title: Disparity between ionic mediators of volume regulation and apoptosis in N1E 115 mouse neuroblastoma cells.
abstract: Cellular volume loss or shrinkage is a ubiquitous feature of apoptosis and thus may contribute to this form of degeneration. Chloride (Cl(-)) and potassium (K(+)) efflux has been shown to participate in volume regulation and several recent reports have implicated K(+) efflux in apoptotic neuronal death. Here pharmacological inhibitors of various K(+) and Cl(-) channels and transporters were used to decipher the relationship between cellular volume regulation and apoptosis. Following exposure to a hypotonic media, cells swell but over time gradually recover, returning to their original cell volume in a process known as regulatory volume decrease (RVD). RVD in N1E 115 neuroblastoma cells was monitored using time-lapse videomicroscopy, cell size and DNA degradation were followed using flow cytometry and fragmented apoptotic nuclei were visualized using Hoechst staining. RVD was blocked by high K(+), TEA and 4-AP (K(+) channel blockers), DIDS and niflumic acid but not SITS (Cl(-) channel blockers), ethacrynic acid (Cl(-) pump blocker), bumetanide (Na(+)/K(+)/Cl(-) cotransporter blocker) and furosemide (K(+)/Cl(-) cotransport blocker). In contrast, only DIDS and SITS (blockers of the Cl(-)/HCO(3) exchanger) inhibited apoptosis, suggesting that a common mechanistic link between RVD and apoptosis is the Cl(-)/HCO(3) exchanger. Thus, this study does not support the notion that K(+) channels are universal anti-apoptotic targets. Instead, the Cl(-)/HCO(3) exchanger may prove to be a viable target of therapeutic intervention for treating pathological apoptosis and neurodegeneration.
authors.affiliation: Institute for Biological Sciences, National Research Council, Ottawa, Ontario, Canada.
authors.forename: Natasha
authors.initials: N
authors.lastname: O'Reilly
authors.forename: Zhenlei
authors.initials: Z
authors.lastname: Xia
authors.forename: Hawley
authors.initials: H
authors.lastname: Fiander
authors.forename: Joseph
authors.initials: J
authors.lastname: Tauskela
authors.forename: Daniel L
authors.initials: DL
authors.lastname: Small
mesh_terms: D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D002034:Bumetanide / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D048429:Cell Size / Q000187:drug effects / Q000502:physiology; D002490:Central Nervous System / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D018118:Chloride Channels / Q000037:antagonists & inhibitors / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005665:Furosemide / Q000494:pharmacology; D007473:Ion Channels / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D009447:Neuroblastoma; D019636:Neurodegenerative Diseases / Q000188:drug therapy / Q000378:metabolism* / Q000503:physiopathology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D009544:Niflumic Acid / Q000494:pharmacology; D026902:Potassium Channel Blockers / Q000494:pharmacology; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism; D011189:Potassium Chloride / Q000494:pharmacology; D049994:Sodium Potassium Chloride Symporter Inhibitors; D028021:Sodium-Potassium-Chloride Symporters / Q000378:metabolism; D019311:Staurosporine / Q000494:pharmacology; D014407:Tumor Cells, Cultured
chemical_list: D018118:Chloride Channels; D004791:Enzyme Inhibitors; D007473:Ion Channels; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D049994:Sodium Potassium Chloride Symporter Inhibitors; D028021:Sodium-Potassium-Chloride Symporters; D002034:Bumetanide; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D009544:Niflumic Acid; D011189:Potassium Chloride; D005665:Furosemide; D019311:Staurosporine; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid