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Mechanisms of Choroidal Blood Flow Changes During Dark/Light Transitions

This study has been completed.
Sponsor:
ClinicalTrials.gov Identifier:
NCT00431392
First Posted: February 5, 2007
Last Update Posted: February 5, 2007
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:
Medical University of Vienna
  Purpose

There is evidence from a variety of animal studies that choroidal blood flow is under neural control. By contrast, only little information is available from human studies. Recent results indicate that a light/dark transition is associated with a short lasting reduction in choroidal blood flow. We have shown that during unilateral dark/light transition both eyes react with choroidal vasoconstriction strongly indicating a neural mechanism.

The present studies investigate this possibility by using pharmacological interventions. The pharmacological agents tested include a nitric oxide synthase inhibitor, an alpha-receptor agonist (as a control substance for the blood pressure increasing nitric oxide synthase inhibitor), a muscarinic receptor blocker, and a non-specific beta-blocker. These drugs were chosen on the basis of previous animal experiments, as the systems, which are specifically influenced by these substances, are likely involved in neural control of choroidal blood flow.


Condition Intervention Phase
Regional Blood Flow Ocular Physiology Drug: Phenylephrine Drug: NG-Monomethyl-L-Arginine Drug: Propanolol Drug: Atropine Phase 2

Study Type: Interventional
Study Design: Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Double
Primary Purpose: Treatment
Official Title: Mechanisms of Choroidal Blood Flow Changes During Dark/Light Transitions

Further study details as provided by Medical University of Vienna:

Primary Outcome Measures:
  • choroidal blood flow
  • fundus pulsation amplitude

Estimated Enrollment: 42
Study Start Date: September 2001
  Eligibility

Information from the National Library of Medicine

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Ages Eligible for Study:   19 Years to 35 Years   (Adult)
Sexes Eligible for Study:   Male
Accepts Healthy Volunteers:   Yes
Criteria

Inclusion Criteria:

  • Men aged between 19 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 < 3 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 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
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): NCT00431392


Locations
Austria
Department of Clinical Pharmacology, Medical University of Vienna
Vienna, Austria, 1090
Sponsors and Collaborators
Medical University of Vienna
Investigators
Principal Investigator: Michael Wolzt, MD Department of Clinical Pharmacology, Medical University of Vienna
  More Information

ClinicalTrials.gov Identifier: NCT00431392     History of Changes
Other Study ID Numbers: OPHT-180601
First Submitted: February 2, 2007
First Posted: February 5, 2007
Last Update Posted: February 5, 2007
Last Verified: January 2007

Keywords provided by Medical University of Vienna:
Choroidal blood flow
NO-synthase
light/dark transition

Additional relevant MeSH terms:
Phenylephrine
Atropine
Oxymetazoline
Propranolol
omega-N-Methylarginine
Cardiotonic Agents
Mydriatics
Autonomic Agents
Peripheral Nervous System Agents
Physiological Effects of Drugs
Sympathomimetics
Vasoconstrictor Agents
Nasal Decongestants
Respiratory System Agents
Adrenergic alpha-1 Receptor Agonists
Adrenergic alpha-Agonists
Adrenergic Agonists
Adrenergic Agents
Neurotransmitter Agents
Molecular Mechanisms of Pharmacological Action
Protective Agents
Adjuvants, Anesthesia
Anti-Arrhythmia Agents
Bronchodilator Agents
Anti-Asthmatic Agents
Parasympatholytics
Muscarinic Antagonists
Cholinergic Antagonists
Cholinergic Agents
Adrenergic beta-Antagonists