Kainate-induced inhibition of voltage-activated potassium currents in cultured chick telencephalic neurons.

Kainate indirectly produces an inhibition of voltage-activated outward potassium currents on cultured chick telencephalic neurons, besides directly evoking activation of AMPA/kainate receptors (current with linear I-V curve, reversal potential near 0 mV). The former effect is also mediated by AMPA/kainate receptors. The role of [Ca2+]i in the inhibition was investigated by whole cell- and nystatin-perforated patch-clamp technique. Elevation of [Ca2+]i evoked by the Ca2+ ionophores ionomycin and A23187 caused an inhibition of outward currents as well. When the elevation of [Ca2+]i is prevented, the inhibition is decreased. These results suggest that [Ca2+]i elevation may be involved in the process.