What is the mechanism of action of aldosterone?

Aldosterone is a steroid hormone produced by the adrenal cortex, and its primary function is to regulate electrolyte balance in the body, especially sodium and potassium levels. The primary mechanism of action of aldosterone is that it stimulates sodium resorption in the distal renal tubules and collecting ducts of the nephron. It binds to mineralocorticoid receptors located in the principal cells of these nephrons, leading to the activation of transcription of various genes that promote the reabsorption of sodium from the tubular fluid back into the bloodstream.

This action results in increased sodium retention, which in turn leads to an increase in water retention via osmosis, contributing to an increase in blood volume and blood pressure. Additionally, as sodium is reabsorbed, potassium is typically exchanged and subsequently excreted, which can lead to a decrease in serum potassium levels. This exchange is a critical aspect of aldosterone's role and underscores its importance in maintaining electrolyte equilibrium and fluid balance in the body.