Endothelial Hyperpolarization in Humans

Phase 2

Terminated

Conditions: Hyperlipidemia

Interventions: Drug: Tetraethylammonium (TEA)
Drug: L-NG-monomethyl Arginine (L-NMMA)
Drug: Bradykinin
Drug: Sodium nitroprusside
Drug: Acetylcholine
Drug: Saline
Drug: Fluconazole

Registration Number: NCT00166166

Lead Sponsor: Emory University

Brief Summary: 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.

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.

Recruitment & Eligibility

Status: TERMINATED

Sex: All

Target Recruitment: 174

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 & Design

Study Type: INTERVENTIONAL

Study Design: SINGLE_GROUP

Arm && Interventions

Group	Intervention	Description
Healthy Controls	Fluconazole	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
Risk Factors	Tetraethylammonium (TEA)	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
Healthy Controls	Tetraethylammonium (TEA)	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
Healthy Controls	Bradykinin	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
Healthy Controls	Acetylcholine	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
Healthy Controls	L-NG-monomethyl Arginine (L-NMMA)	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
Risk Factors	L-NG-monomethyl Arginine (L-NMMA)	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
Risk Factors	Sodium nitroprusside	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
Healthy Controls	Saline	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
Healthy Controls	Sodium nitroprusside	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
Risk Factors	Saline	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
Risk Factors	Bradykinin	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
Risk Factors	Fluconazole	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
Risk Factors	Acetylcholine	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

Primary Outcome Measures

Name	Time	Method
Percent Change in Forearm Blood Flow (FBF) After Administration of L-NG-monomethyl Arginine (L-NMMA)	Baseline, 5 minutes	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.
Percent Change in Forearm Blood Flow (FBF) After Tetraethylammonium (TEA) Administration	Baseline, 5 minutes	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.

Secondary Outcome Measures

Name	Time	Method
Percent Change in Forearm Blood Flow (FBF) After Administration of L-NG-monomethyl Arginine (L-NMMA) and Tetraethylammonium (TEA)	5 minutes, 10 minutes	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.
Percent Change in Forearm Blood Flow (FBF) After L-NG-monomethyl Arginine (L-NMMA) and Fluconazole Administration	5 minutes, 10 minutes	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.
Forearm Blood Flow (FBF) After Sodium Nitroprusside Administration	5 minutes	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.
Change in Tissue Plasminogen Activator (t-PA) Release After Tetraethylammonium (TEA) and Bradykinin Administration	30 minutes, 60 minutes	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
Percent Change in Forearm Blood Flow (FBF) After Fluconazole Administration	Baseline, 5 minutes	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.
Change in Tissue Plasminogen Activator (t-PA) Release	Baseline, 30 minutes	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
Percent Change in Forearm Blood Flow (FBF) After Fluconazole and Tetraethylammonium (TEA) Administration	5 minutes, 10 minutes	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.
Change in Tissue Plasminogen Activator (t-PA) Release After Fluconazole and Bradykinin Administration	30 minutes, 60 minutes	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
Change in Tissue Plasminogen Activator (t-PA) Release After Fluconazole, Tetraethylammonium (TEA), and Bradykinin Administration	60 minutes, 90 minutes	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