Anion channel blockers inhibit swelling-activated anion, cation, and nonelectrolyte transport in HeLa cells

Abstract

The effect of osmotic cell swelling on the permeability of HeLa cells to a range of structurally unrelated solutes including taurine, sorbitol, thymidine, choline, and K+ (96Rb+) was investigated. For each solute tested, reduction in the osmolality of the medium from 300 to 200 mosmol/kgH2O caused a significant increase in the unidirectional influx rate. In each case, the osmotically activated transport component was nonsaturable up to external substrate concentrations of 50 mM. Inhibitors of the swelling-activated anion channel of HeLa cells [quinine, 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid, niflumate, 1,9-dideoxyforskolin, 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB), and tamoxifen] blocked the osmotically activated influx of each of the different substrates tested, as well as the osmotically activated efflux of taurine and I-. Tamoxifen and NPPB were similarly effective at blocking the osmotically activated efflux of 96Rb+. The simplest of several hypotheses consistent with the data is that the osmotically activated transport of the different solutes tested here is via a swelling-activated anion-selective channel that has a significant cation permeability and a minimum pore diameter of 8-9 A.

Cell size dynamics and viability of cells exposed to hypotonic treatment and electroporation for electrofusion optimization

“…This uptake of oligosaccharides 48,49 can explain the partial inhibition of regulatory volume decrease observed in B16-F1.…”

Osmoregulation of Taurine Efflux from Cultured Human Breast Cancer Cells: Comparison with Volume Activated Cl^- Efflux and Regulation by Extracellular ATP

“…This notion is based primarily on the effect of pharmacological agents and to a lesser extent on electrophysiological evidence. The finding that volume-activated taurine efflux is inhibited by chloride channel blockers such as DIDS and NPPB was initially taken as evidence for a common pathway [5,16]. Whole-cell patch clamp studies have also shown that taurine efflux is able to permeate chloride channels [6,[17][18][19].…”

Reactive oxygen species are important mediators of taurine release from skeletal muscle cells

“…Taurine efflux from the cells was measured at room temperature (ϳ20°C), as described previously (11,19). Myotubes plated in six-well dishes were loaded with [ 14 C]taurine (30 nCi/ml) for 12 h at 37°C.…”