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Quantal Amplitude At The Cone Ribbon Synapse Can Be Adjusted By Changes In Cytosolic Glutamate., Theodore M. Bartoletti, Wallace B. Thoreson
Quantal Amplitude At The Cone Ribbon Synapse Can Be Adjusted By Changes In Cytosolic Glutamate., Theodore M. Bartoletti, Wallace B. Thoreson
Journal Articles: Ophthalmology
PURPOSE: Vision is encoded at photoreceptor synapses by the number of released vesicles and size of the post-synaptic response. We hypothesized that elevating cytosolic glutamate could enhance quantal size by increasing glutamate in vesicles.
METHODS: We introduced glutamate (10-40 mM) into cone terminals through a patch pipette and recorded excitatory post-synaptic currents (EPSCs) from horizontal or OFF bipolar cells in the Ambystoma tigrinum retinal slice preparation.
RESULTS: Elevating cytosolic glutamate in cone terminals enhanced EPSCs as well as quantal miniature EPSCs (mEPSCs). Enhancement was prevented by inhibiting vesicular glutamate transport with 1S,3R-1-aminocyclopentane-1,3-dicarboxylate in the patch pipette. A low affinity glutamate …