Abstract
In the retina, adenosine is released in the dark and has been shown to inhibit Ca2+ influx through voltage-gated Ca2+ channels in cones. Therefore, we tested whether adenosine can inhibit exocytosis from isolated cone photoreceptors. Simultaneous measurements of membrane exocytosis and Ca2+ were made from cones using the activity-dependent dye, Synaptored-C2, and the Ca2+ indicator dye, Fluo-4. Adenosine suppressed exocytosis in cones, indicating that transmitter release is also reduced from cone terminals, and further supports an inhibitory mechanism for modulating transmitter release onto second-order neurons. Furthermore, this raises the possibility that adenosine might be neuroprotective for photoreceptors and second-order neurons by suppressing Ca2+ levels in cones and reducing exocytosis of L-glutamate, respectively.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
MeSH terms
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Adenosine / metabolism*
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Adenosine / pharmacology
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Ambystoma / anatomy & histology
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Ambystoma / metabolism*
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Aniline Compounds
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Animals
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Calcium Channels / drug effects
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Calcium Channels / metabolism
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Calcium Signaling / drug effects
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Calcium Signaling / physiology
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Cytoprotection / drug effects
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Cytoprotection / physiology
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Exocytosis / drug effects
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Exocytosis / physiology*
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Glutamic Acid / metabolism
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Indicators and Reagents
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Kinetics
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Neural Inhibition / drug effects
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Neural Inhibition / physiology
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Neurotransmitter Agents / metabolism
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Organ Culture Techniques
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Potassium / metabolism
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Potassium / pharmacology
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Presynaptic Terminals / drug effects
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Presynaptic Terminals / metabolism*
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Pyridinium Compounds
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Retinal Cone Photoreceptor Cells / drug effects
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Retinal Cone Photoreceptor Cells / metabolism*
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Retinal Cone Photoreceptor Cells / ultrastructure
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Synaptic Transmission / drug effects
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Synaptic Transmission / physiology*
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Vision, Ocular / drug effects
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Vision, Ocular / physiology
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Xanthenes
Substances
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Aniline Compounds
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Calcium Channels
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Fluo 4
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Indicators and Reagents
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N-(3-trimethylammoniumpropyl)-4-(6-(4-(diethylamino)phenyl)hexatrienyl)pyridinium
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Neurotransmitter Agents
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Pyridinium Compounds
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Xanthenes
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Glutamic Acid
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Adenosine
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Potassium