Fig. 5. Expression of HCN channel transcripts in wild-type and HCN2 knockout brain. (A) Autoradiograms of brain sections hybridized in situ with HCN1, HCN3 and HCN4 probes under control conditions. (B) HCN subunit expression under control conditions. HCN mRNA levels were quantified by analysis of phosphorimaged sections (n = 6–8 for each genotype and HCN isoform). PSL, photo-stimulated luminescence units; Cx, cortex; Th, thalamus; CA1–3, CA1–3 regions of the hippocampus. (C) HCN subunit expression after chronic application of ethosuximide over 4 weeks.