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Role of Endothelin-1 in Optic Nerve Head Blood Flow Regulation During Isometric Exercise in Healthy Humans

This study has been completed.
Sponsor:
ClinicalTrials.gov Identifier:
NCT00915070
First Posted: June 5, 2009
Last Update Posted: August 10, 2012
The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details.
Information provided by (Responsible Party):
Gerhard Garhofer, Medical University of Vienna
  Purpose

Autoregulation is defined as the ability of a vascular bed to adapt its vascular resistance to changes in perfusion pressure. In the eye, several studies have reported that retinal blood flow is autoregulated over a wide range of ocular perfusion pressures. The investigators could recently show that Endothelin-1 is a key metabolite in the regulation of vascular tone in the eye and plays an important role in the blood flow autoregulation of the choroidal circulation. However, no data is yet available for the optic nerve head. Thus, the present study is designed to test the hypothesis that Endothelin-1 plays also a role in optic nerve head blood flow autoregulation.

Therefore, subjects will perform squatting to increase systemic perfusion pressure during administration of either an endothelin A-receptor blocker (BQ-123) or placebo. Optic nerve head blood flow will be continuously measured during the procedure to investigate optic nerve head autoregulation.


Condition Intervention
Healthy Drug: BQ-123 Drug: Physiological saline solution Device: Laser Doppler Flowmetry Device: Goldmann Applanation Tonometer Other: squatting

Study Type: Interventional
Study Design: Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Triple (Participant, Investigator, Outcomes Assessor)
Primary Purpose: Basic Science
Official Title: Role of Endothelin-1 in Optic Nerve Head Blood Flow Regulation During Isometric Exercise in Healthy Humans

Resource links provided by NLM:


Further study details as provided by Gerhard Garhofer, Medical University of Vienna:

Primary Outcome Measures:
  • Optic nerve head pressure-flow relationship [ Time Frame: 1 year ]

Enrollment: 16
Study Start Date: October 2010
Study Completion Date: December 2011
Primary Completion Date: May 2011 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Active Comparator: BQ-123 Drug: BQ-123
60 mcg/min, infusion period: 60 min
Drug: Physiological saline solution
infusion period 60 minutes
Device: Laser Doppler Flowmetry
blood flow measurements at the temporal neuroretinal rim to assess optic nerve head blood flow
Device: Goldmann Applanation Tonometer
intraocular pressure measurements
Other: squatting
subjects will perform squatting for 6 minutes while blood flow measurements
Placebo Comparator: Physiological saline solution Drug: BQ-123
60 mcg/min, infusion period: 60 min
Drug: Physiological saline solution
infusion period 60 minutes
Device: Laser Doppler Flowmetry
blood flow measurements at the temporal neuroretinal rim to assess optic nerve head blood flow
Device: Goldmann Applanation Tonometer
intraocular pressure measurements
Other: squatting
subjects will perform squatting for 6 minutes while blood flow measurements

  Eligibility

Information from the National Library of Medicine

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Ages Eligible for Study:   18 Years to 35 Years   (Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes
Criteria

Inclusion Criteria:

  • Men and women aged between 18 and 35 years, nonsmokers
  • Men and women will be included in equal parts
  • Normal findings in the medical history and physical examination unless the investigator considers an abnormality to be clinically irrelevant
  • Normal findings in the laboratory testings unless the investigator considers an abnormality to be clinically irrelevant
  • Normal ophthalmic findings, ametropia less than 3 diopters

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 (except intake of oral contraceptives)
  • Symptoms of a clinically relevant illness in the 3 weeks before the first study day
  • 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
  • Pregnancy
  Contacts and Locations
Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT00915070


Locations
Austria
Department of Clinical Pharmacology, Medical University of Vienna
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

Responsible Party: Gerhard Garhofer, Ass.Prof.Priv.Doz.Dr., Medical University of Vienna
ClinicalTrials.gov Identifier: NCT00915070     History of Changes
Other Study ID Numbers: OPHT-320708
First Submitted: June 1, 2009
First Posted: June 5, 2009
Last Update Posted: August 10, 2012
Last Verified: August 2012

Keywords provided by Gerhard Garhofer, Medical University of Vienna:
BQ-123
Optic Nerve Head Blood Flow
Intraocular Pressure
Regional Blood Flow
Ocular Physiology
Optic Disk

Additional relevant MeSH terms:
cyclo(Trp-Asp-Pro-Val-Leu)
Antihypertensive Agents
Endothelin Receptor Antagonists
Molecular Mechanisms of Pharmacological Action