title: Fluid transport in a cultured cell model of kidney epithelial cyst enlargement.
abstract: Madin-Darby canine kidney (MDCK) cells, when seeded into collagen gel, from polarized, spherical, epithelial cysts, which grow by a process involving fluid secretion and cell proliferation. These cysts are a useful model for understanding the dynamics of cyst enlargement in renal cystic disease. The hypothesis that MDCK cyst fluid secretion depends upon chloride secretion was tested, and a cell model for this process is presented here. Lumen and epithelial cell volumes were measured by video microscopy in acute experiments. Fluid absorption (-0.073 +/- 0.007 microliters.h-1.cm-2; N = 8) was observed when cysts were superfused with unsupplemented Dublecco's modified Eagle's medium at 36 to 37 degrees C. Fluid secretion (0.221 +/- 0.0016 microliters.h-1.cm-2; N = 25) was seen when 1 mM dibutyryl cAMP plus 0.1 mM 3-isobutyl-1-methylxanthine were added to the superfusate. cAMP-induced fluid secretion was significantly inhibited by basolateral 1 mM ouabain, 0.1 mM furosemide, or 1 mM amiloride. It was not significantly affected by 1 mM chlorothiazide, 0.01 mM bumetanide, or 0.1 mM acetazolamide in the presence of normal bicarbonate/CO2. In the nominal absence of bicarbonate/CO2 fluid secretion was 18% of control. Vasopressin-induced fluid secretion was significantly inhibited by pretreatment of cysts with 0.1 mM 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS). Cyst cell shrinkage in isosmotic chloride-free Ringer's solution (chloride replaced by gluconate) was inhibited by 0.1 mM basolateral DIDS. The results suggest that chloride-bicarbonate exchange in the basolateral membrane of MDCK cyst epithelial cells plays a critical role in cyst fluid secretion.
authors.affiliation: Department of Physiology & Biophysics, Indiana University School of Medicine, Indianapolis 46202-5120.
authors.forename: G A
authors.initials: GA
authors.lastname: Tanner
authors.forename: M R
authors.initials: MR
authors.lastname: Maxwell
authors.forename: J A
authors.initials: JA
authors.lastname: McAteer
mesh_terms: D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D000086:Acetazolamide / Q000494:pharmacology; D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D001639:Bicarbonates / Q000378:metabolism / Q000494:pharmacology; D001692:Biological Transport / Q000187:drug effects; D003994:Bucladesine / Q000494:pharmacology; D002034:Bumetanide / Q000494:pharmacology; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D002712:Chlorides / Q000378:metabolism; D002740:Chlorothiazide / Q000494:pharmacology; D046508:Culture Techniques / Q000379:methods; D004285:Dogs; D007424:Intracellular Fluid / Q000378:metabolism*; D007668:Kidney / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D052177:Kidney Diseases, Cystic; D051379:Mice; D010042:Ouabain / Q000494:pharmacology; D012996:Solutions / Q000378:metabolism
chemical_list: D001639:Bicarbonates; D002712:Chlorides; D012996:Solutions; D002034:Bumetanide; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D010042:Ouabain; D003994:Bucladesine; D002740:Chlorothiazide; D000584:Amiloride; D000086:Acetazolamide; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D015056:1-Methyl-3-isobutylxanthine