Effect of ions on the light-sensitive current in retinal rods

Nature. 1981 Aug 6;292(5823):502-5. doi: 10.1038/292502a0.


The effect of ions on the light-sensitive current of retinal rods was studied by sucking the inner segment into a tightly fitting capillary with the outer segment projecting into a flowing solution. This new method showed that the light-sensitive pathway, in which Na+ is the normal carrier of current, has an ionic selectivity different from that of other known sodium channels. Externàl calcium has a striking effect on the current, which increased about 20-fold when all calcium was removed. Reducing the sodium concentration gradient greatly prolonged the response to a flash of light, as would be expected if internal calcium blocks sodium channels and if light releases calcium which is subsequently extruded by a sodium-calcium exchange mechanism.

MeSH terms

  • Animals
  • Bufo marinus
  • Calcium / physiology
  • Electric Conductivity
  • In Vitro Techniques
  • Ion Channels / physiology
  • Light
  • Magnesium / physiology
  • Photoreceptor Cells / physiology*
  • Photoreceptor Cells / radiation effects
  • Sodium / physiology*


  • Ion Channels
  • Sodium
  • Magnesium
  • Calcium