心脏的起搏受控于一类存在于心脏窦房结被称作If 的离子通道 ,该通道是被细胞膜的超极化所激活 .新近 ,一类被命名为超极化激活及环化核苷酸调控的阳离子 (HCN)通道被克隆 .该家族至少有4个成员 ,即HCN1～HCN4 .其中 2个HCN2和HCN4在心脏有丰富表达 .用异体表达系统表达克隆的HCN2和HCN4通道蛋白 ,其通道特性类似心脏的天然If 通道 .本综述讨论了HCN通道之间的分子结构差异 ,功能性表达特点以及与它们功能特性有关的分子结构 Cardiac pacing is controlled by a class of ion channels known as If located in the cardiac sinoatrial node that is activated by hyperpolarization of the cell membrane.Newly, a class named hyperpolarization-activated and cyclized nuclei (HCN) channel was cloned.This family has at least 4 members, HCN1 ~ HCN4, of which 2 HCN2 and HCN4 are abundantly expressed in the heart.The expression of cloned HCN2 and HCN4 channel proteins is expressed by using the allogeneic expression system, Its chan- nel properties resemble the natural If channel of the heart.This review discusses the molecular structural differences between HCN channels, their functional expression profile and the molecular structure associated with their functional properties