Permeation of calcium ions through non-NMDA glutamate channels in retinal bipolar cells

Science. 1991 Mar 29;251(5001):1613-5. doi: 10.1126/science.1849316.


The conduction of calcium ions through glutamate-gated channels is important in the induction of long-term potentiation and may trigger other cellular changes. In retinal bipolar cells, which lack the N-methyl-D-aspartate (NMDA) type of glutamate-gated channel, calcium permeability through non-NMDA channels was examined. Changes in extracellular calcium concentration unexpectedly affected the reversal potential for glutamate-induced currents in a manner consistent with these channels being highly permeable to calcium. External magnesium ions promote desensitization of these non-NMDA channels in a voltage-independent way. Thus, in addition to non-NMDA channels that conduct only sodium and potassium, there is a class that is also permeable to calcium.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Ambystoma
  • Animals
  • Calcium / metabolism*
  • Calcium / pharmacology
  • Calcium Channels / drug effects
  • Calcium Channels / physiology*
  • Cell Membrane Permeability
  • Glutamates / physiology
  • In Vitro Techniques
  • Kainic Acid / pharmacology
  • Membrane Potentials / drug effects
  • N-Methylaspartate / pharmacology
  • Receptors, Glutamate
  • Receptors, N-Methyl-D-Aspartate / physiology
  • Receptors, Neurotransmitter / drug effects
  • Receptors, Neurotransmitter / physiology*
  • Retina / cytology
  • Retina / physiology*


  • Calcium Channels
  • Glutamates
  • Receptors, Glutamate
  • Receptors, N-Methyl-D-Aspartate
  • Receptors, Neurotransmitter
  • N-Methylaspartate
  • Kainic Acid
  • Calcium