title: Activation of potassium and chloride channels by tumor necrosis factor alpha. Role in liver cell death.
abstract: Despite abundant evidence for changes in mitochondrial membrane permeability in tumor necrosis factor (TNF)-mediated cell death, the role of plasma membrane ion channels in this process remains unclear. These studies examine the influence of TNF on ion channel opening and death in a model rat liver cell line (HTC). TNF (25 ng/ml) elicited a 2- and 5-fold increase in K(+) and Cl(-) currents, respectively, in HTC cells. These increases occurred within 5-10 min after TNF exposure and were inhibited either by K(+) or Cl(-) substitution or by K(+) channel blockers (Ba(2+), quinine, 0.1 mm each) or Cl(-) channel blockers (10 microm 5-nitro-2-(3-phenylpropylamino)benzoic acid and 0.1 mm N-phenylanthranilic acid), respectively. TNF-mediated increases in K(+) and Cl(-) currents were each inhibited by intracellular Ca(2+) chelation (5 mm EGTA), ATP depletion (4 units/ml apyrase), and the protein kinase C (PKC) inhibitors chelerythrine (10 micrometer) or PKC 19-36 peptide (1 micrometer). In contrast, currents were not attenuated by the calmodulin kinase II 281-309 peptide (10 micrometer), an inhibitor of calmodulin kinase II. In the presence of actinomycin D (1 micrometer), each of the above ion channel blockers significantly delayed the progression to TNF-mediated cell death. Collectively, these data suggest that activation of K(+) and Cl(-) channels is an early response to TNF signaling and that channel opening is Ca(2+)- and PKC-dependent. Our findings further suggest that K(+) and Cl(-) channels participate in pathways leading to TNF-mediated cell death and thus represent potential therapeutic targets to attenuate liver injury from TNF.
authors.affiliation: Department of Medicine, Pharmacology, and Anatomy and Neurobiology, University of Vermont, Burlington, Vermont 05401, USA.
authors.forename: H H
authors.initials: HH
authors.lastname: Nietsch
authors.forename: M W
authors.initials: MW
authors.lastname: Roe
authors.forename: J F
authors.initials: JF
authors.lastname: Fiekers
authors.forename: A L
authors.initials: AL
authors.lastname: Moore
authors.forename: S D
authors.initials: SD
authors.lastname: Lidofsky
mesh_terms: D000470:Alkaloids; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D001464:Barium / Q000494:pharmacology; D053119:Benzophenanthridines; D002118:Calcium / Q000494:pharmacology; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000494:pharmacology; D018118:Chloride Channels / Q000187:drug effects / Q000378:metabolism*; D002712:Chlorides / Q000378:metabolism; D003609:Dactinomycin / Q000494:pharmacology; D004533:Egtazic Acid / Q000494:pharmacology; D007473:Ion Channels / Q000819:agonists / Q000037:antagonists & inhibitors; D008099:Liver / Q000378:metabolism*; D009579:Nitrobenzoates / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D010617:Phenanthridines / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D011803:Quinine; D051381:Rats; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D062367:ortho-Aminobenzoates / Q000494:pharmacology
chemical_list: D000470:Alkaloids; D053119:Benzophenanthridines; D018118:Chloride Channels; D002712:Chlorides; D007473:Ion Channels; D009579:Nitrobenzoates; D010617:Phenanthridines; D015221:Potassium Channels; D014409:Tumor Necrosis Factor-alpha; D062367:ortho-Aminobenzoates; D003609:Dactinomycin; D001464:Barium; C058176:5-nitro-2-(3-phenylpropylamino)benzoic acid; D004533:Egtazic Acid; C001209:fenamic acid; D011803:Quinine; C016299:chelerythrine; D011493:Protein Kinase C; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D011188:Potassium; D002118:Calcium