ASSOCIATION OF α-SCA, α-SMA AND DESMIN WITH THE MYOCARDIAL MATURATION OF THE EMBRYONIC MOUSE HEART / 解剖学报

ABSTRACT

Objective To investigate the spatiotemporal expression patterns and the relationship of α-sarcomeric actin(α-SCA) ,α-smooth muscle actin(α-SMA) and intermediate filament protein desmin with the maturation of the prenatal and the neonatal mouse hearts. Methods Serial sections of the embryo mouse and the neonatal mouse hearts were immunostained with antibodies against α-SCA, α-SMA and desmin. Results Ventricle and outflow tract of embryonic day(ED) 9 heart showed stronger expression of α-SCA and α-SMA, but desmin expression was lower. In the atrium, the expressions of α-SCA and α-SMA were restricted to the dorsal and ventral walls. In the sinus venosus, only a few weakly stained α-SCA positive cells were detected. No desmin expression was found in the atrium and sinus venosus. The expressions of α-SCA, α-SMA and desmin were increased to their highest level at ED 12. The higher expression of α-SCA remained to the postnatal stages. After ED 12, the expressions of α-SMA and desmin gradually decreased in different parts of the heart, but their expressions in the right ventricle persisted longer. After birth,desmin expression was mainly concentrated in the Z lines of I bands and intercalated disks. Conclusion The presence of spatiotemporal differences in the expression of α-SMA and desmin reveals regional differences in cardiomyocyte maturation in various parts of the embryonic mouse heart. The right ventricle shows a relatively slow pace of maturation. The α-SMA may contribute to a peristaltoid contraction pattern of the embryonic myocardium with a slow shortening speed, and a relatively higher level of desmin is required for the maturation of the sarcomere.