Action potential in the contractile cardiac muscle fibers has a unique shape with a long plateau. What ion channels are responsible for the plateau phase of cardiac action potential?

Question

Quizplus · Accepted Answer

The plateau phase of cardiac action potential is due to the opening of L type voltage gated Ca2+ channels, also known as Ca²⁺ channels, which allow for a slow and sustained influx of calcium ions into the cell. This gradual influx of calcium ions maintains the depolarization phase for a longer period of time, leading to the unique shape of the cardiac action potential in contractile muscle fibers. T type voltage gated Ca2+ channels (choice B) are involved in the initiation of the action potential in pacemaker cells, but not in the plateau phase of cardiac action potential. Fast voltage gated K+ channels (choice C) and F type Na+ channels (choice D) also do not contribute to the plateau phase.

Action Potential in the Contractile Cardiac Muscle Fibers Has a Unique