Separate taurine and chloride efflux pathways activated during regulatory volume decrease
- 1 September 1999
- journal article
- research article
- Published by American Physiological Society in American Journal of Physiology-Cell Physiology
- Vol. 277 (3), C392-C402
- https://doi.org/10.1152/ajpcell.1999.277.3.c392
Abstract
Organic osmolyte and halide permeability pathways activated in epithelial HeLa cells by cell swelling were studied by radiotracer efflux techniques and single-cell volume measurements. The replacement of extracellular Cl−by anions that are more permeant through the volume-activated Cl−channel, as indicated by electrophysiological measurements, significantly decreased taurine efflux. In the presence of less-permeant anions, an increase in taurine efflux was observed. Simultaneous measurement of the125I, used as a tracer for Cl−, and [3H]taurine efflux showed that the time courses for the two effluxes differed. In Cl−-rich medium the increase in I−efflux was transient, whereas that for taurine was sustained. Osmosensitive Cl−conductance, assessed by measuring changes in cell volume, increased rapidly after hypotonic shock. The influx of taurine was able to counteract Cl−conductance-dependent cell shrinkage but only ∼4 min after triggering cell swelling. This taurine-induced effect was blocked by DIDS. Differences in anion sensitivity, the time course of activation, and sensitivity to DIDS suggest that the main cell swelling-activated permeability pathways for taurine and Cl−are separate.Keywords
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