Role of Endothelin- and Nitric Oxide-System in the Regulation of Optic Nerve Head Blood Flow During Changes in Ocular Perfusion Pressure
The recruitment status of this study is unknown because the information has not been verified recently.
Verified June 2009 by Medical University of Vienna.
Recruitment status was Recruiting
Recruitment status was Recruiting
Sponsor:
Medical University of Vienna
Information provided by:
Medical University of Vienna
ClinicalTrials.gov Identifier:
NCT00406731
First received: November 30, 2006
Last updated: June 2, 2009
Last verified: June 2009
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Purpose
Autoregulation is the ability of a vascular bed to maintain blood flow despite changes in perfusion pressure. The existence of an effective autoregulation in the optic nerve circulation has been shown in animals and humans. The exact mechanism behind this autoregulation is still unknown. The motive for the investigation of optic nerve head (ONH) blood flow autoregulation is to enhance the understanding of pathologic eye conditions associated with ocular vascular disorders. To clarify the regulatory mechanisms of ONH microcirculation is of critical importance to understand the pathophysiology of glaucoma because there is evidence that glaucoma is associated with optic nerve head ischemia. Several studies indicate that a disturbed autoregulation might contribute to glaucomatous optic neuropathy. Previous findings suggest endothelial dysfunction in glaucomatous optic neuropathy, in particular alterations in endothelin- and nitric oxide- system, which both play an important role in local regulation of vascular tone.
In the present study, changes in ocular perfusion pressure will be performed during administration of drugs, which may potentially alter the pressure-flow relationship. These drugs include endothelin-1 and the nitric oxide synthase inhibitor NG-monomethyl-L-arginine (L-NMMA).
| Condition | Intervention | Phase |
|---|---|---|
|
Ocular Physiology Optic Disk Regional Blood Flow |
Drug: NG-monomethyl-L-arginine (L-NMMA) Drug: Endothelin-1 (ET-1) Drug: Physiologic saline solution (placebo control) Device: Laser Doppler flowmetry Device: Goldmann applanation tonometer Device: HP-CMS patient monitor Procedure: Suction cup method |
Phase 2 |
| Study Type: | Interventional |
| Study Design: | Allocation: Randomized Endpoint Classification: Safety/Efficacy Study Intervention Model: Crossover Assignment Masking: Double Blind (Subject, Investigator, Outcomes Assessor) Primary Purpose: Treatment |
| Official Title: | Role of Endothelin-and Nitric Oxide-System in the Regulation of Optic Nerve Head Blood Flow During Changes in Ocular Perfusion Pressure |
Resource links provided by NLM:
Further study details as provided by Medical University of Vienna:
Primary Outcome Measures:
- ONH pressure-flow relationship [ Time Frame: in total 6x on 3 study days ] [ Designated as safety issue: No ]
| Estimated Enrollment: | 18 |
| Study Start Date: | January 2008 |
| Estimated Study Completion Date: | November 2009 |
| Estimated Primary Completion Date: | October 2009 (Final data collection date for primary outcome measure) |
Intervention Details:
-
Drug: NG-monomethyl-L-arginine (L-NMMA)
bolus 6 mg/kg over 5 minutes followed by a continuous intravenous infusion of 60 µg/kg/min over 12 minutes; twice on 1 study day
Drug: Endothelin-1 (ET-1)
5 ng/kg/min intravenous infusion over 17 minutes; twice on 1 study day
Drug: Physiologic saline solution (placebo control)
intravenous infusion over 20 minutes; twice on 1 study day
Device: Laser Doppler flowmetry
blood flow measurements at the temporal neuroretinal rim of the optic nerve head
Device: Goldmann applanation tonometer
Intraocular pressure measurements
Device: HP-CMS patient monitor
blood pressure and pulse rate measurements
Procedure: Suction cup method
The IOP will be raised by an 11 mm diameter, standardized suction cup placed on the temporal sclera with the anterior edge at least 1 mm from the limbus.
Eligibility| Ages Eligible for Study: | 18 Years to 35 Years |
| Genders Eligible for Study: | Male |
| Accepts Healthy Volunteers: | Yes |
Criteria
Inclusion Criteria:
- Men aged between 18 and 35 years, nonsmokers
- Body mass index between 15th and 85th percentile (Must et al. 1991)
- Normal findings in the medical history and physical examination unless the investigator considers an abnormality to be clinically irrelevant
- Normal laboratory values unless the investigator considers an abnormality to be clinically irrelevant
- Normal ophthalmic findings, ametropy < 1 Dpt
Exclusion Criteria:
- Regular use of medication, abuse of alcoholic beverages, participation in a clinical trial in the 3 weeks preceding the study
- Treatment in the previous 3 weeks with any drug
- Symptoms of a clinically relevant illness in the 3 weeks before the first study day
- History of hypersensitivity to the trial drug or to drugs with a similar chemical structure
- History or presence of systemic or pulmonary hypertension, or other cardiac or pulmonary diseases
- History or presence of gastrointestinal, liver or kidney disease, or other conditions known to interfere with, distribution, metabolism or excretion of study drugs
- Blood donation during the previous 3 weeks
Contacts and Locations
Please refer to this study by its ClinicalTrials.gov identifier: NCT00406731
Contacts
| Contact: Gerhard Garhoefer, MD | +43 40 400 2981 | gerhard.garhoefer@meduniwien.ac.at |
Locations
| Austria | |
| Department of Clinical Pharmacology, Medical University of Vienna | Recruiting |
| Vienna, Austria, 1090 | |
Sponsors and Collaborators
Medical University of Vienna
Investigators
| Principal Investigator: | Gabriele Fuchsjaeger-Mayrl, MD,Univ.Doz. | Department of Clinical Pharmacology, Medical University of Vienna |
More Information
No publications provided
| Responsible Party: | Gabriele Fuchsjaeger-Mayrl, MD, Department of Clinical Pharmacology, Medical University of Vienna |
| ClinicalTrials.gov Identifier: | NCT00406731 History of Changes |
| Other Study ID Numbers: | OPHT-080206 |
| Study First Received: | November 30, 2006 |
| Last Updated: | June 2, 2009 |
| Health Authority: | Austria: Agency for Health and Food Safety |
Keywords provided by Medical University of Vienna:
|
Endothelin-1 L-NG-Monomethyl Arginine Optic Nerve Head blood flow |
Additional relevant MeSH terms:
|
Nitric Oxide Omega-N-Methylarginine Bronchodilator Agents Autonomic Agents Peripheral Nervous System Agents Physiological Effects of Drugs Pharmacologic Actions Anti-Asthmatic Agents Respiratory System Agents Therapeutic Uses |
Free Radical Scavengers Antioxidants Molecular Mechanisms of Pharmacological Action Neurotransmitter Agents Endothelium-Dependent Relaxing Factors Vasodilator Agents Cardiovascular Agents Protective Agents Enzyme Inhibitors |
ClinicalTrials.gov processed this record on May 23, 2013