Calcium regulation in cardiac cells

Calcium is a common signaling mechanism, as once it enters the cytoplasm it exerts allosteric regulatory affects on many enzymes and proteins. Calcium can act in signal transduction after influx resulting from activation of ion channels or as a second messenger caused by indirect signal transduction pathways such as G protein-coupled receptors. Movement of calcium ions from the extracellular compartment to the intracellular compartment alters membrane depolarisation. This is seen in the heart, during the plateau phase of ventricular contraction. In this example, calcium acts to maintain depolarisation of the heart. Source: [[wikipedia:Calcium_signaling|Wikipedia]]

钙离子作为一种普遍的信号传导机制，一旦进入细胞质，便对众多酶和蛋白质施加别构调节效应。钙离子能够在离子通道激活后引起的内流所导致的信号传导过程中发挥作用，亦或作为由G蛋白偶联受体等间接信号传导途径引起的第二信使。钙离子从细胞外区室向细胞内区室的迁移，改变了膜的去极化状态。这一现象在心脏的舒张末期尤为显著，此时钙离子发挥着维持心肌去极化的作用。来源：[维基百科：钙信号传导](https://zh.wikipedia.org/wiki/钙信号传导)