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)
| Protein | Definition | Taxonomy |
|---|---|---|
| Sodium/hydrogen exchanger 1 | A sodium/hydrogen exchanger 1 that is encoded in the genome of human. [PRO:DNx, UniProtKB:P19634] | Homo sapiens (human) |
Compounds (9)
| Compound | Definition | Classes | Roles |
|---|---|---|---|
| ethylisopropylamiloride | ethylisopropylamiloride : A member of the class of pyrazines that is amiloride in which the amino substitutent of the pyrazine ring that is adjacent to the chloro substituent has been substituted by an ethyl group and by an isopropyl group. ethylisopropylamiloride: structure in first source | aromatic amine; guanidines; monocarboxylic acid amide; organochlorine compound; pyrazines; tertiary amino compound | anti-arrhythmia drug; neuroprotective agent; sodium channel blocker |
| benzotriazole | benzotriazole : The simplest member of the class of benzotriazoles that consists of a benzene nucleus fused to a 1H-1,2,3-triazole ring. benzotriazole: inhibitor of atmospheric metal corrosion; also component of motion picture film & Neva brake fluid | benzotriazoles | environmental contaminant; xenobiotic |
| amiloride | amiloride : A member of the class of pyrazines resulting from the formal monoacylation of guanidine with the carboxy group of 3,5-diamino-6-chloropyrazine-2-carboxylic acid. Amiloride: A pyrazine compound inhibiting SODIUM reabsorption through SODIUM CHANNELS in renal EPITHELIAL CELLS. This inhibition creates a negative potential in the luminal membranes of principal cells, located in the distal convoluted tubule and collecting duct. Negative potential reduces secretion of potassium and hydrogen ions. Amiloride is used in conjunction with DIURETICS to spare POTASSIUM loss. (From Gilman et al., Goodman and Gilman's The Pharmacological Basis of Therapeutics, 9th ed, p705) | aromatic amine; guanidines; organochlorine compound; pyrazines | diuretic; sodium channel blocker |
| amiloride hydrochloride | amiloride hydrochloride dihydrate : A hydrate that is the dihydrate of amiloride hydrochloride. | hydrate | diuretic; sodium channel blocker |
| cariporide | cariporide: a selective sodium-hydrogen exchange subtype 1 inhibitor; structure in first source | ||
| eniporide | eniporide: inhibits NHE-1 isoform; structure in first source | ||
| zoniporide | zoniporide: inhibits sodium-hydrogen exchanger isoform-1 (NHE-1) | ||
| sabiporide | sabiporide: a NHE-1 inhibitor and a cardioprotective agent; structure in first source | ||
| (5-(2-methoxy-5-chloro-5-phenyl)furan-2-ylcarbonyl)guanidine | (5-(2-methoxy-5-chloro-5-phenyl)furan-2-ylcarbonyl)guanidine: KR-32570 possesses potent cardioprotective effects in perfused rat hearts, and its effects may be mediated by inhibition of NHE-1, preservation of high-energy phosphates, and inhibition of lipid peroxidation |