T. Tkatch et al., Kv4.2 mRNA abundance and A-type K+ current amplitude are linearly related in basal ganglia and basal forebrain neurons, J NEUROSC, 20(2), 2000, pp. 579-588
A-type K+ currents are key determinants of repetitive activity and synaptic
integration. Although several gene families have been shown to code for A-
type channel subunits, recent studies have suggested that Kv4 family channe
ls are the principal contributors to A-type channels in the somatodendritic
membrane of mammalian brain neurons. If this hypothesis is correct, there
should be a strong correlation between Kv4 family mRNA and A-type channel p
rotein or aggregate channel currents. To test this hypothesis, quantitative
single-cell reverse transcription-PCR analysis of Kv4 family mRNA was comb
ined with voltage-clamp analysis of A-type K+ currents in acutely isolated
neurons. These studies revealed that Kv4.2 mRNA abundance was linearly rela
ted to A-type K+ current amplitude in neostriatal medium spiny neurons and
cholinergic interneurons, in globus pallidus neurons, and in basal forebrai
n cholinergic neurons. In contrast, there was not a significant correlation
between estimates of Kv4.1 or Kv4.3 mRNA abundance and A-type K+ current a
mplitudes. These results argue that Kv4.2 subunits are major constituents o
f somatodendritic A-type K+ channels in these four types of neuron. In spit
e of this common structural feature, there were significant differences in
the voltage dependence and kinetics of A-type currents in the cell types st
udied, suggesting that other determinants may create important functional d
ifferences between A-type K+ currents.