KCNJ3 and atrial fibrillation: Also, miR30d is significantly upregulated in cardiomyocytes from AF patients, whereas the mRNA and protein levels of KCNJ3/Kir3.1, postulated target of miR-30d, are markedly reduced, concomitant with a reduction of the acetylcholine-sensitive inward-rectifier K+ current (IK.ACh) [141].