Mechanisms of Choroidal Blood Flow Changes During Dark/Light Transitions - Full Text View

Sponsor:	Medical University of Vienna
Information provided by:	Medical University of Vienna
ClinicalTrials.gov Identifier:	NCT00431392

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 II

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:

Drug Information available for: Atropine Phenylephrine Phenylephrine hydrochloride omega-N-Methylarginine Arginine Propranolol hydrochloride Propranolol Oxymetazoline Oxymetazoline hydrochloride Dexpropranolol Atropine sulfate

U.S. FDA Resources

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

Ages Eligible for Study:	19 Years to 35 Years
Genders 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

Please refer to this study by its ClinicalTrials.gov identifier: 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

No publications provided

ClinicalTrials.gov 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
NO-synthase
light/dark transition

Additional relevant MeSH terms:

Atropine
Propranolol
Phenylephrine
Oxymetazoline
Omega-N-Methylarginine
Adjuvants, Anesthesia
Central Nervous System Agents
Therapeutic Uses
Pharmacologic Actions
Anti-Arrhythmia Agents
Cardiovascular Agents
Bronchodilator Agents
Autonomic Agents
Peripheral Nervous System Agents
Physiological Effects of Drugs

Anti-Asthmatic Agents
Respiratory System Agents
Mydriatics
Parasympatholytics
Muscarinic Antagonists
Cholinergic Antagonists
Cholinergic Agents
Neurotransmitter Agents
Molecular Mechanisms of Pharmacological Action
Antihypertensive Agents
Adrenergic beta-Antagonists
Adrenergic Antagonists
Adrenergic Agents
Vasodilator Agents
Adrenergic alpha-1 Receptor Agonists

ClinicalTrials.gov processed this record on February 09, 2012