An outwardly rectifying K+ current active near resting potential in human retinal pigment epithelial cells

• DOI: 10.1152/ajpcell.1995.269.1.c179
• Publication Date: 2017-12-24T18:32:45Z
• Authors: B. A. Hughes; M. Takahira; Y. Segawa
• Keywords: Tetraethylammonium; Reversal potential

Currents in freshly dissociated adult human retinal pigment epithelial (RPE) cells were studied using the perforated patch-clamp technique. The zero-current potential (V0) averaged -48.9 +/- 7.7 mV (n = 50). Depolarizing voltage pulses from -70 evoked an outward current that activated with first-order kinetics and did not inactivate during prolonged depolarizations. Repolarizing membrane produced tail currents reversed near K+ equilibrium potential, indicating sustained was carried mainly by K+. outwardly rectifying conductance (gK) had activation threshold -60 half-maximal at -37 mV. Approximately 25% of gK active average V0. nearly completely blocked 2 mM Ba2+ but relatively insensitive to 20 tetraethylammonium. kinetics, dependence, blocker sensitivity this clearly distinguish it delayed rectifier previously identified RPE cells. We conclude may help establish resting apical and/or basolateral membranes also participate transport across RPE.