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Effects of adenosine on ocular blood flow
M Portellos1, C E Riva, S D Cranstoun
1Scheie Eye Institute, University of Pennsylvania, Philadelphia 19104, USA.
Investigative Ophthalmology & Visual Science
|August 1, 1995
Summary
Intravenous adenosine increased choroidal blood flow but did not affect optic nerve head or retinal blood flow in cats. This suggests a barrier limits adenosine
Area of Science:
- Ophthalmology
- Cardiovascular Physiology
- Neuroscience
Background:
- Adenosine plays a role in regulating blood flow.
- The blood-brain barrier restricts adenosine's access to the brain.
- The presence of a similar barrier in the eye is unknown.
Purpose of the Study:
- To investigate the impact of intravascular adenosine on ocular fundus blood flow.
- To determine if the eye possesses a barrier to adenosine similar to the blood-brain barrier.
Main Methods:
- Noninvasive techniques including laser Doppler flowmetry and velocimetry were employed.
- Fundus photography was used to assess changes in blood flow.
- Adenosine was administered via intravenous infusions at specific dosages.
Main Results:
- Intravenous adenosine significantly increased choroidal blood flow (by 60% at 0.6 mg/kg per minute).
- No significant changes were observed in optic nerve head blood flow.
- Retinal blood flow remained unaffected by adenosine infusions.
Conclusions:
- The lack of effect on optic nerve and retinal circulations suggests a barrier, likely tight junctions, prevents adenosine access to receptors.
- Perivascular adenosine in the choroid is the probable cause of increased choroidal blood flow.
- The findings imply a differential barrier function within the ocular vasculature.