Single chloride channels in cultured rat neurones

Single-channel currents through chloride channels were recorded in cultured hippocampal neurones from rats using the patch-clamp method. The channel is active at voltages between -80 and +80 mV, and the time spent in the open state increases with depolarization (almost fourfold for 120 mV). The channel conductance is 62 pS in symmetrical 150 mM NaCl saline. In salt gradient conditions the channel was measurably permeable to Na+. Substitution of NO3- and Br- for Cl- gave higher single-channel currents, meaning a higher permeability of the channel toward the two anions than to Cl-. SO4(2-) ions were poorer charge carriers, yet contributed measurable inward current at negative voltages. Channel activity appeared independent of intracellular Ca2+ concentration. Taken together, these features would suggest for this channel a role in stabilizing resting membrane potential and in maintaining normal cell excitability.