Ionic currents of cultured horizontal cells isolated from white perch retina

J Neurophysiol. 1986 Mar;55(3):499-513. doi: 10.1152/jn.1986.55.3.499.


Horizontal cells from the retinas of white perch were isolated and maintained in cell culture for 3 days to 3 wk. Four morphologically distinct types of horizontal cells could be identified in culture and were labeled types H1, H2, H3, and H4. Whole-cell patch-clamp techniques were used to study the ionic currents present in the four cell types. In all cells, depolarizing commands above threshold elicited a fast-inward current followed by an outward current. The fast-inward current was abolished by tetrodotoxin (TTX) or 0 Na+ Ringer's, indicating the current was carried by Na+. In H1, H2, and H3 cells, the outward current, carried by K+, consisted of two components: a transient current (IA), blockable with 4-aminopyridine (4-AP), tetraethylammonium (TEA), or intracellular cesium and a sustained current that could be blocked with TEA. The H4 cell had only the sustained current. An inward rectifying K+ current (anomalous rectifier) was observed in the four cell types. The current was sensitive to the extracellular K+ concentration. Its activation showed two components: an instantaneous component and a slower component. The slow component becomes faster with greater hyperpolarizations. The four cell types possessed a small, sustained Ca2+ current that, under normal conditions, was masked by the inward Na+ current and outward K+ currents.

Publication types

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

MeSH terms

  • Action Potentials
  • Animals
  • Calcium / metabolism
  • Electric Stimulation
  • Electrophysiology
  • Fishes / metabolism*
  • In Vitro Techniques
  • Interneurons / cytology
  • Interneurons / metabolism*
  • Ion Channels / metabolism*
  • Potassium / metabolism
  • Retina / cytology
  • Retina / metabolism*
  • Sodium / metabolism


  • Ion Channels
  • Sodium
  • Potassium
  • Calcium