Calcium-activated potassium current in single Novikoff cell

The electrophysical properties of the hemichannels of the gap junction in a single Novikoff cell was studied using patch-clamp whole-cell recording techniques. During the experiments, a transient outward current (peak current, I-p) was found to be evoked by the increment of depolarized pulses. I-p was voltage-dependent and could be inhibited partly by CsCl and tetraethylammonium (TEA), but was blocked completely by quinidine. When the intracellular free Ca2+ concentration ([Ca2+](i)) was increased, the amplitude of I-p was enhanced. Adding 10 nmol/l EGTA in the pipette solution, I-p disappeared. When cells were bathed in symmetrical high-K+ solution, I-p also completely disappeared. These results suggests that I-p is a calcium-activated potassium current, although it cannot be blocked by apamin. (C) 2001 Prous Science. All rights reserved.