title: Sodium is not required for chloride efflux via chloride/bicarbonate exchanger from rat thymic lymphocytes.
abstract: Sodium-dependent Cl(-)/HCO3 (-) exchanger acts as a chloride (Cl(-)) efflux in lymphocytes. Its functional characterization had been described when Cl(-) efflux was measured upon substituting extracellular sodium (Na(+)) by N-methyl-D-glucamine (NMDG). For Na(+) and Cl(-) substitution, we have used D-mannitol or NMDG. Thymocytes of male Wistar rats aged 7-9 weeks were used and intracellular Cl(-) was measured by spectrofluorimetry using MQAE dye in bicarbonate buffers. Chloride efflux was measured in a Cl(-)-free buffer (Cl(-) substituted with isethionate acid) and in Na(+) and Cl(-)-free buffer with D-mannitol or with NMDG. The data have shown that Cl(-) efflux is mediated in the absence of Na(+) in a solution containing D-mannitol and is inhibited by H2DIDS. Mathematical modelling has shown that Cl(-) efflux mathematical model parameters (relative membrane permeability, relative rate of exchanger transition, and exchanger efficacy) were the same in control and in the medium in which Na(+) had been substituted by D-mannitol. The net Cl(-) efflux was completely blocked in the NMDG buffer. The same blockage of Cl(-) efflux was caused by H2DIDS. The study results allow concluding that Na(+) is not required for Cl(-) efflux via Cl(-)/HCO3 (-) exchanger. NMDG in buffers cannot be used for substituting Na(+) because NMDG inhibits the exchanger.
authors.affiliation: Institute of Oncology, Vilnius University, Baublio Street 3b, 08660 Vilnius, Lithuania ; Mykolas Romeris University, Ateities Street 21, 08303 Vilnius, Lithuania.
authors.forename: Donatas
authors.initials: D
authors.lastname: Stakišaitis
authors.affiliation: Institute of Oncology, Vilnius University, Baublio Street 3b, 08660 Vilnius, Lithuania.
authors.forename: Vaidevutis
authors.initials: V
authors.lastname: Meilus
authors.affiliation: Institute of Oncology, Vilnius University, Baublio Street 3b, 08660 Vilnius, Lithuania.
authors.forename: Alfonsas
authors.initials: A
authors.lastname: Juška
authors.affiliation: Lithuanian University of Health Sciences, Veterinary Academy, Mickevičiaus Street 9, 44307 Kaunas, Lithuania.
authors.forename: Paulius
authors.initials: P
authors.lastname: Matusevičius
authors.affiliation: Institute of Oncology, Vilnius University, Baublio Street 3b, 08660 Vilnius, Lithuania.
authors.forename: Janina
authors.initials: J
authors.lastname: Didžiapetrienė
mesh_terms: D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D027963:Chloride-Bicarbonate Antiporters / Q000378:metabolism*; D002712:Chlorides / Q000378:metabolism*; D008214:Lymphocytes / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008536:Meglumine / Q000494:pharmacology; D008954:Models, Biological; D017208:Rats, Wistar; D012964:Sodium / Q000378:metabolism*; D013950:Thymus Gland / Q000166:cytology*
chemical_list: D027963:Chloride-Bicarbonate Antiporters; D002712:Chlorides; C018564:dihydro-DIDS; D008536:Meglumine; D012964:Sodium; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid