Furthermore, it raises the expression of AQP5mRNA in salivary gland and submandibular gland tissue to some extent and this and additional medications may be able to increase the amount of AQP5, which can spur moisture transport rate, increase a cell's cytoplasmic volume, promote gland secretion, and therefore improve the symptoms of xerostomia [27, 28]. Here, AQP5 is linked to xerostomia.