Institut für Pharmakologie und Toxikologie, Medizinische Fakultät, Martin-Luther-Universität Halle-Wittenberg, 06112 Halle (Saale), Germany.
J Mol Cell Cardiol. 2011 Nov;51(5):682-8. doi: 10.1016/j.yjmcc.2011.08.007. Epub 2011 Aug 17.
In the neonatal mammalian heart, the role of ryanodine receptor (=Ca(2+) release channel)-mediated sarcoplasmic reticulum (SR) Ca(2+) release for excitation-contraction coupling is still a matter of debate. Using an adenoviral system, we overexpressed separately the junctional SR proteins triadin, junctin, and calsequestrin, which are probably involved in regulation of ryanodine receptor function. Infection of neonatal rat cardiac myocytes with triadin, junctin, or calsequestrin viruses, controlled by green fluorescent protein expression, resulted in an increased protein level of the corresponding transgenes. Measurement of Ca(2+) transients of infected cardiac myocytes revealed unchanged peak amplitudes under basal conditions but with overexpression of calsequestrin and triadin caffeine-releasable SR Ca(2+) content was increased. Our results demonstrate that an increased expression of triadin or calsequestrin is associated with an increased SR Ca(2+) storage but unchanged Ca(2+) signaling in neonatal rat cardiac myocytes. This is consistent with an ancillary role of the sarcoplasmic reticulum in excitation-contraction coupling in the developing mammalian heart.
在新生哺乳动物的心脏中，兰尼碱受体（=Ca(2+)释放通道）介导的肌浆网（SR）Ca(2+)释放对兴奋-收缩偶联的作用仍存在争议。我们使用腺病毒系统分别过表达了可能参与调节兰尼碱受体功能的连接 SR 蛋白三联素、连接蛋白和肌浆网钙结合蛋白。受绿色荧光蛋白表达控制的感染新生大鼠心肌细胞的三联素、连接蛋白或肌浆网钙结合蛋白病毒导致相应转基因的蛋白水平增加。对感染心肌细胞的 Ca(2+)瞬变的测量表明，基础条件下峰值幅度不变，但肌浆网钙结合蛋白和三联素过表达时，咖啡因可释放的 SR Ca(2+)含量增加。我们的结果表明，三联素或肌浆网钙结合蛋白的表达增加与 SR Ca(2+)储存增加但新生大鼠心肌细胞的 Ca(2+)信号不变有关。这与在发育中的哺乳动物心脏中，肌浆网在兴奋-收缩偶联中具有辅助作用的观点一致。
