Comprehensive Analysis of Structure and Contractile Performance of Myocardium during Development

离体成人心肌细胞呈棒状，横条纹清晰。然而，分离的新生大鼠心肌细胞或胚胎干细胞诱导的心肌细胞呈星形，没有明显的横向条纹。为了分析心肌细胞肌丝结构的发展，我们使用Spring-8进行了x射线衍射分析。我们发现新生大鼠心脏肌丝晶格排列不良。2周发育期间平均丝间晶格间距差异不大，出生时丝间晶格间距偏差较大，随发育而减小。我们还考虑了发育不良的肌丝如何产生足够的压力来灌注全身。根据拉普拉斯定律，小心室需要小的张力来产生足够的压力。然后，排列良好的肌丝即使在发育良好的心室也能提供足够的压力。

Isolated adult cardiomyocytes show rod shape with clear transverse striation pattern. However, isolated neonatal rat cardiomyocytes or induced cardiomyocytes of embryonic stem cells show star shape without clear transverse striation pattern. To analyze the development of structure of myofilament of cardiomyocytes, we performed x-ray diffraction analysis using Spring-8. We found that myofilament of neonatal rat heart had poor aligned myofilament lattice. the averaged inter filament lattice spacing was not so different during development over two weeks, deviation of interfilament lattice spacing was quite large at birth and decreased with development. We also considered how the poorly developed myofilament creates enough pressure to perfuse whole body. According to Laplace's law, small ventriclele requires small tension to create the enough pressure. Then, the well aligned myofilament can provide enough pressure even in the well developed ventricle.