Arginine vasopressin or antidiuretic hormone has got name “vasopressin”
due to its vasoconstrictor properties. Vasopressin is a posterior pituitary hormone
which is essential for the cardiovascular homeostasis. In normal physiological
conditions, it helps in regulation of plasma osmolality and volume via its action on the
kidney. Other important actions of vasopressin include regulation of vascular smooth
muscle tone, control of circadian rhythm, thermoregulation, and adrenocorticotropic
hormone release (ACTH).
In recent years, vasopressin has emerged as an important therapeutic option in the
treatment of various shock states. Vasopressin has increasingly been used in both
pediatric and adult critical care units for the management of central diabetes insipidus,
bleeding abnormalities, oesophageal variceal haemorrhage, asystolic cardiac arrest, and
various shock states e.g. shock due to ventricular fibrillation, hypovolaemia, sepsis and
cardiopulmonary bypass.
Ongoing researches helped in increasing understanding of the endocrine response to
shock and importance of vasopressin in their management. Prolonged vasodilatory
shock is characterised by relative deficiency of endogenous vasopressin and marked
vasopressor effects of the exogenously administered hormone. Sepsis and post
cardiopulmonary bypass conditions are the most common causes of vasodilatory shock;
however, vasodilation can be a common final pathway of any type of shock. Unlike
other vasoconstrictors, vasopressin also exerts some vasodilatory properties which can
be due to its action on various receptors, namely V1 vascular, V2 renal, V3 pituitary
and oxytocin receptors, and the P2 purinergic receptors producing variable and
seemingly contradictory responses.
To better understand the variable responses on the vascular system, which vasopressin
exerts, it is prudent to acquire the knowledge of the physiology and action of the
different vasopressin receptors. In this chapter, vascular actions of vasopressin along
with distribution of the classic vasopressin receptors and signalling pathways will be
explored.
Keywords: Arginine-vasopressin, Oxytocin receptors, Terlipressin, Vasopressin,
Vasopressin receptors.
