Calcium and calcium-dependent chloride currents generate action potentials in solitary cone photoreceptors

Neuron. 1988 Aug;1(6):503-15. doi: 10.1016/0896-6273(88)90181-x.


Vertebrate rod and cone photoreceptors hyperpolarize when illuminated. However, synaptic input from horizontal cells can depolarize cones and even elicit action potentials. Using the whole-cell tight-seal recording technique, we determined that, in solitary cones isolated from a lizard retina, action potentials can be generated by depolarizing current steps under conditions where only two ionic currents are activated. A dihydropyridine-sensitive, inward Ca2+ current that activates at potentials positive to -40 mV can regeneratively depolarize the cell. Subsequently, a SITS-sensitive, Ca2(+)-dependent outward Cl- current repolarizes the cell. We suggest that these ionic currents may help explain lateral inhibition in the retina.

Publication types

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

MeSH terms

  • Action Potentials / drug effects
  • Animals
  • Calcium / pharmacology*
  • Calcium Channel Blockers / pharmacology
  • Calcium Channels / physiology*
  • Chloride Channels
  • Chlorides / physiology*
  • Electric Conductivity
  • In Vitro Techniques
  • Ion Channels / drug effects
  • Ion Channels / physiology*
  • Kinetics
  • Lizards
  • Membrane Proteins / physiology*
  • Photoreceptor Cells / physiology*
  • Tetraethylammonium
  • Tetraethylammonium Compounds / pharmacology


  • Calcium Channel Blockers
  • Calcium Channels
  • Chloride Channels
  • Chlorides
  • Ion Channels
  • Membrane Proteins
  • Tetraethylammonium Compounds
  • Tetraethylammonium
  • Calcium