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Angiotensin levels in the eye
A H Danser1, F H Derkx, P J Admiraal
1Department of Pharmacology, Erasmus University, Rotterdam, The Netherlands.
Investigative Ophthalmology & Visual Science
|March 1, 1994
Summary
The eye generates angiotensin I and II locally within ocular tissues, not from blood circulation. This indicates a compartmentalized renin-angiotensin system (RAS) within the eye.
Area of Science:
- Ophthalmology
- Endocrinology
- Physiology
Background:
- Ocular tissues and fluids contain renin and prorenin at levels unexplained by blood admixture.
- The renin-angiotensin system (RAS) plays a crucial role in various physiological processes.
Purpose of the Study:
- To investigate the presence and origin of angiotensins I and II (ANG I and II) within the eye.
- To gather further evidence for a local RAS in ocular tissues.
Main Methods:
- Measurement of ANG I and II concentrations in porcine ocular tissues and fluids.
- Analysis of human aqueous, vitreous, and subretinal fluids.
- Infusion studies with radiolabeled ANG I in rabbits to assess blood-retinal barrier permeability.
Main Results:
- ANG I and II levels in normal porcine ocular tissues were significantly higher than attributable to blood contamination.
- ANG I and II were barely detectable in porcine vitreous fluid, with minimal ANG I entering the vitreous in rabbits.
- In human ocular fluids from diseased eyes, ANG I and II levels correlated with serum albumin, suggesting leakage from circulation when the blood-retinal barrier is compromised.
Conclusions:
- ANG I and II are primarily generated locally within ocular tissues.
- There is significant compartmentalization of the ocular RAS, with limited leakage into ocular fluids under normal conditions.
- These findings support the existence of an independent, local RAS within the eye.