第 3 期 - 快速复极化
中文名称
通路描述
在第 3 期（'快速复极化'期），L 型 Ca2+ 通道关闭，而慢延迟整流（IKs）K+ 通道保持开放，随着更多 K+ 漏通道开放。这确保了净外向正电流，对应膜电位的负向变化，从而允许更多类型的 K+ 通道开放。这些主要是快速延迟整流 K+ 通道（IKr）和内向整流 K+ 电流（IK1）（Kir）。这种净外向正电流（等于细胞正电荷的损失）导致细胞复极化。主要的延迟整流 K+ 电流（IKs 和 IKr）分别由钾电压门控通道亚家族 KQT 成员 1（KCNQ1 即 Kv7.1）和钾电压门控通道亚家族 H 成员 2（KCNH2 即 HERG）介导的 K+ 外流产生（Park & Fishman 2011, Grant 2009）。特定于心房时，由钾电压门控通道亚家族 A 成员 5（KCNA5）介导的超快速激活延迟整流外向 K+ 电流（IKur）有助于复极化心房细胞（Wang et al. 1993, Feng et al. 1997）。
英文描述
Phase 3 - rapid repolarisation In phase 3 (the "rapid repolarisation" phase), the L-type Ca2+ channels close, while the slow delayed rectifier (IKs) K+ channels remain open as more K+ leak channels open. This ensures a net outward positive current, corresponding to negative change in membrane potential, thus allowing more types of K+ channels to open. These are primarily the rapid delayed rectifier K+ channels (IKr) and the inwardly rectifying K+ current, IK1 (Kir). This net outward, positive current (equal to loss of positive charge from the cell) causes the cell to repolarize. The primary delayed rectifier K+ currents (IKs and IKr) are generated by K+ efflux mediated by potassium voltage-gated channel subfamily KQT member 1 (KCNQ1 aka Kv7.1) and potassium voltage-gated channel subfamily H member 2 (KCNH2 aka HERG) channels respectively (Park & Fishman 2011, Grant 2009). Specific to the atria, an ultra-rapidly activating delayed rectifier outward K+ current (IKur) generated primarily by potassium voltage-gated channel subfamily A member 5 (KCNA5) helps to repolarize atrial cells (Wang et al. 1993, Feng et al. 1997).
所含基因
9 个基因