Zinc reduces low-threshold Ca 2+ currents of rat thalamic relay neurons

Abstract

Whole-cell voltage-clamping of thalamic relay neurons was used to examine the possibility of a Zn 2+-mediated reduction of the low-threshold transient Ca 2+ current ( I T) of a central element in thalamocortical oscillations. We found that Zn 2+ reversibly decreased I T in a concentration-dependent manner (IC 50=55 μM), mainly by reducing the number of I T channels available for activation. Zn 2+ did not affect the reaction kinetics, but did affect the voltage-dependence of I T channel gating. However, the apparent alterations in gating properties were not enough to account for the huge I T reduction.