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Volume‐dependent K+ and Cl‐ fluxes in rat thymocytes.
Author(s) -
Soler A,
Rota R,
Hannaert P,
Cragoe E J,
Garay R P
Publication year - 1993
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1993.sp019682
Subject(s) - chemistry , dids , ouabain , stimulation , efflux , biophysics , bumetanide , cotransporter , tonicity , sodium , ion transporter , medicine , endocrinology , biochemistry , membrane , biology , organic chemistry
1. Hypotonic stress unmasked inward and outward K+ and Cl‐ movements in rat thymocytes. This KCl flux stimulation was reduced by DIOA (dihydroindenyl‐oxy‐alkanoic acid), but not by DIDS (4,4'‐diisothiocyanostilbene‐2,2'‐disulphonate), quinidine, DPAC 144 (5‐nitro‐2‐(2‐phenylethyl‐amino)‐benzoic acid), bumetanide or ouabain. 2. In isotonic media (308 +/‐ 5 mosmol kg‐1), the cells exhibited the following DIOA‐sensitive fluxes: (i) a K+ efflux of 42.7 +/‐ 17.1 mmol (l cells.h)‐1 (mean +/‐ S.D., n = 7), (ii) a Cl‐ efflux of 68 +/‐ 21 mmol (l cells.h)‐1 (n = 3), (iii) a Rb+ influx of 9.7 +/‐ 3.9 mmol (l cells.h)‐1 (n = 6) and (iv) a Cl‐ influx of 9.4 +/‐ 4.1 mmol (l cells.h)‐1 (n = 6). 3. Hypotonic shock (183‐200 mosmol kg‐1) induced a sevenfold stimulation of DIOA‐sensitive K+ and Cl‐ effluxes and a twofold stimulation of DIOA‐sensitive Rb+ and Cl‐ influxes (with a Rb+ to Cl‐ stoichiometry of 1.04 +/‐ 0.31; mean +/‐ S.D., n = 6). 4. The DIOA‐sensitive membrane carrier catalysed net outward KCl extrusion (the outward/inward flux ratio was 5‐7 in isotonic media and 20 in hypotonic media at 189 mosmol kg‐1). Inhibition of DIOA‐sensitive 36Cl‐ efflux by cell K+ depletion suggested coupling of outward K+ and Cl‐ fluxes. Conversely, inward K+ and Cl‐ fluxes were found to be uncoupled in NO3‐ media and in K(+)‐free media. 5. The results clearly show that rat thymocyte membranes possess a 1:1 K(+)‐Cl‐ co‐transport system which is strongly activated by hypotonic shock and catalyses net KCl extrusion.

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