Glutamate responses of bipolar cells in a slice preparation of the rat retina

J Neurosci. 1996 May 1;16(9):2934-44. doi: 10.1523/JNEUROSCI.16-09-02934.1996.


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.

MeSH terms

  • 6-Cyano-7-nitroquinoxaline-2,3-dione / pharmacology
  • Aminobutyrates / pharmacology
  • Animals
  • Electric Conductivity
  • Excitatory Amino Acid Agonists / pharmacology
  • Excitatory Amino Acid Antagonists / pharmacology
  • Glutamic Acid / metabolism*
  • In Vitro Techniques
  • Kainic Acid / pharmacology
  • Rats
  • Retina / cytology
  • Retina / metabolism*
  • Retina / physiology
  • gamma-Aminobutyric Acid / pharmacology


  • Aminobutyrates
  • Excitatory Amino Acid Agonists
  • Excitatory Amino Acid Antagonists
  • Glutamic Acid
  • gamma-Aminobutyric Acid
  • 6-Cyano-7-nitroquinoxaline-2,3-dione
  • 2-amino-4-phosphonobutyric acid
  • Kainic Acid