Na+/Cl- cotransporter (NCC)

Definition

The Na+/Cl- cotransporter, also known as the thiazide-sensitive sodium-chloride cotransporter, is a membrane protein that plays a crucial role in the regulation of sodium and chloride balance in the body. It is primarily found in the distal convoluted tubule of the nephron within the kidney.

5 Must Know Facts For Your Next Test

1. The Na+/Cl- cotransporter is responsible for the reabsorption of approximately 5-10% of the filtered sodium and chloride load in the distal convoluted tubule.
2. Inhibition of the Na+/Cl- cotransporter by thiazide diuretics leads to a decrease in sodium and chloride reabsorption, resulting in increased excretion of these ions and a reduction in blood volume and pressure.
3. Genetic mutations in the gene encoding the Na+/Cl- cotransporter can lead to Gitelman syndrome, a rare inherited disorder characterized by low blood pressure, low potassium levels, and other electrolyte imbalances.
4. The activity of the Na+/Cl- cotransporter is regulated by various hormones, such as aldosterone, angiotensin II, and insulin, which modulate its expression and function.
5. Disruption of the Na+/Cl- cotransporter's function can contribute to the development of hypertension, a major risk factor for cardiovascular diseases.

Review Questions

• Explain the role of the Na+/Cl- cotransporter in the regulation of sodium and chloride balance in the body.
  • The Na+/Cl- cotransporter, located in the distal convoluted tubule of the nephron, plays a crucial role in the reabsorption of sodium and chloride from the filtered fluid. It is responsible for the reabsorption of approximately 5-10% of the filtered sodium and chloride load, helping to maintain fluid and electrolyte balance in the body. The activity of the Na+/Cl- cotransporter is regulated by various hormones, such as aldosterone and angiotensin II, which modulate its expression and function.
• Describe how the inhibition of the Na+/Cl- cotransporter by thiazide diuretics can be used as a therapeutic approach for the treatment of hypertension and edema.
  • Thiazide diuretics, a class of medications, work by inhibiting the Na+/Cl- cotransporter in the distal convoluted tubule. This inhibition leads to a decrease in the reabsorption of sodium and chloride, resulting in increased excretion of these ions and a reduction in blood volume and pressure. By targeting the Na+/Cl- cotransporter, thiazide diuretics effectively lower blood pressure and can be used as a therapeutic approach for the management of hypertension and edema. The inhibition of the Na+/Cl- cotransporter also plays a role in the treatment of Gitelman syndrome, a rare genetic disorder characterized by electrolyte imbalances.
• Analyze the potential consequences of genetic mutations in the gene encoding the Na+/Cl- cotransporter and their impact on the body's fluid and electrolyte homeostasis.
  • Genetic mutations in the gene encoding the Na+/Cl- cotransporter can lead to the development of Gitelman syndrome, a rare inherited disorder. Individuals with Gitelman syndrome experience disruptions in the normal function of the Na+/Cl- cotransporter, resulting in decreased reabsorption of sodium and chloride in the distal convoluted tubule. This imbalance can lead to a cascade of effects, including low blood pressure, low potassium levels, and other electrolyte disturbances. The impaired function of the Na+/Cl- cotransporter in Gitelman syndrome highlights the critical role this transporter plays in maintaining fluid and electrolyte homeostasis in the body, and the potential consequences of genetic variations that disrupt its normal operation.

Related terms

Nephron: The functional unit of the kidney responsible for the filtration, reabsorption, and secretion of substances to maintain fluid and electrolyte balance in the body.

Distal Convoluted Tubule: The segment of the nephron located after the loop of Henle, where the Na+/Cl- cotransporter is primarily expressed and plays a key role in sodium and chloride reabsorption.

Thiazide Diuretics: A class of medications that inhibit the Na+/Cl- cotransporter, leading to increased excretion of sodium, chloride, and water, making them effective in the treatment of hypertension and edema.