A cGMP-gated current can control exocytosis at cone synapses

The voltage-gated Ca 2+ current in cone photoreceptors operates over only a small part of the physiological voltage range produced by light and, consequently, appears insufficient for controlling transmitter release. We have used a whole-cell voltage clamp to measure membrane current and the capacit...

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Bibliographic Details
Published inNeuron (Cambridge, Mass.) Vol. 13; no. 4; pp. 863 - 873
Main Authors Rieke, F., Schwartz, E.A.
Format Journal Article
LanguageEnglish
Published United States Elsevier Inc 1994
Subjects
Ambystoma
Animals
Calcium Channels - physiology
Cyclic GMP - pharmacology
Cyclic Nucleotide-Gated Cation Channels
Electric Conductivity
Exocytosis - physiology
Ion Channel Gating - drug effects
Ion Channels - physiology
Membrane Potentials
Photoreceptor Cells - physiology
Retina - physiology
Retinal Rod Photoreceptor Cells - physiology
Synapses - physiology
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Summary:The voltage-gated Ca 2+ current in cone photoreceptors operates over only a small part of the physiological voltage range produced by light and, consequently, appears insufficient for controlling transmitter release. We have used a whole-cell voltage clamp to measure membrane current and the capacitance change produced by exocytosis in solitary cone and rod photoreceptors isolated from the salamander retina. I n both types of photoreceptor, Ca 2+ influx through voltage-gated Ca 2+ channels initiated exocytosis. In addition, Ca 2+ influx through a cGMP-gated channel in the inner segment and synaptic processes of cones also initiated exocytosis. The cGMP-gated current sustained exocytosis over the entire physiological voltage range.
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ISSN:0896-6273
1097-4199
DOI:10.1016/0896-6273(94)90252-6