Volume-associated osmolyte fluxes in cell lines with or without the anion exchanger. S[acute]anchez-Olea, R., C. Fuller, D. Benos, and H. Pasantes-Morales. Instituto de Fisiolog[acute]ia Celular, UNAM, Mexico D.F., Mexico, Department of Physiology and Biophysics, The University of Alabama at Birmingham, Alabama, USA.
APStracts 2:0236C, 1995.
In order to investigate the involvement of a red cell type anion exchanger in the volume-sensitive amino acid release, the hyposmolarity-evoked release of [3H]D-aspartate and [3H]taurine was examined in three cell lines: 1) the wild type chinese hamster ovary (CHO K1) cells, expressing an anion exchanger activity (Cl-/SO42-) functionally similar to the erythroid band 3, 2) a mutant CHO cell type (CHO 605) lacking this anion exchanger activity, and 3) 293 cells in which the Cl-/HCO3- anion exchanger is absent. All cell types accumulated 3[H]D-aspartate and [3H]taurine under isosmotic conditions and similarly in the three cell lines, cell swelling evoked by hyposmolarity induced a rapid and transient increase in the amino acid efflux. Blockers of the anion exchanger and/or chloride channels (niflumic acid, dipyridamole, DPC, NPPB and DIDS) were potent inhibitors of amino acid efflux in the three cell lines. 125I- efflux, used as a marker for chloride fluxes, was also markedly increased in response to cell swelling in all cell lines and this efflux was inhibited by the anion exchanger/chloride channel blockers. These results do not support a role for an anion exchanger in the hyposmolarity-induced amino acid efflux, and suggest that amino acids and chloride may be transported by the same or a similar mechanism, presumably an anion channel-like structure. 

Received 14 March 1994; accepted in final form 2 June 1995.
APS Manuscript Number C134-4.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on  6 July 1995.