Studies on the regulation of myocardial SR calcium release channel under in situ environment

将具有针对线粒体和内质网的靶向序列的黄驼cDNA包装到改进的腺病毒载体中，并引入原代培养的心肌细胞和肝细胞中。通过与TMRE等的荧光比较，证实了探针对细胞器的靶向。用快速扫描共聚焦显微镜检查心房和心室之间的兴奋-收缩机制的差异。CICR机制的传播参与心房肌细胞的正常EC偶联，但不参与心室肌细胞。这种差异是由于心房肌细胞中T-小管的缺乏，而不是单个释放单位性质的差异，这可能解释了心房和心室之间的一些药理学差异。我们研究了三种膜蛋白在触发钙离子从兰尼碱受体通道释放中的作用。在心房和心室心肌细胞中，L型而不是T型钙通道参与触发钙释放。钠-钙交换器，当被α肾上腺素能刺激等因素激活时，发现通过减少钙负荷间接减少肌浆网的钙释放。

cDNAs for Yellow Cameleons with targeting sequences towards the mitochondria and endoplasmic reticulum were packaged into an inproved adenoviral vector and were introduced to primary cultured cardiomyocytes and hepatocytes. The targetting of the probes to organella were confirmed by comparing the fluorescence with those of TMRE etc. Difference in excitation-contraction mechanisms between the atria and ventricle were examined with rapid scanning confocal microscopy. A propagation of CICR mechanisms was involved in normal EC coupling in atrial myocytes but not in ventricular myocytes. This difference was due to the absence of T-tubules in atrial myocytes rather than difference in the properties of individual release unitsand might explain some of the pharmacological difference between the atria and ventricle. We examined the role of three membrane proteins in triggering calcium release from the ryanodine receptor channel. In both atrial and ventricular cardiomyocytes, L-type, but not T-type calcium channels were involved in triggering calcium release. The sodium-calcium exchanger, when activated by factors such as alpha adrenergic stimulation, was found to reduce calcium release from the sarcoplasmic reticulum indirectly through decrease in calcium load.