Postnatal changes in mRNA expression of the K+ channel in rat cardiac ventricles

The reason for the postnatal changes of action potential duration in rat heart cells is still a matter of controversy. We have examined mRNA expression levels of Kv1.2, one of the K(+)-channel genes, in neonatal (1 week) and adult (8 weeks) rat cardiac ventricles. For analysis of mRNA expression, we used the reverse transcription-polymerase chain reaction method. The level of Kv1.2 mRNA expression in adult rats was significantly higher than that in neonatal rats. This result suggests that the levels of ion channel gene expression may be responsible for the postnatal changes of the action potential duration.