Zebrafish sodium channel β1-4 subunit genes and novel splice variants are differentially expressed in excitable tissues. Total RNA was isolated from wild-type adult zebrafish tissues. RT-PCR with gene and splice variant-specific primers was used to detect expression (see Table 5 for primer sequences and amplicon details). Atr = atrium, Ven = ventricle, Skm = skeletal muscle, Brn = Brain, Eye = eye/optic nerve, Liv = liver, Gil = gill. + = enzyme added to reverse transcription step, - = no reverse transcriptase enzyme (negative control). Zebrafish β-actin was amplified from each template as a positive control.