Zinc reduces low-threshold Ca2+ currents of rat thalamic relay neurons

Whole-cell voltage-clamping of thalamic relay neurons was used to examine the possibility of a Zn2+-mediated reduction of the low-threshold transient Ca2+ current (IT) of a central element in thalamocortical oscillations. We found that Zn2+ reversibly decreased IT in it concentration-dependent manner (IC50 = 55 muM), mainly by reducing the number of IT channels available for activation. Zn2+ did not affect the reaction kinetics, but did affect the voltage-dependence of IT channel gating. However, the apparent alterations in gating properties were not enough to account for the huge IT reduction. (C) 2003 Elsevier Ireland Ltd and the Japan Neuroscience Society. All rights reserved.