A-current in rat globus pallidus: a whole-cell voltage clamp study on acutely dissociated neurons.

Globus pallidus neurons were dissociated from adult rats and recorded in whole-cell voltage-clamp mode. In tetrodotoxin- and cadmium-added bath, outward potassium conductances were evaluated. Depolarization activated large and predominantly sustained currents, with little inactivation. The transient outward current was isolated through its voltage-dependency, kinetics and pharmacology. A-like current activated around -45 mV and decayed exponentially with a time-constant of about 50 ms at 0 mV. Steady-state half-inactivation voltage was about -60 mV, suggesting that A-current was not fully inactivated at rest. 4-Aminopyridine sensitivity of the transient outward current was in the low millimolar range. A-current might play a relevant role in shaping firing properties of pallidal neurons.