Expression of a hypotonic swelling-activated Cl conductance during ontogeny of collecting duct epithelium.
Developmental expression of ion channels possibly participating in regulatory volume decrease was studied in rat embryonic (day E17) and perinatal (days P1-6) ureteric bud and in postnatal (P9-14) cortical collecting duct cells in primary monolayer culture. In isotonic bath solution, whole cell conductance (in nS/10 pF) was highest in E17 (4.0 +/- 0.5, n = 31) compared with P1-6 (2.0 +/- 0.1, n = 16) and P9-14 (1.3 +/- 0.2, n = 12) due to a decreasing contribution of a DIDS-sensitive Cl conductance, from E17 (2.8 +/- 0. 7, n = 12) to P1-6 (0.53 +/- 0.07, n = 9) and P9-14 (0.05 +/- 0.1, n = 7). Cl conductance in E17 exhibited a permselectivity of I approximately Cl approximately Br >> gluconate, and it activated time dependently. Hypotonic bath solution induced a large increase of whole cell conductance in P1-6 and in P9-14 but not in E17 (by 20. 0 +/- 3.7, 21.5 +/- 5.5, and 4.9 +/- 1.7; n = 11, 12, and 25, respectively) due to the activation of a time-dependently inactivating Cl conductance with a permselectivity of I >/= Br > Cl >> gluconate. In conclusion, the expression of Cl channels, as studied in vitro, appears to shift from an apparently constitutively active embryonic to a hypotonic swelling-activated type during late embryonic development of the collecting duct.
Physiologisches Institut, Ludwig-Maximilians-Universität, 80336 Munich, Germany.
S M
SM
Huber
M F
MF
Horster
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000375:Aging / Q000502:physiology*; D000818:Animals; D000831:Animals, Newborn; D000838:Anions / Q000378:metabolism; D018118:Chloride Channels / Q000187:drug effects / Q000502:physiology*; D002712:Chlorides / Q000494:pharmacology; D004533:Egtazic Acid / Q000494:pharmacology; D004553:Electric Conductivity; D005314:Embryonic and Fetal Development / Q000502:physiology*; D004847:Epithelial Cells / Q000502:physiology* / Q000648:ultrastructure; D004848:Epithelium / Q000196:embryology / Q000254:growth & development; D007038:Hypotonic Solutions; D007685:Kidney Tubules, Collecting / Q000196:embryology / Q000254:growth & development / Q000502:physiology*; D008564:Membrane Potentials; D008855:Microscopy, Electron, Scanning; D009994:Osmolar Concentration; D051381:Rats; D014513:Ureter / Q000196:embryology / Q000254:growth & development / Q000502:physiology
D000838:Anions; D018118:Chloride Channels; D002712:Chlorides; D007038:Hypotonic Solutions; D004533:Egtazic Acid; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid