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Effects of Urocortins on Forearm Arterial Blood Flow in Healthy Volunteers (Protocol 3)
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Purpose
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.
| Condition | Intervention |
|---|---|
| Vascular Disease Heart Disease | Drug: NO clamp Drug: Saline Drug: Fluconazole Drug: Aspirin Drug: Combined |
| Study Type: | Interventional |
| Study Design: | Allocation: Randomized Intervention Model: Crossover Assignment Masking: Double Blind (Participant, Investigator) Primary Purpose: Basic Science |
| Official Title: | Effects of Urocortins on Forearm Arterial Blood Flow in Healthy Volunteers |
- Forearm blood flow [ Time Frame: 3 hours ]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'
- Net t-PA release [ Time Frame: 3 hours ]Net release of t-PA evoked by Ucn 2, Ucn 3 and Substance P, in the presence vs absence of a 'nitric oxide clamp'.
| Enrollment: | 10 |
| Study Start Date: | July 2011 |
| Study Completion Date: | January 2012 |
| Primary Completion Date: | January 2012 (Final data collection date for primary outcome measure) |
| Arms | Assigned Interventions |
|---|---|
|
Experimental: Nitric Oxide Clamp
Forearm blood flow response to Urocortins 2, 3 and Substance P in the presence of Nitric Oxide clamp
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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 Name: Forearm vascular study - Bilateral forearm blood flow will be measured at baseline and after each dose of Ucn 2, 3 and Substance P
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Placebo Comparator: Saline Placebo
Forearm blood flow response to Urocortin 2, Urocortin 3 and Substance P in the presence of saline placebo.
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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 Name: Forearm vascular study - Bilateral forearm blood flow will be measured at baseline and after each dose of Ucn 2, 3 and Substance P.
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Experimental: Fluconazole
Forearm blood flow response to Urocortin 2, Urocortin 3 and Substance P in the presence of intra-arterial Fluconazole.
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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. |
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Experimental: Aspirin
Forearm blood flow response to Urocortin 2, Urocortin 3 and Substance P in the presence of cyclooxygenase inhibition with Aspirin.
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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. |
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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. |
Eligibility| Ages Eligible for Study: | 18 Years to 65 Years (Adult) |
| Sexes Eligible for Study: | Male |
| Accepts Healthy Volunteers: | Yes |
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
Contacts and LocationsPlease refer to this study by its ClinicalTrials.gov identifier: NCT01096706
| United Kingdom | |
| Wellcome Trust Clinical Research Facility, Royal Infirmary of Edinburgh | |
| Edinburgh, Mid Lothian, United Kingdom, EH16 4SA | |
| Principal Investigator: | David E Newby, PhD FRCP | University of Edinburgh |
More Information
Publications automatically indexed to this study by ClinicalTrials.gov Identifier (NCT Number):
| Responsible Party: | University of Edinburgh |
| ClinicalTrials.gov Identifier: | NCT01096706 History of Changes |
| Other Study ID Numbers: |
SV.Protocol 3 |
| Study First Received: | March 30, 2010 |
| Last Updated: | May 14, 2012 |
Keywords provided by University of Edinburgh:
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Urocortin 2 Urocortin 3 Nitric Oxide Plethysmography Forearm blood flow |
Vascular Heart failure endothelium Cyclo-oxygenase pathway EDHF |
Additional relevant MeSH terms:
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Heart Diseases Vascular Diseases Cardiovascular Diseases Aspirin Fluconazole Substance P Neurokinin A Nitric Oxide Anti-Inflammatory Agents, Non-Steroidal Analgesics, Non-Narcotic Analgesics Sensory System Agents Peripheral Nervous System Agents Physiological Effects of Drugs Anti-Inflammatory Agents |
Antirheumatic Agents Fibrinolytic Agents Fibrin Modulating Agents Molecular Mechanisms of Pharmacological Action Platelet Aggregation Inhibitors Cyclooxygenase Inhibitors Enzyme Inhibitors Antipyretics Antifungal Agents Anti-Infective Agents 14-alpha Demethylase Inhibitors Cytochrome P-450 Enzyme Inhibitors Steroid Synthesis Inhibitors Hormone Antagonists Hormones, Hormone Substitutes, and Hormone Antagonists |
ClinicalTrials.gov processed this record on June 28, 2017