Effects of Urocortins on Forearm Arterial Blood Flow in Healthy Volunteers (Protocol 3)

Effects of Urocortins on Forearm Arterial Blood Flow in Healthy Volunteers

Impairment of the heart's pumping capacity (heart failure) remains a major clinical problem with a poor prognosis and the search for novel treatments remains an important area of research.

Urocortins are proteins that appear to increase blood flow and heart pumping activity. There has been particular interest in the role of Urocortins 2 & 3 (subtypes of Urocortins) in heart failure.

In this study, we will examine the effects and mechanisms of Urocortins 2 & 3 on forearm blood flow and release of natural blood clot dissolving factors in the forearm circulation of healthy volunteers. In particular, we look at the endothelial mechanisms of vasodilatation of Urocortin 2 and 3.

In this study, we will look at the role of the lining of the blood vessel (endothelium) in response to urocortin types 2 and 3. We hypothesise that urocortins 2 & 3 act via the endothelium to cause dilatation of the blood vessels and release of tissue-plasminogen activating factor (blood clot dissolving factor). We also hypothesise that urocortins have a role in maintaining the normal baseline level of blood flow in forearm arteries. In addition to the above, we will also look at the effect of temporarily blocking the effect of urocortins, using a specially designed blocker drug (Astressin 2B).

Utilising the well-established technique of 'forearm venous occlusion plethysmography', we will be able to focus on the local effects of urocortins on arterial blood flow in forearm vessels, without affecting this system in the body as a whole.

Study Overview

• Status: Completed
• Conditions: Heart Disease; Vascular Disease
• Intervention / Treatment: Drug: NO clamp; Drug: Saline; Drug: Fluconazole; Drug: Aspirin; Drug: Combined

• Study Type: Interventional
• Enrollment (Actual): 10
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United Kingdom
  • Mid Lothian
    • Edinburgh, Mid Lothian, United Kingdom, EH16 4SA
      • Wellcome Trust Clinical Research Facility, Royal Infirmary of Edinburgh

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 65 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: Male

Description

Inclusion Criteria:

• Healthy male volunteers between 18 - 65 years (inclusive)

Exclusion Criteria:

• Lack of informed consent- Age <18 years > 65 years
• Current involvement in a clinical trial
• Severe or significant co-morbidity including bleeding diathesis, renal or hepatic failure
• Smoker
• History of anaemia
• Recent infective/inflammatory condition
• Recent blood donation (prior 3 months)
• Positive baseline urine test for drugs of abuse (including cannabinoids, benzodiazepines, opiates, cocaine and amphetamines)
• History of allergy to Aspirin

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Double

Number of Arms

5

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Nitric Oxide Clamp; Forearm blood flow response to Urocortins 2, 3 and Substance P in the presence of Nitric Oxide clamp	Drug: NO clamp; After a 20 minute saline washout period, ascending doses of Urocortin 2, Urocortin 3 and substance P (doses as per Protocol 2) will be infused intra-arterially in the presence or the absence of the 'nitric oxide clamp' that will be commenced prior to the infusion of Urocortin 2, Urocortin 3 and substance P, and will be continued throughout the study. Baseline blood samples will be taken from both forearms at the start of the study for full blood count, cholesterol, glucose, renal function and t-PA and PAI-1 activity and antigen concentrations. Bilateral venous blood samples will be taken at baseline, immediately before the start of Ucn2/Ucn3 infusion and at the end of each dose of Ucn2/Ucn3 for subsequent calculation of net release of t-PA and PAI-1.; Other Names: Forearm vascular study - Bilateral forearm blood flow will be measured at baseline and after each dose of Ucn 2, 3 and Substance P
Placebo Comparator: Saline Placebo; Forearm blood flow response to Urocortin 2, Urocortin 3 and Substance P in the presence of saline placebo.	Drug: Saline; After a 20 minute saline washout, incremental doses of Urocortin 2, Urocortin 3 and Substance P (in doses as per Protocol 2) will be infused in the presence of saline placebo. Baseline blood samples will be taken from both forearms at the start of the study for full blood count, cholesterol, glucose, renal function and t-PA and PAI-1 activity and antigen concentrations. Bilateral venous blood samples will be taken at baseline, immediately before the start of Ucn2/Ucn3 infusion and at the end of each dose of Ucn2/Ucn3 for subsequent calculation of net release of t-PA and PAI-1.; Other Names: Forearm vascular study - Bilateral forearm blood flow will be measured at baseline and after each dose of Ucn 2, 3 and Substance P.
Experimental: Fluconazole; Forearm blood flow response to Urocortin 2, Urocortin 3 and Substance P in the presence of intra-arterial Fluconazole.	Drug: Fluconazole; After a 20 minute saline washout period, ascending doses of Urocortin 2, Urocortin 3 and substance P (doses as per Protocol 2) will be infused intra-arterially in the presence of Fluconazole (which serves to inhibit the EDHF pathway) that will be commenced prior to the infusion of Urocortin 2, Urocortin 3 and substance P, and will be continued throughout the study. Baseline blood samples will be taken from both forearms at the start of the study for full blood count, cholesterol, glucose, renal function, plasma Ucn 2 and 3 and t-PA and PAI-1 activity and antigen concentrations. Bilateral venous blood samples will be taken at after the top dose of Ucn2/Ucn3 infusion and before and after each dose of Substance P for subsequent calculation of plasma Ucn 2/ Ucn 3 and net release of t-PA and PAI-1.
Experimental: Aspirin; Forearm blood flow response to Urocortin 2, Urocortin 3 and Substance P in the presence of cyclooxygenase inhibition with Aspirin.	Drug: Aspirin; Oral Aspirin (600mg stat) will be administered 30 minutes before start of the study. After a 20 minute saline washout period, ascending doses of Urocortin 2, Urocortin 3 and substance P (doses as per Protocol 2) will be infused intra-arterially in the presence of saline. Baseline blood samples will be taken from both forearms at the start of the study for full blood count, cholesterol, glucose, renal function, plasma Ucn 2 and 3 and t-PA and PAI-1 activity and antigen concentrations. Bilateral venous blood samples will be taken at after the top dose of Ucn2/Ucn3 infusion and before and after each dose of Substance P for subsequent calculation of plasma Ucn 2/ Ucn 3 and net release of t-PA and PAI-1.
Experimental: Combined; Forearm blood flow response to Urocortin 2, Urocortin 3 and Substance P in the presence of inhibition of cycloxygenase, EDHF and NO pathways with Aspirin, Fluconazole and NO clamp.	Drug: Combined; Oral Aspirin (600mg stat) is administered 30 minutes before start of the study. After a 20 minute saline washout period, ascending doses of Urocortin 2, Urocortin 3 and substance P (doses as per Protocol 2) will be infused intra-arterially in the presence of the 'nitric oxide clamp' that will be commenced prior to the infusion of Urocortin 2, Urocortin 3 and substance P, and will be continued throughout the study. Intra-arterial Fluconazole is also commenced at the time of the Nitric oxide clamp. This serves to inhibit the cyclooxygenase, EDHF and NO pathways of endothelial vasodilatation. Blood samples are taken as per previous arms.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Forearm blood flow	The difference between forearm blood flow in response to incremental doses of Ucn2, Ucn3 and Sub P in the presence vs absence of 'the nitric oxide clamp'	3 hours

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Net t-PA release	Net release of t-PA evoked by Ucn 2, Ucn 3 and Substance P, in the presence vs absence of a 'nitric oxide clamp'.	3 hours

Collaborators and Investigators

• Sponsor: University of Edinburgh
• Collaborators: NHS Lothian

Publications and helpful links

General Publications

• Venkatasubramanian S, Griffiths ME, McLean SG, Miller MR, Luo R, Lang NN, Newby DE. Vascular effects of urocortins 2 and 3 in healthy volunteers. J Am Heart Assoc. 2013 Jan 31;2(1):e004267. doi: 10.1161/JAHA.112.004267.

Study record dates

Study Major Dates

• Study Start: July 1, 2011
• Primary Completion (Actual): January 1, 2012
• Study Completion (Actual): January 1, 2012

Study Registration Dates

• First Submitted: March 30, 2010
• First Submitted That Met QC Criteria: March 30, 2010
• First Posted (Estimate): March 31, 2010

Study Record Updates

• Last Update Posted (Estimate): May 15, 2012
• Last Update Submitted That Met QC Criteria: May 14, 2012
• Last Verified: May 1, 2012

More Information

Terms related to this study

• Keywords: Heart failure; Nitric Oxide; endothelium; Urocortin 2; Urocortin 3; Plethysmography; Forearm blood flow; Vascular; Cyclo-oxygenase pathway; EDHF
• Additional Relevant MeSH Terms: Cardiovascular Diseases; Heart Diseases; Vascular Diseases; Physiological Effects of Drugs; Neurotransmitter Agents; Molecular Mechanisms of Pharmacological Action; Anti-Infective Agents; Peripheral Nervous System Agents; Enzyme Inhibitors; Analgesics; Sensory System Agents; Anti-Inflammatory Agents, Non-Steroidal; Analgesics, Non-Narcotic; Anti-Inflammatory Agents; Antirheumatic Agents; Fibrinolytic Agents; Fibrin Modulating Agents; Platelet Aggregation Inhibitors; Cyclooxygenase Inhibitors; Antipyretics; Hormones, Hormone Substitutes, and Hormone Antagonists; Cytochrome P-450 Enzyme Inhibitors; Hormone Antagonists; Antifungal Agents; Steroid Synthesis Inhibitors; 14-alpha Demethylase Inhibitors; Cytochrome P-450 CYP2C9 Inhibitors; Cytochrome P-450 CYP2C19 Inhibitors; Aspirin; Fluconazole; Substance P; Neurokinin A
• Other Study ID Numbers: SV.Protocol 3