title: Inhibitory effect of DIDS, NPPB, and phloretin on intracellular chloride channels.
abstract: We studied the effects of the chloride channel blockers, 5-nitro-2-(phenylpropylamino)-benzoate (NPPB), dihydro-4,4' diisothiocyanostilbene-2,2'-disulphonic acid (DIDS), and phloretin on H2O2-induced primary culture cardiomyocyte apoptosis and activity of intracellular chloride channels obtained from rat heart mitochondrial and lysosomal vesicles. The chloride channel blockers (100 micromol/l) inhibited the H2O2-induced cardiomyocytes apoptosis. We characterized the effect of the blockers on single channel properties of the chloride channels derived from the mitochondrial and lysosomal vesicles incorporated into a bilayer lipid membrane. The single chloride channel currents were measured in 250:50 mmol/l KCl cis/trans solutions. NPPB, DIDS, and phloretin inhibited the chloride channels by decreasing the channel open probability in a concentration-dependent manner with EC50 values of 42, 7, and 20 micromol/l, respectively. NPPB and phloretin inhibited the channel's conductance and open dwell time, indicating that they could affect the chloride selective filter, pore permeability, and gating mechanism of the chloride channels. DIDS and NPPB inhibited the channels from the other side than bongkrekic acid and carboxyatractyloside. The results may contribute to understand a possible involvement of intracellular chloride channels in apoptosis and cardioprotection.
authors.affiliation: Institute of Molecular Physiology and Genetics, Centre of Excellence for Cardiovascular Research, Slovak Academy of Sciences, Vlarska 5, 833 34 Bratislava, Slovak Republic.
authors.forename: Lubica
authors.initials: L
authors.lastname: Malekova
authors.forename: Jana
authors.initials: J
authors.lastname: Tomaskova
authors.forename: Marie
authors.initials: M
authors.lastname: Novakova
authors.forename: Peter
authors.initials: P
authors.lastname: Stefanik
authors.forename: Juraj
authors.initials: J
authors.lastname: Kopacek
authors.forename: Boris
authors.initials: B
authors.lastname: Lakatos
authors.forename: Silvia
authors.initials: S
authors.lastname: Pastorekova
authors.forename: Olga
authors.initials: O
authors.lastname: Krizanova
authors.forename: Albert
authors.initials: A
authors.lastname: Breier
authors.forename: Karol
authors.initials: K
authors.lastname: Ondrias
mesh_terms: D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology*; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002478:Cells, Cultured; D018118:Chloride Channels / Q000037:antagonists & inhibitors* / Q000187:drug effects / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004594:Electrophysiology; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008247:Lysosomes / Q000378:metabolism; D008297:Male; D008929:Mitochondria, Heart / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000166:cytology / Q000187:drug effects*; D009579:Nitrobenzoates / Q000494:pharmacology*; D010693:Phloretin / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D018118:Chloride Channels; D009579:Nitrobenzoates; C058176:5-nitro-2-(3-phenylpropylamino)benzoic acid; D006861:Hydrogen Peroxide; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D010693:Phloretin