Abstract | PURPOSE: To investigate the regulatory mechanisms responsible for autoregulation of retinal blood flow (RBF) during periods of decreased ocular perfusion pressure ( OPP). METHODS: RESULTS: Following PBS injection, the flow velocity decreased in proportion to the decrease in OPP; however, the retinal arteriolar diameter gradually increased. Consequently, the RBF was maintained near baseline levels when the OPP exceeded 70 mm Hg but decreased significantly (P < 0.01) when the OPP fell to less than or equal to 60 mm Hg due to elevated IOP or systemic hypotension. Adenosine receptor blocker 8-(p-sulfophenyl)theophylline, significantly (P < 0.01) enhanced decreases in RBF induced by elevated IOP and systemic hypotension at OPP from 80 to 40 mm Hg, whereas NO synthase inhibitor N(G)-nitro-L-arginine-methyl ester and NMDA receptor antagonist DL-2-amino-5-phosphonopentanoic acid only significantly (P < 0.01) enhanced reductions in RBF induced by elevated IOP. CONCLUSIONS: These results indicate that adenosine contributes to autoregulation of RBF during systemic hypotension, whereas adenosine, NO, and NMDA receptors autoregulate the RBF after elevated IOP. Different vasoregulatory factors might contribute to autoregulation of RBF after decreases in OPP induced by elevated IOP and systemic hypotension.
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Authors | Tomofumi Tani, Taiji Nagaoka, Seigo Nakabayashi, Takafumi Yoshioka, Akitoshi Yoshida |
Journal | Investigative ophthalmology & visual science
(Invest Ophthalmol Vis Sci)
Vol. 55
Issue 1
Pg. 360-7
(Jan 20 2014)
ISSN: 1552-5783 [Electronic] United States |
PMID | 24302588
(Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't)
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Chemical References |
- Endothelium-Dependent Relaxing Factors
- Excitatory Amino Acid Agonists
- Vasodilator Agents
- Nitric Oxide
- N-Methylaspartate
- Adenosine
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Topics |
- Adenosine
(administration & dosage)
- Animals
- Cats
- Disease Models, Animal
- Endothelium-Dependent Relaxing Factors
(administration & dosage)
- Excitatory Amino Acid Agonists
(administration & dosage)
- Female
- Homeostasis
- Hypotension
(physiopathology)
- Intraocular Pressure
(drug effects, physiology)
- Intravitreal Injections
- Laser-Doppler Flowmetry
- Male
- N-Methylaspartate
(administration & dosage)
- Nitric Oxide
(administration & dosage)
- Ocular Hypertension
(physiopathology)
- Regional Blood Flow
(drug effects, physiology)
- Retina
(drug effects, physiopathology)
- Vasodilator Agents
(administration & dosage)
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