Volume regulation in NIH/3T3 cells not expressing P-glycoprotein. II. Chloride and amino acid fluxes.
The osmolyte function of amino acids and Cl in native NIH/3T3 cells not expressing the P-glycoprotein was examined by investigating the free amino acid concentration and the swelling-activated efflux of [3H]taurine, as representative of amino acids, and of 125I, as a tracer for Cl. Taurine and 125I efflux was activated by 20 and 30% hyposmotic solutions. At 50% hyposmotic solutions, the osmolyte pool was essentially depleted. The Cl channel blockers 5-nitro-2-(3-phenylpropyl-amino)benzoic acid, 1,9-dideoxyforskolin, dipyridamole, and niflumic acid inhibited the release of the two osmolytes by 80-95%. 4,4'-Diisothiocyanostilbene-2,2'-disulfonic acid (400 microM) decreased the efflux of taurine 80% without affecting that of 125I. Linolenic and arachidonic acids (5-20 microM) showed a concentration-dependent inhibitory effect on taurine and 125I fluxes. Omission of Ca decreased osmolyte fluxes by 16%. Verapamil inhibited the osmolyte release only at 500 microM. Nimodipine at 25 and 50 microM decreased the release of [3H]taurine and 125I by approximately 60 and 80%, respectively, but this effect was independent of the presence of extracellular Ca. These results indicate that amino acids and Cl function as osmolytes during regulatory volume decrease in native NIH/ 3T3 cells.
Morán
J
J
Institute of Cell Physiology, National University of Mexico, Mexico City, Mexico.
Miranda
D
D
Peña-Segura
C
C
Pasantes-Morales
H
H
D016475:3T3 Cells; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000502:physiology*; D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000502:physiology; D018118:Chloride Channels / Q000037:antagonists & inhibitors / Q000502:physiology*; D002712:Chlorides / Q000378:metabolism*; D005576:Colforsin / Q000031:analogs & derivatives / Q000494:pharmacology; D004176:Dipyridamole / Q000494:pharmacology; D005230:Fatty Acids, Nonesterified / Q000494:pharmacology; D007424:Intracellular Fluid / Q000502:physiology; D007457:Iodine Radioisotopes; D007700:Kinetics; D051379:Mice; D009544:Niflumic Acid / Q000494:pharmacology; D009579:Nitrobenzoates / Q000494:pharmacology; D009994:Osmolar Concentration; D013654:Taurine / Q000378:metabolism*; D014882:Water-Electrolyte Balance / Q000502:physiology*
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000596:Amino Acids; D002121:Calcium Channel Blockers; D015220:Calcium Channels; D018118:Chloride Channels; D002712:Chlorides; D005230:Fatty Acids, Nonesterified; D007457:Iodine Radioisotopes; D009579:Nitrobenzoates; D013654:Taurine; D005576:Colforsin; C058176:5-nitro-2-(3-phenylpropylamino)benzoic acid; D009544:Niflumic Acid; D004176:Dipyridamole; C047983:1,9-dideoxyforskolin; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid