The cardiac sodium channel mRNA is expressed in the developing and adult rat and human brain

Donahue LM, Coates PW, Lee VH, Ippensen DC, Arze SE, and Poduslo SE (2000) The cardiac sodium channel mRNA is expressed in the developing and adult rat and human brain. Brain Res 887:2 335–43.

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Abstract: Expression of the rat (RH-I/SkM2) and human (hH1/SCN5A) tetrodotoxin-resistant (TTX-R), voltage-sensitive sodium channels is thought to be specific to cardiac tissue. We detected RH-I/SkM2 mRNA in newborn rat brain using both RNase protection assay analysis and in situ hybridization and in adult rat brain using RNase protection assay analysis. This expression was observed primarily in developing limbic structures of the cerebrum and diencephalon, and in the medulla of the brain stem. Using RT-PCR analysis, we detected hH1/SCN5A mRNA in both fetal and adult human brain. Interestingly, mutations in the human cardiac sodium channel are known to lead to cardiac abnormalities, which result in arrhythmias and frequently in sudden cardiac death. If these mutant channels were also expressed in limbic regions of the brain, alterations in channel function could have drastic effects on the brain's signaling ability, possibly promoting seizure activity.

Keywords: Cardiac sodium channel; RH-1/SkM2; hH1/SCN5A; Limbic; mRNA expression; Long QT3 syndrome

Context

• Identifies presence of mRNA for tetrodotoxin-resistant voltage-sensitive sodium channel, previously believed present only in heart, in fetal and adult brain. The authors highlight the implication that mutations in this channel known to cause arrhythmia could also cause epilepsy.