Aldosterone acts on the distal tubules where it increases absorption of sodium. Aldosterone is regulating the sodium balance of the body. Aldosterone increases the number of active NA+/ K+pumps so that an increasing number of these work simultaneously and of the movement of sodium into the blood capillaries increases. This also means that aldosterone increases the excretion of potassium in the filtrate (uptake of sodium occurs while potassium is secreted). Since sodium uptake increases, an additional effect of aldosterone is that water follows – and thus the reabsorption of water uptake also increases.