Midnolin (Midn) is a developmentally regulated nucleolar protein that was originally identified in the mesencephalon of developing mouse embryos. Additionally, Midn expression was detected in various adult tissues and was associated with glucokinase activity in pancreatic beta cells and with the regulation of folliculogenesis in ovaries. In this study, our aim was to analyze the expression and function of the Midn gene in cardiomyocyte cells. We constructed a primary neonatal mouse cardiomyocyte cell culture and analyzed the expression of possible Midn-associated genes after short interfering RNA (siRNA)-mediated gene silencing for Midn. After 24 h of silencing, we observed that the expression level of Bat3 was significantly increased (1.69-fold, P = 0.04). As a result, we have detected a suggestive gene that might act in the common cellular pathways with Midn in cardiomyocyte cells.