Mechanisms of Choroidal Blood Flow Changes During Dark/Light Transitions

This study has been completed.
Information provided by:
Medical University of Vienna Identifier:
First received: February 2, 2007
Last updated: NA
Last verified: January 2007
History: No changes posted

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
Endpoint Classification: Safety/Efficacy Study
Intervention Model: Crossover Assignment
Masking: Double-Blind
Primary Purpose: Treatment
Official Title: Mechanisms of Choroidal Blood Flow Changes During Dark/Light Transitions

Resource links provided by NLM:

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

Ages Eligible for Study:   19 Years to 35 Years
Genders Eligible for Study:   Male
Accepts Healthy Volunteers:   Yes

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
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Please refer to this study by its identifier: NCT00431392

Department of Clinical Pharmacology, Medical University of Vienna
Vienna, Austria, 1090
Sponsors and Collaborators
Medical University of Vienna
Principal Investigator: Michael Wolzt, MD Department of Clinical Pharmacology, Medical University of Vienna
  More Information Identifier: NCT00431392     History of Changes
Other Study ID Numbers: OPHT-180601 
Study First Received: February 2, 2007
Last Updated: February 2, 2007
Health Authority: Austria: Agency for Health and Food Safety

Keywords provided by Medical University of Vienna:
Choroidal blood flow
light/dark transition

Additional relevant MeSH terms:
Adrenergic Agents
Adrenergic Agonists
Adrenergic alpha-1 Receptor Agonists
Adrenergic alpha-Agonists
Autonomic Agents
Cardiotonic Agents
Enzyme Inhibitors
Molecular Mechanisms of Pharmacological Action
Nasal Decongestants
Neurotransmitter Agents
Peripheral Nervous System Agents
Physiological Effects of Drugs
Protective Agents
Respiratory System Agents
Vasoconstrictor Agents processed this record on May 26, 2016