Classification of potassium and chlorine ionic currents in retinal ganglion cell line (RGC-5) by whole-cell patch clamp.

Retinal ganglion cell line (RGC-5) has been widely used as a valuable model for studying pathophysiology and physiology of retinal ganglion cells in vitro. However, the electrophysiological characteristics, especially a thorough classification of ionic currents in the cell line, remain to be elucidated in details. In the present study, we determined the resting membrane potential (RMP) in RGC-5 cell line and then identified different types of ionic currents by using the whole-cell patch-clamp technique. The RMP recorded in the cell line was between -30 and -6 mV (-17.6 ± 2.6 mV, n = 10). We observed the following voltage-gated ion channel currents: (1) inwardly rectifying Cl- current (I Cl,ir), which could be blocked by Zn2+; (2) Ca2+-activated Cl- current (I Cl,Ca), which was sensitive to extracellular Ca2+ and could be inhibited by disodium 4,4'-diisothiocyanatostilbene-2,2'-disulfonate; (3) inwardly rectifying K+ currents (I K1), which could be blocked by Ba2+; (4) a small amount of delayed rectifier K+ current (I K). On the other hand, the voltage-gated sodium channels current (I Na) and transient outward potassium channels current (I A) were not observed in this cell line. These results further characterize the ionic currents in the RGC-5 cell line and are beneficial for future studies especially on ion channel (patho)physiology and pharmacology in the RGC-5 cell line.