Role of Endothelin- and Nitric Oxide-system in the Regulation of Optic Nerve Head Blood Flow During Changes in Ocular Perfusion Pressure

August 13, 2019 updated by: Gerhard Garhofer, Medical University of Vienna

Role of endothelin-and Nitric Oxide-system in the Regulation of Optic Nerve Head Blood Flow During Changes in Ocular Perfusion Pressure

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).

Study Overview

Status

Withdrawn

Conditions

Intervention / Treatment

Study Type

Interventional

Phase

  • Phase 2

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Austria
      • Vienna, Austria, 1090
        • Department of Clinical Pharmacology, Medical University of Vienna

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years to 35 years (Adult)

Accepts Healthy Volunteers

Yes

Genders Eligible for Study

Male

Description

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

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Crossover Assignment
  • Masking: Triple

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Time Frame
ONH pressure-flow relationship
Time Frame: up to 3 study days
up to 3 study days

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Medical University of Vienna

Investigators

  • Principal Investigator: Gabriele Fuchsjaeger-Mayrl, MD,Univ.Doz., Department of Clinical Pharmacology, Medical University of Vienna

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start

January 1, 2008

Primary Completion (Actual)

November 1, 2014

Study Completion (Actual)

November 1, 2014

Study Registration Dates

First Submitted

November 30, 2006

First Submitted That Met QC Criteria

November 30, 2006

First Posted (Estimate)

December 4, 2006

Study Record Updates

Last Update Posted (Actual)

August 15, 2019

Last Update Submitted That Met QC Criteria

August 13, 2019

Last Verified

August 1, 2019

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • OPHT-080206

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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