regulation of cardiac muscle cell membrane potential

Definition

Target type: biologicalprocess

Any process that modulates the establishment or extent of a membrane potential in a cardiac muscle cell (a cardiomyocyte). A membrane potential is the electric potential existing across any membrane arising from charges in the membrane itself and from the charges present in the media on either side of the membrane. [GOC:BHF, GOC:mtg_cardiac_conduct_nov11]

The regulation of cardiac muscle cell membrane potential is a complex process that involves the coordinated activity of various ion channels and transporters. The resting membrane potential of a cardiac muscle cell is typically around -90 mV, which is maintained by the sodium-potassium pump, a transmembrane protein that actively transports sodium ions out of the cell and potassium ions into the cell. This creates a concentration gradient that favors the movement of potassium ions out of the cell and sodium ions into the cell.

The opening of voltage-gated sodium channels during the depolarization phase of an action potential allows sodium ions to flow into the cell, rapidly depolarizing the membrane potential. This depolarization wave then spreads throughout the cell, triggering the opening of voltage-gated calcium channels. These channels are responsible for the plateau phase of the cardiac action potential, which is characterized by a sustained depolarization. The prolonged duration of the plateau phase is essential for the contraction of cardiac muscle cells.

The influx of calcium ions through the voltage-gated calcium channels also activates the ryanodine receptors, which are calcium channels located on the sarcoplasmic reticulum. The opening of these channels releases a large amount of calcium ions into the cytoplasm, further increasing the intracellular calcium concentration. This rise in intracellular calcium concentration triggers the contraction of the cardiac muscle cell.

As the action potential progresses, the voltage-gated sodium channels inactivate and the potassium channels open. The efflux of potassium ions out of the cell repolarizes the membrane potential, returning it to its resting state.

The regulation of cardiac muscle cell membrane potential is also influenced by the activity of other ion channels and transporters, such as the sodium-calcium exchanger and the potassium-chloride cotransporter. The sodium-calcium exchanger removes calcium ions from the cell by exchanging them for sodium ions. The potassium-chloride cotransporter regulates the intracellular chloride concentration, which can influence the membrane potential.

The regulation of cardiac muscle cell membrane potential is essential for normal heart function. Any disruption in the function of the ion channels or transporters involved in this process can lead to cardiac arrhythmias, which can be life-threatening. Therefore, understanding the mechanisms underlying the regulation of cardiac muscle cell membrane potential is crucial for the diagnosis and treatment of heart disease.'
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Proteins (3)

Compounds (15)