title: Intracellular cesium separates two glutamate conductances in retinal bipolar cells of goldfish.
abstract: The responses of depolarizing bipolar cells to glutamate were investigated in the superfused isolated goldfish retina. In intracellular recordings with potassium-filled microelectrodes, glutamate hyperpolarized cells but did not alter the net input conductance. In recordings with cesium-filled microelectrodes, the glutamate-evoked hyperpolarization was associated with a net conductance decrease. In the presence of internal cesium, glutamate action had the same reversal potential as the actions of the glutamate analog 2-amino-4-phosphonobutyrate (APB) and the rod transmitter, suggesting that all three of these substances act at the same class of receptor. We propose that glutamate acts both at the APB-sensitive receptor that mediates rod inputs and at another receptor type that produces a conductance increase, is blocked by cesium, and may mimic the action of the cone transmitter.
authors.affiliation: Department of Ophthalmology, University of California, San Fransciso 94143-0730.
authors.forename: S
authors.initials: S
authors.lastname: Nawy
authors.forename: D R
authors.initials: DR
authors.lastname: Copenhagen
mesh_terms: D000613:Aminobutyrates / Q000494:pharmacology; D000818:Animals; D002586:Cesium / Q000494:pharmacology; D003530:Cyprinidae / Q000502:physiology*; D005971:Glutamates / Q000494:pharmacology*; D006054:Goldfish / Q000502:physiology*; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D009474:Neurons / Q000502:physiology; D018377:Neurotransmitter Agents / Q000502:physiology; D012160:Retina / Q000502:physiology*
chemical_list: D000613:Aminobutyrates; D005971:Glutamates; D018377:Neurotransmitter Agents; D002586:Cesium; C012729:2-amino-4-phosphonobutyric acid