Vasopressin is a hormone that is primarily released when the body is low on water. Release of vasopressin causes the kidneys to conserve water by concentrating urine and decreasing urine output. However, vasopressin also has additional functions in other tissues such as the brain and blood vessels, which are not directly involved in urine production. How could it be possible for vasopressin to trigger different responses in different tissues

Vasopressin has the ability to bind to, and thereby act upon different receptors subtype, which in turn triggers different cellular responses in different tissues.

Explanation:

Vasopressin, also known as ADH, or antidiuretic hormone, is a hormone that is synthesized in hypothalamus and stored in the posterior pituatary gland. Their main function in the body is to maintain the osmolality of the blood, thus maintaining the blood volume. In addition to this, it also controls the internal temperate of the body, and also regulates circardian rythm.

Vasopressin binds to and, and act on different receptors subtypes such as:

•V1 (V1A) - located on vascular smooth muscles and also found on myometrium and platelets

•V2-found on the basolateral membrane of the collecting tubules cells of the kidney

•V3 (V1B) - mainly located in pituatary

•oxytocin-type receptors-located in the mammary glands, myometrium and endometrium of the uterus, ovary, testis, adrenals, fat cells, liver etc

Vasopressin can possibly trigger different responses in different tissues by binding to and acting on different receptor subtypes, leading to different cellular responses/effects in different tissues.

These are two major types of vasopressin receptors: V1 & V2. The V1 receptors are located on blood vessels and are responsible for the vasopressor action. The V2 receptors are in the basolateral membrane of the collecting tubule cells in the kidney, Vasopressin acts on V1, V2, V3, and oxytocin-type receptors (OTR). V1 receptors are found on vascular smooth muscle of the systemic, splanchnic, renal, and coronary circulations. They are also located on myometrium and platelets.

Vasopressin (Antidiuretic Hormone) AVP (antiviral protein; arginine vasopressin) binds to V1 receptors on vascular smooth muscle to cause vasoconstriction through the IP3 signal transduction pathway and Rho-kinase pathway, which increases arterial pressure; however, the normal physiological concentrations of AVP (antiviral protein; arginine vasopressin) are below its vasoactive range.