Role of ADH in controlling the blood pressure depends on reabsorption of water from the collecting ducts and tubules in the kidneys to the blood stream. Hypothalamus produces ADH and it is delivered to the posterior pituitary for storage and release.
When osmoreceptors in the hypothalamus detect the increment of the blood plasma concentration / blood pressure, hypothalamus signals the posterior pituitary to release the ADH into the blood. ADH constricts the arterioles in the peripheral circulation, which reduce the flow of blood to the extremities and thereby increase the blood supply into the core of the body. Not only that ADH causes the epithelial cells that lines the renal collecting tubules to move water channel proteins / aquaporins from the interior of the cells to apical surface where these proteins are inserted into the cell membrane.
This results in the increment of the water permeability of these cells and it increase the water passage from urine through the walls of the collecting tubules leading to move reabsorption of water to the blood stream. When the blood plasma concentration decreases / blood pressure increases and the level of ADH decreases the aquaporins are removed from the collecting tubule’s cell membrane and water passage from the urine into the blood decreases. So role of ADH is very important to control the blood pressure in human body.