Vasopressin regulation of the renal UT-A3 urea transporter

• Published in: American journal of physiology. Renal physiology Vol. 296; no. 3; p. F642
• Main Authors: Stewart, G S, Thistlethwaite, A, Lees, H, Cooper, G J, Smith, Craig
• Format: Journal Article
• Language: English
• Published: United States 01-03-2009
• Subjects: Animals; Casein Kinase II - metabolism; Cell Line; Dogs; Kidney - metabolism; Membrane Transport Proteins - metabolism; Urea - metabolism; Urea Transporters; Vasopressins - metabolism
• ISSN: 1931-857X
• DOI: 10.1152/ajprenal.90660.2008

Facilitative urea transporters in the mammalian kidney play a vital role in the urinary concentrating mechanism. The urea transporters located in the renal inner medullary collecting duct, namely UT-A1 and UT-A3, are acutely regulated by the antidiuretic hormone vasopressin. In this study, we investigated the vasopressin regulation of the basolateral urea transporter UT-A3 using an MDCK-mUT-A3 cell line. Within 10 min, vasopressin stimulates urea flux through UT-A3 transporters already present at the plasma membrane, via a PKA-dependent process. Within 1 h, vasopressin significantly increases UT-A3 localization at the basolateral membrane, causing a further increase in urea transport. While the basic trafficking of UT-A3 to basolateral membranes involves both protein kinase C and calmodulin, its regulation by vasopressin specifically occurs through a casein kinase II-dependent pathway. In conclusion, this study details the effects of vasopressin on UT-A3 urea transporter function and hence its role in regulating urea permeability within the renal inner medullary collecting duct.