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Role of Adenosine in the Control of Choroidal Blood Flow During Changes in Ocular Perfusion Pressure.

This study has been completed.
Study NCT00712764.   Last updated on July 8, 2008.   Information provided by Medical University of Vienna

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Descriptive Information Fields
Brief Title  Role of Adenosine in the Control of Choroidal Blood Flow During Changes in Ocular Perfusion Pressure.
Official Title  Role of Adenosine in the Control of Choroidal Blood Flow During Changes in Ocular Perfusion Pressure.
Brief Summary

Autoregulation is the ability of a vascular bed to maintain blood flow despite changes in perfusion pressure. For a long time it had been assumed that the choroid is a strictly passive vascular bed, which shows no autoregulation. However, recently several groups have identified some autoregulatory capacity of the human choroid. In the brain and the retina the mechanism behind autoregulation is most likely linked to changes in transmural pressure. In this model arterioles change their vascular tone depending on the pressure inside the vessel and outside the vessel. In the choroid, several observations argue against a direct involvement of arterioles. However, the mechanism behind choroidal autoregulation remains unclear. Adenosine, an endogenous purine metabolic end product with a potent vasodilatory effect on multiple vascular beds, leads to an increase in retinal and choroidal vessel diameter. The present study aims to investigate whether adenosine plays a role in choroidal autoregulation during a decrease in ocular perfusion pressure, which will be achieved by an increase in intraocular pressure.

Pressure/flow relationships will be investigated in the absence and presence of adenosine.

Detailed Description
Study Phase
Study Type  Interventional
Study Design  Treatment, Randomized, Double Blind (Subject, Investigator), Placebo Control, Crossover Assignment, Safety/Efficacy Study
Primary Outcome Measure  choroidal pressure-flow relationship [ Time Frame: 2 hours at 2 study days ] [ Designated as safety issue: No ]
Secondary Outcome Measure 
Condition  Ocular Physiology
Microcirculation
Intervention  Drug: Adenosine
Drug: Placebo
MEDLINE PMIDs
Links
Recruitment Information Fields
Recruitment Status  Completed
Enrollment  20
Start Date  January 2005
Completion Date April 2005
Eligibility Criteria 

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, ametropia < 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
Gender Male
Ages 18 Years to 35 Years
Accepts Healthy Volunteers Yes
Contacts ††
Location Countries  Austria
Administrative Information Fields
NCT ID  NCT00712764
Organization ID OPHT-011206
Secondary IDs ††
Study Sponsor  Medical University of Vienna
Collaborators ††
Investigators 
Principal Investigator:     Michael Wolzt, MD     Department of Clinical Pharmacology, Medical University of Vienna    
Information Provided By Medical University of Vienna
Verification Date December 2006
First Received Date  July 8, 2008
Last Updated Date July 8, 2008

 †    Required WHO trial registration data element.
††   WHO trial registration data element that is required only if it exists.




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