The homeobox-containing gene Csx/Nkx2.5 codes several cardiac transcription factors and plays a critical role in early cardiogenesis. We investigated the effect of Csx/Nkx2.5 on the expression of cardiac ion channels using P19-derived cardiomyocytes. P19CL6 cells and P19CL6 cells with Csx/Nkx2.5 overexpression (P19CL6-Csx cells) were induced to differentiate into cardiomyocytes by treatment with dimethyl sulfoxide. Action potentials and membrane currents were measured by whole cell patch clamp at different differentiation stage: the early stage (1–5 days after beating had begun) and the late stage (10–15 days after beating). Expression of Csx/Nkx2.5 mRNA was increased as the differentiation stages advanced in both P19CL6 and P19CL6-Csx cells. In action potential configuration, maximal diastolic potentials in P19CL6-Csx cells exhibited more hyperpolarized potential (‒ 64.2 mV) than those in P19CL6 cells (‒ 54.8 mV, p  < 0.01) in the early stage. In P19CL6 cells, among 6 different voltage-gated and ligand-operated K⁺ channels expressed during the early stage, the transient-outward K⁺ channel was most predominant. By overexpression of Csx/Nkx2.5, developmental decrease in the transient-outward K⁺ channel was suppressed. Homeobox-containing gene Csx/Nkx2.5 modifies the amount of distinct ionic channels, during differentiation periods, predominantly changing the expression of the transient-outward K⁺ channel.

中文翻译：

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心脏特异性转录因子Csx / Nkx2.5调节多能性P19细胞来源的心肌细胞中的瞬时向外K ⁺通道表达

包含同源盒的基因Csx / Nkx2.5编码几种心脏转录因子，并在早期心脏发生中起关键作用。我们调查了Csx / Nkx2.5对使用P19衍生的心肌细胞表达心脏离子通道的影响。通过用二甲基亚砜处理，诱导Csx / Nkx2.5过表达的P19CL6细胞和P19CL6细胞（P19CL6-Csx细胞）分化为心肌细胞。通过全细胞膜片钳在不同的分化阶段测量动作电位和膜电流：早期（开始搏动后1–5天）和晚期（搏动后10–15天）。随着P19CL6和P19CL6-Csx细胞分化阶段的进展，Csx / Nkx2.5 mRNA的表达增加。在实际操作中， p  <0.01）。在P19CL6细胞中，在早期表达的6个不同的电压门控和配体操作的K ⁺通道中，瞬时向外K ⁺通道最为主要。通过Csx / Nkx2.5的过表达，抑制了瞬时向外K ⁺通道的发育下降。包含同源盒的基因Csx / Nkx2.5在分化期修改了不同离子通道的数量，主要改变了瞬时向外K ⁺通道的表达。