title: Cl- influx into rat cortical lens fiber cells is mediated by a Cl- conductance that is not ClC-2 or -3.
abstract: OBJECTIVE
  Exposure of organ-cultured lenses to Cl(-) channel blockers under isotonic conditions induces a localized cortical zone of extracellular space dilations. The purpose of this study was to investigate whether elongated lens fiber cells from this zone contain an anion conductance that mediates Cl(-) influx and whether two chloride channel isoforms known to be expressed in the lens (ClC-2 and -3) are responsible.
  
  
  METHODS
  Fiber cells were isolated by enzymatic dissociation in the presence of Gd(3+) and Co(2+) and their electrical properties analyzed by whole-cell patch clamping. Cells from the zone of extracellular space dilations were selected for analysis on the basis of cell length. RT-PCR and immunocytochemistry were used to determine whether ClC-2 or -3 channel isoforms are expressed in fiber cells located in the zone of extracellular space dilations.
  
  
  RESULTS
  Cells from the zone of extracellular space dilations were typically >120 microm in length and exhibited an outwardly rectifying Cl(-) conductance that was blocked by DIDS (4,4'-diisothiocyanostilbene-2,2'-disulfonic acid) and displayed an anion selectivity sequence of I(-) > Cl(-) >> gluconate. ClC-2 and -3 were found to be expressed at the transcript and protein level in lens fiber cells, but subsequent immunocytochemical studies indicated that expressed proteins did not colocalize with cell membranes in the zone of extracellular space dilations, being predominately cytoplasmic in nature.
  
  
  CONCLUSIONS
  Taken together, the data indicate that extracellular space dilations are due to the inhibition of a Cl(-) channel(s) that normally mediates Cl(-) influx into cortical lens fiber cells under isotonic conditions. The molecular identity of this channel remains to be determined.
authors.affiliation: Department of Physiology, School of Medical Sciences, University of Auckland, Auckland, New Zealand.
authors.forename: Kevin F
authors.initials: KF
authors.lastname: Webb
authors.forename: B Rachelle
authors.initials: BR
authors.lastname: Merriman-Smith
authors.forename: Jonelle K
authors.initials: JK
authors.lastname: Stobie
authors.forename: Joerg
authors.initials: J
authors.lastname: Kistler
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Donaldson
mesh_terms: D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000818:Animals; D000090007:CLC-2 Chloride Channels; D002470:Cell Survival; D018118:Chloride Channels / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000502:physiology; D002712:Chlorides / Q000378:metabolism*; D005110:Extracellular Space; D007150:Immunohistochemistry; D007904:Lens Cortex, Crystalline / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D008564:Membrane Potentials; D018408:Patch-Clamp Techniques; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D000090007:CLC-2 Chloride Channels; D018118:Chloride Channels; D002712:Chlorides; C115376:ClC-3 channel; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid