The
antidiuretic hormone arginine vasopressin (AVP) receptors are
G protein-coupled and have been divided into at least three types: V1a (vascular/hepatic) and V1b (anterior pituitary) receptors, which act through
phosphatidylinositol hydrolysis to mobilize intracellular Ca2+; and V2 (kidney) receptor, which is coupled to
adenylate cyclase. Recently V1a and
V2 receptor cDNAs were cloned. These cDNAs encode
proteins with seven putative transmembrane domains and a similar structure to
rhodopsin and other
G protein-coupled receptors. Micro-localization of
mRNA coding for V1a and
V2 receptors was carried out in the rat kidney using a reverse transcription and polymerase chain reaction. Large signals for V1a receptor PCR product were detected in glomerulus, cortical collecting duct (CCD), outer medullary collecting duct (OMCD), inner medullary collecting duct (IMCD), and arcuate artery. Large signals for
V2 receptor PCR product were detected in CCD, OMCD, and IMCD. 72-hour
dehydration caused decrease of
V2 receptor mRNA, but no change in V1a receptor
mRNA in rat IMCD. These data show that
mRNA coding for the two AVP receptor subtypes are distributed differently along the nephron and renal vascular system, and that these mRNAs are regulated differently in response to the dehydrated state. Recently, two reports of a mutation in the
vasopressin V2 receptor gene in a kindred with X-rinked
nephrogenic diabetes insipidus are published. These studies demonstrated that point mutation of
V2 receptor gene causes the
nephrogenic diabetes insipidus. Understanding the nature of defective
diabetes insipidus may ultimately lead to improved
therapy.