	Individual net t-PA release at each time point were calculated by the following formula: net release = (Cv-CA) x {FBF x [101-hematocrit/100]}, where Cv and CA represent the concentration of t-PA in the brachial vein and artery, respectively. Change is the difference of t-PA at baseline and t-PA after bradykinin 400 ng/min	Baseline, 30 minutes
Change in Tissue Plasminogen Activator (t-PA) Release After Tetraethylammonium (TEA) and Bradykinin Administration	Individual net t-PA release at each time point were calculated by the following formula: net release = (Cv-CA) x {FBF x [101-hematocrit/100]}, where Cv and CA represent the concentration of t-PA in the brachial vein and artery, respectively. Change is the difference of t-PA after Tetraethylammonium (TEA) and t-PA after bradykinin 400 ng/min	30 minutes, 60 minutes
Change in Tissue Plasminogen Activator (t-PA) Release After Fluconazole and Bradykinin Administration	Individual net t-PA release at each time point were calculated by the following formula: net release = (Cv-CA) x {FBF x [101-hematocrit/100]}, where Cv and CA represent the concentration of t-PA in the brachial vein and artery, respectively. Change is the difference of t-PA after fluconazole and t-PA after bradykinin 400 ng/min	30 minutes, 60 minutes
Change in Tissue Plasminogen Activator (t-PA) Release After Fluconazole, Tetraethylammonium (TEA), and Bradykinin Administration	Individual net t-PA release at each time point were calculated by the following formula: net release = (Cv-CA) x {FBF x [101-hematocrit/100]}, where Cv and CA represent the concentration of t-PA in the brachial vein and artery, respectively. Change is the difference of t-PA after fluconazole and tetraethylammonium (TEA) and t-PA after bradykinin 400 ng/min	60 minutes, 90 minutes

Collaborators and Investigators

• Sponsor: Emory University
• Collaborators: National Heart, Lung, and Blood Institute (NHLBI)
• Investigators: Principal Investigator: Arshed A Quyyumi, MD, Emory University School of Medicine, Division of Cardiology

Publications and helpful links

General Publications

• Ozkor MA, Murrow JR, Rahman AM, Kavtaradze N, Lin J, Manatunga A, Quyyumi AA. Endothelium-derived hyperpolarizing factor determines resting and stimulated forearm vasodilator tone in health and in disease. Circulation. 2011 May 24;123(20):2244-53. doi: 10.1161/CIRCULATIONAHA.110.990317. Epub 2011 May 9.
• Ozkor MA, Hayek SS, Rahman AM, Murrow JR, Kavtaradze N, Lin J, Manatunga A, Quyyumi AA. Contribution of endothelium-derived hyperpolarizing factor to exercise-induced vasodilation in health and hypercholesterolemia. Vasc Med. 2015 Feb;20(1):14-22. doi: 10.1177/1358863X14565374. Epub 2015 Feb 3.
• Rahman AM, Murrow JR, Ozkor MA, Kavtaradze N, Lin J, De Staercke C, Hooper WC, Manatunga A, Hayek S, Quyyumi AA. Endothelium-derived hyperpolarizing factor mediates bradykinin-stimulated tissue plasminogen activator release in humans. J Vasc Res. 2014;51(3):200-8. doi: 10.1159/000362666. Epub 2014 Jun 4.
• Ozkor MA, Rahman AM, Murrow JR, Kavtaradze N, Lin J, Manatunga A, Hayek S, Quyyumi AA. Differences in vascular nitric oxide and endothelium-derived hyperpolarizing factor bioavailability in blacks and whites. Arterioscler Thromb Vasc Biol. 2014 Jun;34(6):1320-7. doi: 10.1161/ATVBAHA.113.303136. Epub 2014 Mar 27.

Study record dates

Study Major Dates

• Study Start: July 1, 2002
• Primary Completion (Actual): January 1, 2013
• Study Completion (Actual): January 1, 2013

Study Registration Dates

• First Submitted: September 13, 2005
• First Submitted That Met QC Criteria: September 13, 2005
• First Posted (Estimate): September 14, 2005

Study Record Updates

• Last Update Posted (Actual): August 15, 2018
• Last Update Submitted That Met QC Criteria: July 17, 2018
• Last Verified: July 1, 2018

More Information

Terms related to this study

• Keywords: EDHF; FMD; hyperlipidaemia
• Additional Relevant MeSH Terms: Metabolic Diseases; Lipid Metabolism Disorders; Dyslipidemias; Hyperlipidemias; Hyperlipoproteinemias; Physiological Effects of Drugs; Neurotransmitter Agents; Molecular Mechanisms of Pharmacological Action; Antihypertensive Agents; Vasodilator Agents; Anti-Infective Agents; Cholinergic Agents; Enzyme Inhibitors; Hormones, Hormone Substitutes, and Hormone Antagonists; Protease Inhibitors; Membrane Transport Modulators; Cytochrome P-450 Enzyme Inhibitors; Cholinergic Agonists; Hormone Antagonists; Antifungal Agents; Steroid Synthesis Inhibitors; 14-alpha Demethylase Inhibitors; Cytochrome P-450 CYP2C9 Inhibitors; Nitric Oxide Donors; Cytochrome P-450 CYP2C19 Inhibitors; Cysteine Proteinase Inhibitors; Potassium Channel Blockers; Fluconazole; Nitroprusside; Acetylcholine; omega-N-Methylarginine; Bradykinin; Kininogens; Tetraethylammonium
• Other Study ID Numbers: IRB00021886; 1R01HL079115-01 (U.S. NIH Grant/Contract); 0605-2002 (Other Identifier: Other)