Passive potassium transport in low potassium sheep red cells: dependence upon cell volume and chloride.

Dunham, Philip B.; Ellory, J. C.

doi:10.1113/jphysiol.1981.sp013881

Cited by 240 publications

(184 citation statements)

References 43 publications

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“…LK sheep red cells are the more unusual in having a high passive K¤ 'leak' coupled with a small active K¤ uptake through the Na¤,K¤-ATPase (Tosteson & Hoffman, 1960); the reverse pertains for HK red cells. The large K¤ 'leak' in LK red cells is, in fact, a very specific anion-dependent transporter, exquisitely sensitive to volume, pH and urea (Dunham & Ellory, 1981;Lauf et al 1992 ;Dunham, 1995). It is almost certainly via the KCl cotransporter, recently cloned from human, rat and rabbit tissues (Gillen, Brill, Payne & Forbush, 1996).…”

Section: Discussionmentioning

confidence: 99%

“…For experiments in which Cl¦ dependence of K¤ influx was examined, Cl¦ was substituted with NO×¦ -it is widely assumed that Cl¦-dependent K¤ fluxes are mediated via a KCl cotransporter (e.g. Dunham & Ellory, 1981) and this interpretation is followed here. The possibility of a Cl¦-activated K¤ transporter, however, cannot be excluded.…”

Section: Saline Solutionsmentioning

confidence: 99%

“…K¤ influx was measured at 37°C by conventional radioactive tracer techniques using ÌÉRb¤ (DuPont-NEN, Bad Homburg, Germany) as a tracer for K¤ (Dunham & Ellory, 1981;Gibson, Ellory, Culliford & Fincham, 1993). Ouabain (final concentration, 100 ìÒ) was present in all experiments, obviating any K¤ influx through the Na¤,K¤-ATPase.…”

Section: K¤ Influxmentioning

confidence: 99%

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Oxygen‐dependent K⁺ fluxes in sheep red cells

Campbell

Gibson

1998

The Journal of Physiology

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This study was designed to investigate the O2 dependence of K+ influx in sheep red cells. Influx was determined using 86Rb+ as a tracer for K+; glass tonometers coupled to a gas mixing pump were used to equilibrate cell samples to the requisite oxygen tension (PO2). Both volume‐ and H+‐stimulated K+ influxes in low potassium‐containing (LK) sheep red cells were approximately doubled on equilibration with O2 relative to influxes measured in N2. O2‐dependent influxes were abolished when Cl− was replaced with NO3−, consistent with mediation by the KCl cotransporter. At pH 7, PO2 required for half‐maximal stimulation was 56 ± 1 mmHg (mean ± s.e.m., 3 sheep) for the O2‐dependent component of K+ influx: thus PO2 values over the physiological range affected K+ influx. K+ influx in fully deoxygenated sheep red cells showed substantial volume and H+ sensitivity. These residual components in N2 were also Cl− dependent, indicating that the KCl cotransporter of LK sheep red cells was active in the absence of O2. Volume‐sensitive K+ influxes in high potassium‐containing (HK) sheep red cells responded in a similar way to those in cells from LK sheep, although much smaller in magnitude, showing that intracellular [K+] had no significant effect on the O2 dependence of the cotransporter. Intracellular [Mg2+] ([Mg2+]i) was altered by incubating sheep red cells with A23187 (20 μM) and different values of extracellular [Mg2+] ([Mg2+]o). Total [Mg2+]i was determined by atomic absorption spectroscopy and free [Mg2+]i from [Mg2+]o and the Donnan ratio. Total [Mg2+]i was 1.29 ± 0.08 mM (mean ± s.e.m., n= 5), similar to that reported in the literature. Estimates of free [Mg2+]i showed an increase from 0.39 ± 0.05 in oxygenated cells to 0.52 ± 0.04 mM (mean ± s.e.m., n= 5; P < 0.05) in deoxygenated ones. Finally, although K+ influxes were altered by pharmacological loading or depletion of cells with Mg2+, the free [Mg2+]i required to affect influxes significantly was outside the physiological range. Results are difficult to reconcile with PO2 modulating KCl cotransport activity directly via changes in free [Mg2+]i or [Mg2+‐ATP]i.

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Section: Discussionmentioning

confidence: 99%

Section: Saline Solutionsmentioning

confidence: 99%

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Oxygen‐dependent K⁺ fluxes in sheep red cells

Campbell

Gibson

1998

The Journal of Physiology

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“…This phenomenon, namely 'regulatory volume decrease' (RVD), was subsequently found in erythrocytes from other species, including man (Dunham & Ellory, 1981;Lauf, Adragna & Garay, 1984; Garay, Nazaret, Hannaert & Cragoe, 1988), in Ehrlich ascites tumour cells (Hoffman, Simonsen & Dunham, 1984;Thornhill & Laris, 1984), in lymphocytes (for review see Grinstein, Rothstein, Sarkadi & Gelfand, 1984;Grinstein & Dixon, 1989) and in several other cells (for review see Hoffman & Simonsen, 1989;Lauf, anion carrier (Brazy & Gunn, 1976: Garay, Hannaert, Nazaret & Cragoe, 1986).…”

Section: Introductionmentioning

confidence: 99%

Volume‐dependent K+ and Cl‐ fluxes in rat thymocytes.

Soler

Rota

Hannaert

et al. 1993

The Journal of Physiology

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SUMMARY1. Hypotonic stress unmasked inward and outward K+ and Cl-movements in rat thymocytes. This KCl flux stimulation was reduced by DIOA (dihydroindenyl-oxyalkanoic 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-'), the cells exhibited the following DIOA-(ii) a Cl-efflux of 68 + 21 mmol (I cells. h)-1 (n = 3), (iii) a Rb+ influx of 9-7 + 3 9 mmol (1 cells.h)-1 (n = 6) and (iv) a Cl-influx of 94+4-1 mmol (1 cells.h)-1 (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-'). Inhibition of DIOA-sensitive 36C1-efflux by cell K+ depletion suggested coupling of outward K+ and Cl-fluxes. Conversely, inward K+ and Clfluxes 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+-Clco-transport system which is strongly activated by hypotonic shock and catalyses net KCl extrusion.

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“…Here it can be seen that influx was high. The high K + content of red blood cells means that this system will mediate KCl loss at about 10-fold greater rates (Dunham & Ellory, 1981). On deoxygenation, KCC activity remained at substantial levels.…”

Section: The Main Cation Transport In Red Blood Cells From Sickle Celmentioning

confidence: 94%