title: Glutamate responses of bipolar cells in a slice preparation of the rat retina.
abstract: Whole-cell currents from >70 voltage-clamped bipolar cells were recorded in a slice preparation of the rat retina. The recorded cells were identified and classified by intracellular staining with Lucifer yellow. Glutamate, the specific agonists (+/-)-2-amino-4-phosphonobutyric acid (AP-4) and kainate (KA), and the antagonist 6-cyanoquinoxaline-2,3-dione (CNQX) were applied. The cells could be isolated from presynaptic influences by the co-application of bicuculline, strychnine, and cobalt ions. Responses to AP-4 were elicited only from bipolar cells with axons stratifying in the inner part of the inner plexiform layer (IPL). AP-4 caused an outward current in these cells attributable to the closure of nonspecific cation channels. Responses to kainate representing a direct action of the drug on the recorded cells were observed only in bipolar cells with axons stratifying in the outer part of the IPL. KA caused a CNQX-sensitive inward current in these cells, associated with openings of nonspecific cation channels. The results predict that cone bipolar (CB) cells with axons terminating in the outer IPL are OFF-bipolars, whereas those with axons terminating in the inner IPL are ON-bipolars. Most of the cells expressed GABA-gated Cl- conductances. In rod bipolar and in some CB cells, only part of the GABA-induced currents could be blocked by the application of bicuculline, suggesting the presence of GABAc receptors in addition to GABAA receptors.
authors.affiliation: Max-Planck-Institut für Hirnforschung, Frankfort, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Euler
authors.forename: H
authors.initials: H
authors.lastname: Schneider
authors.forename: H
authors.initials: H
authors.lastname: Wässle
mesh_terms: D018750:6-Cyano-7-nitroquinoxaline-2,3-dione / Q000494:pharmacology; D000613:Aminobutyrates / Q000494:pharmacology; D000818:Animals; D004553:Electric Conductivity; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D018698:Glutamic Acid / Q000378:metabolism*; D066298:In Vitro Techniques; D007608:Kainic Acid / Q000494:pharmacology; D051381:Rats; D012160:Retina / Q000166:cytology / Q000378:metabolism* / Q000502:physiology; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology
chemical_list: D000613:Aminobutyrates; D018690:Excitatory Amino Acid Agonists; D018691:Excitatory Amino Acid Antagonists; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; C012729:2-amino-4-phosphonobutyric acid; D007608:Kainic Acid