Abstract：
In this study, we wanted to verify whether the effect of insulin on calcium homeostasis depends on the heart\'s development stage. Using a quantitative 3D confocal microscopy, we tested the effect of a high insulin concentration (100 µU) in freshly cultured ventricular cardiomyocytes from newborn and adult rats. Our results showed that the cytosolic basal level of calcium was higher in newborn cardiomyocytes with no change in the nuclear basal calcium level compared with the adult cardiomyocytes; in addition, insulin induced a slow increase of cytosolic and nuclear calcium in newborn ventricular cardiomyocytes, followed by two phases. However, the first phase of slow cytosolic and nuclear calcium increase was absent in adult rat ventricular cardiomyocytes. Furthermore, the time to the onset of increase of cytosolic and nuclear calcium was longer in newborn cardiomyocytes compared with adults. Moreover, the time to peak of the calcium transient was shorter in newborns than in adult cardiomyocytes. These results demonstrate that insulin differently regulates calcium homeostasis in newborns than in adult cardiomyocytes. Thus, newborn rat cardiomyocytes, commonly used in research as a model for adult cardiomyocytes, should be used with caution when dealing with insulin in normal and disease conditions.
摘要：
在这项研究中,我们想验证胰岛素对钙稳态的影响是否取决于心脏的发育阶段。使用定量3D共聚焦显微镜，我们测试了高胰岛素浓度(100µU)对新生和成年大鼠心室心肌细胞的影响.我们的结果表明，与成年心肌细胞相比，新生心肌细胞的胞浆基础钙水平较高，而细胞核基础钙水平没有变化；此外，胰岛素诱导新生心室心肌细胞胞浆和细胞核钙的缓慢增加，其次是两个阶段。然而,成年大鼠心室心肌细胞中不存在第一阶段缓慢的胞浆和核钙增加。此外，与成人相比,新生心肌细胞胞浆和细胞核钙开始升高的时间更长.此外，新生儿钙瞬变达到峰值的时间比成人心肌细胞短。这些结果表明，与成年心肌细胞相比，胰岛素对新生儿钙稳态的调节方式不同。因此，新生大鼠心肌细胞，通常在研究中用作成人心肌细胞的模型，在正常和疾病情况下处理胰岛素时应谨慎使用。
