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应当了解,舒张期4相自动化除极过程是从舒张期最大电位起始,一直到整个窦房结细胞发生再次除极的阈电位结束。这一自动化除极过程又可分成早期与后期,早期占据了整个自动化除极过程的前2/3。换句话说,舒张期4相自动化除极的后期则从该过程的后1/3处开始,即跨膜电压到达-60m V时,使跨膜的T型Ca~(2+)通道激活开放,这使一定数量的Ca~(2+)经T型钙通道进入窦房结细胞内,使跨膜电压进一步升高,当到达-40m V时,则到达另一种L型Ca~(2+)通道激活开放的电压门控值,使L型Ca~(2+)通道激活开放,使大量的Ca~(2+)内流,并形成一次新的除极。
It should be understood that the diastolic phase 4 automatic depolarization process starts from the maximum potential of diastolic until the end of the threshold potential of the entire degeneration of the sinoatrial node cells again. This automated depolarization process can again be divided into early and late phases, occupying the first two-thirds of the entire automated depolarization process early. In other words, the late phase of the 4-phase diastolic auto-depolarization starts from the last third of the process, that is, when the transmembrane voltage reaches -60 mV, the transmembrane T-type Ca 2+ channel is activated , Which makes a certain amount of Ca2 + enter the sino-atrial node cells via T-type calcium channel and further increase the transmembrane voltage. When reaching -40 mV, another type of Ca2 + +) Channel activates an open voltage gating value, which activates the L-type Ca 2+ channel to open up a large amount of Ca 2+ influx and form a new depolarization.