Arg8-Vasopressin: ProductsArginine8-Vasopressin (Arg8-Vasopressin) is a 9-amino acid peptide structurally related to oxytocin. It is synthesized in the hypothalamic supraoptic and paraventricular nuclei, and is stored in the posterior pituitary for release. Arg8-Vasopressin has a powerful antidiuretic action and is also known as antidiuretic hormone (ADH). It acts on the collecting tubule of the kidney increasing permeability to water and urea. It also has neurotransmitter and peripheral humoral functions.