Question

Which of the following is an effect of aldosterone on principal cells?

1) decreased number of open Na⁺ and K⁺ channels in the basolateral membrane
2) decreased number of Na⁺/K⁺ pumps in the basolateral membrane
3) increased number of open Na⁺ and K⁺ channels in the basolateral membrane
4) increased number of open Na⁺ and K⁺ channels in the apical membrane
5) increased number of Na⁺/K⁺ pumps in the apical membrane

Answer 1

Aldosterone stimulates principal cells to increase the number of Na+/K+ pumps in the basolateral membrane, which enhances sodium reabsorption and potassium secretion.

Step-by-step explanation:

The effect of aldosterone on principal cells of the kidney is significant for the regulation of sodium and potassium balance. This steroid hormone stimulates the synthesis and activation of sodium-potassium pumps and channels to manage electrolyte and water homeostasis.

Specifically, aldosterone increases the number of sodium channels on the apical membrane and sodium-potassium pumps on the basolateral membrane of principal cells. These changes facilitate increased reabsorption of Na+ into the bloodstream, while K+ is secreted into the renal filtrate.

Therefore, the correct option, based on the effects of aldosterone, is: 5) increased number of Na+/K+ pumps in the basolateral membrane.