Aquaporins

Aquaporins are water transport channel proteins to aid reabsorption. They are found most abundantly in regions involved in transporting particularly high rates of water, for example in the epithelial cells of the collecting duct at the end of a nephron in the kidney.

The fusion of more aquaporins to the cell surface membrane is stimulated by the reception of ADH (anti-diuretic hormone), which is secreted in times of water shortage by the posterior pituitary gland, decreases water loss through urine.