钙离子作为第二信使,与其细胞内的受体(钙调蛋白)构成一类新的细胞内信息传递系统,参与多种细胞功能,为解释药物作用机制开辟了新的途径。在肌肉兴奋-收缩耦联中,钙离子是一个关键物质。平滑肌与骨骼肌及心肌具有基本相似的肌肉收缩机制,但它们在结构和机能上又存在着明显的区别。例如骨 As a second messenger, calcium ion constitutes a new type of intracellular information delivery system with its intracellular receptor (calmodulin) and participates in many cellular functions, opening up new avenues for explaining the mechanism of drug action. In the muscle excitatory-contractive coupling, calcium is a key substance. Smooth muscle and skeletal muscle and cardiac muscle have a similar mechanism of muscle contraction, but their structure and function there is a clear distinction. For example, bone