title: Increased AQP2 targeting in primary cultured IMCD cells in response to angiotensin II through AT1 receptor.
abstract: Vasopressin and angiotensin II (ANG II) play a major role in renal water and Na(+) reabsorption. We previously demonstrated that ANG II AT(1) receptor blockade decreases dDAVP-induced water reabsorption and AQP2 levels in rats, suggesting cross talk between these two peptide hormones (Am J Physiol Renal Physiol 288: F673-F684, 2005). To directly address this issue, primary cultured inner medullary collecting duct (IMCD) cells from male Sprague-Dawley rats were treated for 15 min with 1) vehicle, 2) ANG II, 3) ANG II + the AT(1) receptor blocker candesartan, 4) dDAVP, 5) ANG II + dDAVP, or 6) ANG II + dDAVP + candesartan. Immunofluorescence microscopy revealed that 10(-8) M ANG II or 10(-11) M dDAVP (protocol 1) was associated with increased AQP2 labeling of the plasma membrane and decreased cytoplasmic labeling, respectively. cAMP levels increased significantly in response to 10(-8) M ANG II and were potentiated by cotreatment with 10(-11) M dDAVP. Consistent with this finding, immunoblotting revealed that this cotreatment significantly increased expression of phosphorylated AQP2. ANG II-induced AQP2 targeting was blocked by 10(-5) M candesartan. In protocol 2, treatment with a lower concentration of dDAVP (10(-12) M) or ANG II (10(-9) M) did not change subcellular AQP2 distribution, whereas 10(-12) M dDAVP + 10(-9) M ANG II enhanced AQP2 targeting. This effect was inhibited by cotreatment with 10(-5) M candesartan. ANG II-induced cAMP accumulation and AQP2 targeting were inhibited by inhibition of PKC activity. In conclusion, ANG II plays a role in the regulation of AQP2 targeting to the plasma membrane in IMCD cells through AT(1) receptor activation and potentiates the effect of dDAVP on AQP2 plasma membrane targeting.
authors.affiliation: Dept. of Biochemistry and Cell Biology, School of Medicine, Kyungpook National Univ., Dongin-dong 101, Taegu 700-422, Korea.
authors.forename: Yu-Jung
authors.initials: YJ
authors.lastname: Lee
authors.forename: In-Kyung
authors.initials: IK
authors.lastname: Song
authors.forename: Kyung-Jin
authors.initials: KJ
authors.lastname: Jang
authors.forename: Jakob
authors.initials: J
authors.lastname: Nielsen
authors.forename: Jørgen
authors.initials: J
authors.lastname: Frøkiaer
authors.forename: Søren
authors.initials: S
authors.lastname: Nielsen
authors.forename: Tae-Hwan
authors.initials: TH
authors.lastname: Kwon
mesh_terms: D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D051399:Aquaporin 2 / Q000187:drug effects*; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002478:Cells, Cultured; D003470:Culture Media; D000242:Cyclic AMP / Q000378:metabolism; D003894:Deamino Arginine Vasopressin / Q000494:pharmacology; D004357:Drug Synergism; D016259:Genes, myc / Q000235:genetics; D007150:Immunohistochemistry; D007685:Kidney Tubules, Collecting / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D009994:Osmolar Concentration; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D044140:Receptor, Angiotensin, Type 1 / Q000187:drug effects*; D012076:Renal Agents / Q000494:pharmacology; D014162:Transfection; D014508:Urea
chemical_list: D051399:Aquaporin 2; D003470:Culture Media; D044140:Receptor, Angiotensin, Type 1; D012076:Renal Agents; D000804:Angiotensin II; D014508:Urea; D000242:Cyclic AMP; D011493:Protein Kinase C; D003894:Deamino Arginine Vasopressin