KCNIP2 and myocardial infarction: Isoform gene expression of Kcnip2, a purported master transcriptional regulator of cardiac excitability [84], was reduced in MI vs. Sham and Treatment animals, as was expression for the main depolarizing ion channel, the voltage-gated Na + channel (Nav1.5/Scn5a) (Fig. 8F).