Where does aldosterone specifically regulate sodium reabsorption in the nephron?

Aldosterone specifically regulates sodium reabsorption primarily in the distal convoluted tubule and the collecting duct of the nephron, with the distal convoluted tubule being one of the key sites for its action. This hormone is secreted by the adrenal cortex in response to signals indicating low blood volume, low blood pressure, or low sodium levels.

In the distal convoluted tubule, aldosterone acts on mineralocorticoid receptors in the principal cells, enhancing the expression of sodium channels (ENaC) and sodium-potassium ATPase pumps. This increases sodium reabsorption from the filtrate back into the bloodstream, which ultimately contributes to an increase in blood volume and pressure. While the collecting duct also plays a significant role in sodium reabsorption influenced by aldosterone, the question specifically highlights the distal convoluted tubule as its primary action site.

Through this mechanism, aldosterone helps maintain electrolyte balance and influences fluid volume, making it a critical component in the regulation of cardiovascular and renal health.