sodium:proton antiporter activity involved in regulation of cardiac muscle cell membrane potential

Definition

Target type: molecularfunction

Enables the transfer of a solute or solutes from one side of a cardiac muscle cell membrane to the other according to the reaction: Na+(out) + H+(in) = Na+(in) + H+(out). This transfer contributes to the regulation of the cardiac muscle cell plasma membrane potential. [GOC:BHF, GOC:mtg_cardiac_conduct_nov11]

Sodium:proton antiporters are integral membrane proteins that catalyze the exchange of sodium ions (Na+) for protons (H+) across cell membranes. In the context of regulating cardiac muscle cell membrane potential, these antiporters play a crucial role in maintaining the balance of sodium and proton concentrations within the cell, which directly affects the electrical excitability and contractility of the heart.

The sodium:proton antiporter activity is driven by the electrochemical gradient of sodium ions. As sodium ions move down their concentration gradient from the extracellular space into the cell, they drive the movement of protons out of the cell against their concentration gradient. This process effectively removes excess protons from the intracellular environment, contributing to the regulation of intracellular pH.

The regulation of intracellular pH is essential for the proper function of cardiac muscle cells. A shift in pH can disrupt the activity of key enzymes and ion channels involved in excitation-contraction coupling, which is the process that links electrical signals to muscle contraction. Additionally, changes in pH can affect the availability of calcium ions, a critical factor in muscle contraction.

Sodium:proton antiporters are particularly important in conditions where the pH balance is disturbed, such as during myocardial ischemia, a condition characterized by reduced blood flow to the heart muscle. During ischemia, the lack of oxygen leads to a buildup of lactic acid, which lowers intracellular pH. By removing protons from the cell, the sodium:proton antiporters help to mitigate the effects of acidosis and maintain the electrical stability of the heart.

In summary, the sodium:proton antiporter activity plays a vital role in regulating cardiac muscle cell membrane potential by maintaining intracellular pH and ensuring the proper function of ion channels and other proteins involved in excitation-contraction coupling. This activity is crucial for maintaining the electrical and mechanical function of the heart, particularly in conditions where pH homeostasis is challenged.'
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Proteins (1)

Compounds (9)