Urea flux across MDCK-mUT-A2 monolayers is acutely sensitive to AVP, cAMP, and [Ca2+]i.
In this study, we engineered a Madin-Darby canine kidney (MDCK) type I cell line to stably express the mouse urea transporter UT-A2. Monolayers of MDCK-mUT-A2 cells had a basal phloretin-inhibitable urea permeability of 8.4x10(-6)+/-0.3 cm/s. Treatment of MDCK-mUT-A2 monolayers with AVP led to a rapid dose-dependent increase in trans-monolayer phloretin-inhibitable urea flux. The temporal pattern of response was markedly different from that observed for MDCK cells expressing rat UT-A1. Exposure of MDCK-mUT-A2 cells to either 10 microM forskolin or 250 microM 8-bromo cAMP also increased urea flux rate. Inclusion of the PKA inhibitor H89 (10 microM) had no effect on the forskolin-stimulated increase in urea flux across MDCK-mUT-A2 monolayers. Treatment with either 10 microM CPA or 1 mM ATP also caused an increase in UT-A2-mediated urea flux, although these responses where transient compared with those induced by AVP or elevated cAMP. Taken together, these results show for the first time that UT-A2 is acutely sensitive to AVP, cAMP, or increased intracellular calcium.
Potter
Elizabeth A
EA
Faculty of Life Sciences, University of Manchester, G.38, Stopford Bldg., Oxford Road, Manchester, M13 9PT, UK.
Stewart
Gavin
G
Smith
Craig P
CP
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D001127:Arginine Vasopressin / Q000502:physiology*; D002118:Calcium / Q000502:physiology*; D002460:Cell Line; D002463:Cell Membrane Permeability / Q000502:physiology; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000502:physiology*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000502:physiology; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation; D015151:Immunoblotting; D007211:Indoles / Q000494:pharmacology; D007546:Isoquinolines / Q000494:pharmacology; D007668:Kidney / Q000737:chemistry* / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000032:analysis* / Q000235:genetics; D051379:Mice; D013449:Sulfonamides / Q000494:pharmacology; D014508:Urea / Q000378:metabolism*; D000096982:Urea Transporters
D015124:8-Bromo Cyclic Adenosine Monophosphate; D000255:Adenosine Triphosphate; D001127:Arginine Vasopressin; D002118:Calcium; D005576:Colforsin; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D004791:Enzyme Inhibitors; D007211:Indoles; D007546:Isoquinolines; D026901:Membrane Transport Proteins; D013449:Sulfonamides; D014508:Urea; D000096982:Urea Transporters; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide; C000543:cyclopiazonic acid