How does aldosterone indirectly affect blood pressure?

Aldosterone plays a crucial role in the regulation of blood pressure primarily through its effect on sodium reabsorption in the kidneys. When aldosterone is released (for instance, during times of low blood pressure or low sodium levels), it acts on the distal convoluted tubules and collecting ducts within the nephron of the kidney, promoting the reabsorption of sodium back into the bloodstream.

As sodium is reabsorbed, it increases the osmotic pressure in the blood, leading to an associated increase in water retention due to osmosis. When more sodium and water are present in the bloodstream, the overall blood volume increases. This increase in blood volume results in a rise in blood pressure, as more fluid in the vascular system creates more pressure against the walls of the blood vessels.

This connection highlights how aldosterone indirectly affects blood pressure: by increasing the reabsorption of sodium, it leads to an increase in blood volume and consequently raises blood pressure.