The entire event last between 250 and 300 ms.

Figure 1.行为ion potential of contractile cardiac muscle cells.

1.去极化

Rapid Na⁺influx through fast voltage-gated Na⁺channels, beginning the positive-feedback mechanism of depolarization. This rapid increase the membrane potential to +30mV, at which point the sodium (Na⁺)通道关闭。

2. Plateau phase

Ca²⁺influx through slow Ca²⁺channels. This keeps the cell depolarized because most K⁺channels are closed. The plateau lasts approximately 175 ms.

3. Repolarization

Ca²⁺channel close and K+ to exit the cell.

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• 行为ion potential of conducting cells