LVA Ca2+ current in isolated associative neurons from the laterodorsal thalamic nucleus of 14- to 17-day-old rats was dissected into two, 'fast' and 'slow', components based on the difference in the kinetics of inactivation. The selectivity of the channel responsible for the fast LVA current for Ca2+, Sr2+ and Ba2+ (I(Ca):I(Sr):I(Ba) = 1.0:1.23:0.94) as well as the shifts of the I-V produced by these ions were found to be almost identical to those observed for LVA channels in other preparations. The channel responsible for the slow LVA current showed selectivity more characteristic of HVA Ca2+ channels (I(Ca):I(Sr):I(Ba) = 1.0:2.5:3.4), although the ability of Ca2+, Sr2+ and Ba2+ to shift its voltage dependence remained the same as for the fast channel.