PMU-Autor/inn/en
Paulmichl MarkusAbstract
1. In NIH3T3 fibroblasts, the chloride channel involved in regulatory volume decrease (RVD) was identified as ICln, a protein isolated from a cDNA library derived from Madin Darby canine Kidney (MDCK) cells. ICln expressed in Xenopus laevis oocytes gives rise to an outwardly rectifying chloride current, sensitive to the extracellular addition of nucleotides and the known chloride channel blockers, DIDS (4,4"-diisothiocyanatostilbene-2,2"-disulphonic acid) and NPPB (5-nitro-2-(3-phenylpropylamino)-benzoic acid). We set out to study whether substances structurally similar to NPPB are able to interfere with RVD. 2. RVD in NIH3T3 fibroblasts and MDCK cells is temperature-dependent. 3. RVD, the swelling-dependent chloride current and the depolarization seen after reducing extracellular osmolarity can be blocked by gossypol and NDGA (nordihydroguaiaretic acid), both structurally related to NPPB. 4. The cyclic AMP-dependent chloride current elicited in CaCo cells is less sensitive to the two substances tested while the calcium-activated chloride current in fibroblasts is insensitive. 5. The binding site for the two phenol derivatives onto ICln seems to be distinct but closely related to the nucleotide binding site identified as G x G x G, a glycine repeat located at the predicted outer mouth of the ICln channel protein.
Useful keywords (using NLM MeSH Indexing)
3T3 Cells/cytology
3T3 Cells/drug effects
Animals
Binding Sites
Caco-2 Cells/cytology
Caco-2 Cells/drug effects
Calcium/physiology
Cell Size/drug effects
Cell Size/physiology
Chloride Channels/antagonists*
inhibitors*
Chloride Channels/physiology*
Chlorides/metabolism
Chlorides/physiology
Cyclic AMP/physiology
Dogs
Gossypol/pharmacology
Humans
Kidney/cytology
Kidney/drug effects
Membrane Potentials/drug effects
Mice
Nordihydroguaiaretic Acid/pharmacology
Phenols/pharmacology*
Thymine Nucleotides/pharmacology
Xenopus laevis
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