Sodium-hydrogen antiporter

Sodium-Hydrogen Antiporter is a type of antiporter present in the plasma membrane of cells. It functions as a transporter protein, facilitating the exchange of sodium (Na+) and hydrogen (H+) ions across the cell membrane. This process is crucial for maintaining the pH balance and osmotic pressure within the cell.

Function

The primary function of the sodium-hydrogen antiporter is to regulate the intracellular pH and maintain the sodium balance in the cell. It does this by exchanging sodium ions for hydrogen ions. When the intracellular pH becomes too acidic, the antiporter pumps hydrogen ions out of the cell in exchange for sodium ions. This helps to neutralize the pH within the cell.

Types

There are several types of sodium-hydrogen antiporters, each with a specific function and location within the cell. These include:

• NHE1: This is the most ubiquitous type, found in nearly all mammalian cells. It is located in the plasma membrane and helps to regulate intracellular pH and cell volume.

• NHE3: This type is found primarily in the kidney and intestine, where it plays a crucial role in sodium absorption and bicarbonate secretion.

• NHE5: This type is found in the brain, where it is thought to play a role in neuronal activity.

Clinical Significance

Abnormalities in the function of sodium-hydrogen antiporters can lead to a variety of health conditions. For example, overactivity of the NHE1 antiporter has been linked to heart disease, as it can lead to an increase in intracellular sodium and calcium levels, which can cause cardiac cells to become overexcited and potentially lead to arrhythmia.

On the other hand, underactivity of the NHE3 antiporter in the kidneys can lead to a condition known as congenital sodium diarrhea, characterized by severe, life-threatening diarrhea in infants.

See Also

• Antiporter
• Transport protein
• Cell membrane
• Sodium
• Hydrogen