Regulatory volume decrease in lamprey erythrocytes: mechanisms of K+ and Cl- loss

1995 ◽  
Vol 268 (3) ◽  
pp. R590-R597
Author(s):  
L. V. Virkki ◽  
M. Nikinmaa
Keyword(s):  
Acetic Acid ◽  
Regulatory Volume Decrease ◽  
Cell Swelling ◽  
Disulfonic Acid ◽  
Minor Effect ◽  
Transport Pathways ◽  
Cl Transport ◽  
Medium Osmolarity ◽  
A Minor ◽  
Volume Decrease

The nature of the swelling-activated K+ and Cl- transport pathways of lamprey (Lampetra fluviatilis) erythrocytes was studied. In isosmotic medium, unidirectional K+ and Cl- effluxes appear to be largely mediated by conductive pathways. Unidirectional Cl- efflux increased as a function of a decrease in medium osmolarity. The swelling-activated Cl- transport was inhibited by R(+)-[(2-n-butyl-6,7-dichloro-2-cyclopentyl-2,3-dihydro-1-oxo-1H-inde n-5- yl)oxy]acetic acid (DIOA), furosemide, and 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS). In contrast, moderate cell swelling did not increase unidirectional ouabain-insensitive K+ efflux. However, inhibition of transport by Ba2+ was markedly reduced. This suggests that the Ba(2+)-sensitive pathway that mediated most of the K+ efflux in isosmotic conditions was inhibited by cell swelling and a Ba(2+)-insensitive pathway was activated. DIOA had no effect on K+ efflux in isosmotic or hyposmotic medium. These data and the finding that substitution of NO3- or SCN- for Cl- had only a minor effect on the swelling-induced net extrusion of K+ and water indicate that the pathways for K+ and Cl-, activated by cell swelling, are conductive.

Separate K+ and Cl- transport pathways are activated for regulatory volume decrease in jejunal villus cells

1991 ◽  
Vol 260 (3) ◽  
pp. G405-G415 ◽  
Author(s):  
R. J. MacLeod ◽  
J. R. Hamilton
Keyword(s):  
Regulatory Volume Decrease ◽  
Cell Swelling ◽  
Disulfonic Acid ◽  
Transport Pathways ◽  
Kg Medium ◽  
Cell Sizing ◽  
Rate Limiting ◽  
Li Substitution ◽  
Hypotonic Swelling ◽  
Volume Decrease

We assessed ion transport mechanisms operative during regulatory volume decrease (RVD) in jejunal villus enterocytes, isolated in suspension from guinea pig jejunum and examined with electronic cell sizing. Immediately after reduction of osmolarity (153 mosmol/kg medium) enterocytes swelled, but within 5 min they shrank by 50%. This RVD, which was complete by 20 min, was unaffected by Li+ substitution for Na+ or by Na(+)-free (N-methyl-D-glucose, NMDG+) medium. Passive loss of K+ is required for RVD because both the magnitude and direction of RVD changed when external [K+] varied. Increasing K+ permeability with gramicidin (0.5 microM) accelerated RVD in NMDG+ medium (10.0 +/- 0.8 vs. 6.2 +/- 0.4% min-1, P less than 0.01) suggesting that K+ loss is rate limiting for RVD. Inhibition of K(+)- and Ca2(+)-activated K+ conductance with Ba2+ (5 mM, P less than 0.005), quinine (100 microM, P less than 0.005), or apamin (1 microM, P less than 0.005) prevented RVD. Inhibition of Cl- conductance with 9-anthracenecarboxylic acid (100 microM, P less than 0.005) or dipyridamole (75 microM, P less than 0.005) also prevented RVD. In isotonic HCO3(-)-buffered medium, the addition of gramicidin to cells generated conditions in which anion permeability was rate limiting for cell swelling. This swelling was inhibited 97% by 100 microM 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS). In K(+)-free, HCO3(-)-buffered medium containing DIDS and gramicidin hypotonic swelling resulted in continued (secondary) swelling (rel vol 1.19 +/- 0.01 vs. 1.25 +/- 0.02, P less than 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Activation of Cl-dependent K transport in Ehrlich ascites tumor cells

1986 ◽  
Vol 251 (3) ◽  
pp. C369-C379 ◽  
Author(s):  
B. Kramhoft ◽  
I. H. Lambert ◽  
E. K. Hoffmann ◽  
F. Jorgensen
Keyword(s):  
Regulatory Volume Decrease ◽  
Extracellular Ph ◽  
Cell Swelling ◽  
Disulfonic Acid ◽  
Cell Shrinkage ◽  
Ehrlich Cells ◽  
Ehrlich Ascites ◽  
Dependent Component ◽  
Ca Depletion ◽  
Volume Decrease

N-ethylmaleimide (NEM) treatment of steady-state Ehrlich cells induces a substantial net loss of cellular KCl and cell shrinkage. The majority of the initial K loss is Cl dependent. From estimates of membrane potential it is concluded that the NEM-induced KCl loss is electroneutral. The effect of NEM on H extrusion by cells in 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS)-containing medium showed that only an insignificant part of the K loss could be attributed to an activation of a K-H exchange system. Consequently, NEM appears to activate a K-Cl cotransport, which causes cell shrinkage. The anion preference of the K loss is Cl greater than Br much greater than SCN = NO3. NEM also seems to inhibit a Cl-dependent Na uptake previously described in shrunken cells. Addition of NEM to cells undergoing regulatory volume decrease after swelling in hyposmotic media results in a Cl-dependent acceleration of cell shrinkage, suggesting that a Cl-dependent component of K efflux is induced by NEM also in swollen cells. A Cl-dependent K efflux is also activated in Ca-depleted cells or at reduced extracellular pH after cell swelling. Under isotonic conditions activation of Cl-dependent K flux after Ca depletion or pH reduction could not be demonstrated. The combined results show that Ehrlich cells possess a latent K-Cl cotransport that becomes active after changes in the state of SH groups, regardless of the initial cell volume. A similar K-Cl cotransport is activated in hypotonically swollen cells after Ca depletion or after reduction of the extracellular pH.

Potentiation of regulatory volume decrease by P2U purinoceptors in HSG-PA cells

1996 ◽  
Vol 270 (1) ◽  
pp. C86-C97 ◽  
Author(s):  
H. D. Kim ◽  
J. W. Bowen ◽  
M. R. James-Kracke ◽  
L. A. Landon ◽  
J. M. Camden ◽  
...  
Keyword(s):  
Salivary Gland ◽  
Driving Force ◽  
Regulatory Volume Decrease ◽  
Cell Swelling ◽  
K Channels ◽  
Anion Conductance ◽  
Medium Osmolarity ◽  
Gland Duct ◽  
Underlying Mechanisms ◽  
Volume Decrease

HSG-PA human salivary gland duct cells exhibit progressively increased regulatory volume decrease (RVD) in response to decreased medium osmolarity. The P2U purinoceptor agonist UTP causes a potentiation of RVD, the extent of which is most pronounced in 220 mosM medium and is least apparent in 180 mosM medium. We examined the underlying mechanisms for this effect. Exposure of HSG-PA cells to UTP promotes Ca2+ mobilization, hyperpolarization, and net K+ efflux, suggesting the participation of Ca(2+)-activated K+ channels in RVD. To delineate the anion counterpart of K+ movement during RVD, cell swelling in the presence of gramicidin, which abolishes the membrane potential, was measured. In response to a sudden dilution in hypotonic media, gramicidin-treated cells swelled immediately, followed by a "secondary swelling" in 180 but not in 220 mosM medium. The results suggest that in 180 mosM cells perform spontaneous RVD mediated by increased anion conductance. In 220 mosM medium in which RVD is minimal, the increase in anion conductance is marginal. In our model of RVD in which cells were challenged by UTP, the ensuing hyperpolarization provides the driving force for net Cl- efflux, which is confirmed by tracer flux studies during purinoceptor-activated RVD. Thus RVD, which has long been regarded as a self-sufficient cellular program, appears to be subject to extracellular control in HSG-PA cells through receptor-mediated processes.

Volume-activated K+ and Cl- pathways of dissociated epithelial cells (MDCK): role of Ca2+

1990 ◽  
Vol 258 (5) ◽  
pp. C827-C834 ◽  
Author(s):  
A. Rothstein ◽  
E. Mack
Keyword(s):  
Mdck Cells ◽  
Regulatory Volume Decrease ◽  
Disulfonic Acid ◽  
Ionophore A23187 ◽  
Madin Darby Canine Kidney ◽  
Osmotic Swelling ◽  
Volume Activation ◽  
Darby Canine Kidney ◽  
Volume Decrease

Osmotic swelling of dissociated Madin-Darby canine kidney (MDCK) cells in NaCl medium is followed by shrinking (regulatory volume decrease, or RVD) or in KCl medium by secondary swelling. The cation ionophore gramicidin has little effect on volumes of isotonic cells but accelerates volume-activated changes in either medium. Immediately after hypotonic exposure, the membrane becomes transiently hyperpolarized followed by depolarization. The depolarization phase is diminished by the anion transport inhibitor 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS). Swelling is also associated with an almost immediate increase in Ca2+ influx and elevation of cytoplasmic Ca2+ ([Ca2+]i) preceding RVD. In Ca2(+)-free medium, [Ca2+]i rapidly declines to a low level. Osmotic swelling, under these circumstances, is associated with a small transient increase in [Ca2+]i, but RVD or secondary swelling (in KCl) are minimal. Under these conditions, addition of gramicidin or the Ca2(+)-ionophore A23187 induces significant volume changes, although not as large as those found in the presence of Ca2+. Quinine inhibits RVD in the absence of gramicidin, but not in its presence; oligomycin C, DIDS, and trifluoperazine, on the other hand, inhibit in the presence of the ionophore. These findings suggest that in MDCK cells RVD involves activation of distinct conductive K+ and Cl- pathways which allow escape of KCl and osmotically obligated water and that activation of both pathways is associated with elevated [Ca2+]i derived largely from volume activation of a Ca2(+)-influx pathway.

Resistance to osmotic lysis in BXD-31 mouse erythrocytes: association with upregulated K-Cl cotransport

1996 ◽  
Vol 270 (3) ◽  
pp. C866-C877 ◽  
Author(s):  
C. C. Armsby ◽  
A. K. Stuart-Tilley ◽  
S. L. Alper ◽  
C. Brugnara
Keyword(s):  
Normal Cell ◽  
Genetic Locus ◽  
Regulatory Volume Decrease ◽  
Osmotic Fragility ◽  
Cell Swelling ◽  
K Channel ◽  
Cell Dehydration ◽  
Osmotic Lysis ◽  
Volume Decrease ◽  
Characteristic Resistance

The decreased osmotic fragility and reduced K+ content of BXD-31 mouse erythrocytes arise from variation at a single genetic locus. We compared ion transport in erythrocytes from BXD-31 mice and the parental strain, DBA/2J. The strains had similar rates for Na-K pump, Na/H exchange, Na-K-2Cl cotransport, Ca2+ activated K+ channel, or AE1-mediated SO4 transport. In contrast, K-Cl cotransport was twice as active in BXD-31 as in DBA/2J cells. Cl- dependent K+ efflux from BXD-31 cells displayed steep activation by acid pH (with maximal transport occurring at pH 6.75), whereas DBA/2J erythrocytes displayed a far less dramatic response to pH. Both strains displayed regulatory volume decrease in response to cell swelling. However, a 62% greater loss of cell K+ via K-Cl cotransport was observed in the BXD-31 strain. Furthermore the decreased osmotic fragility of BXD-31 red blood cells was normalized by treatment with nystatin to achieve normal cell K+ and water content. Thus upregulated K-Cl cotransport induces cell dehydration and K+ deficit in BXD-31 erythrocytes and causes their characteristic resistance to osmotic lysis.

Mechanisms of regulatory volume decrease in UC-11MG human astrocytoma cells

1993 ◽  
Vol 264 (5) ◽  
pp. C1201-C1209 ◽  
Author(s):  
S. Medrano ◽  
E. Gruenstein
Keyword(s):  
Brain Injuries ◽  
Regulatory Volume Decrease ◽  
Transport Pathways ◽  
Astrocytoma Cells ◽  
Hypotonic Treatment ◽  
Human Astrocytoma ◽  
Stretch Activated Channels ◽  
Human Astrocytoma Cells ◽  
Volume Decrease

Swelling of astrocytes commonly occurs after cerebral ischemia and other brain injuries. Because these cells constitute 20-25% of human brain volume, their swelling is a major factor in the morbidity and mortality associated with cerebral edema. Many cells, including astrocytes, resist or reverse the tendency to swell by activating transport pathways that lead to a regulatory volume decrease. Here we report the results of studies designed to elucidate the mechanisms of the regulatory volume decrease that occurs after astrocytes are swollen by exposure to hypotonic medium. Using UC-11MG cells, a well-characterized, human, astrocytoma-derived line, we observed an increase in membrane permeability to both K+ and Cl- during regulatory volume decrease, consistent with a net loss of these ions. Neither the increase in K+ exit nor the regulatory volume decrease was affected by bumetanide, an inhibitor of anion-cation cotransport. On the other hand, the increased K+ efflux, as well as the regulatory volume decrease, was blocked by Gd3+, suggesting a putative role of stretch-activated cationic channels in the process of volume regulation. Although increases in intracellular free Ca2+ were also observed during hypotonic treatment, they occurred well after the onset of the regulatory volume decrease. Furthermore, the regulatory volume decrease was not affected by blocking the intracellular free Ca2+ increase with dimethyl 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid or by removal of extracellular Ca2+. These results indicate that the regulatory volume decrease in UC-11MG cells may involve stretch-activated channels that operate independently of changes in intracellular free Ca2+.

Control of intracellular pH during regulatory volume decrease in HL-60 cells

1994 ◽  
Vol 267 (4) ◽  
pp. C1057-C1066 ◽  
Author(s):  
K. R. Hallows ◽  
D. Restrepo ◽  
P. A. Knauf
Keyword(s):  
Intracellular Ph ◽  
Ph Regulation ◽  
Regulatory Volume Decrease ◽  
Transport Systems ◽  
Disulfonic Acid ◽  
Volume Dependence ◽  
Supportive Role ◽  
22Na Uptake ◽  
Volume Decrease ◽  
Stimulation Of

Intracellular pH (pHi) homeostasis was investigated in human promyelocytic leukemic HL-60 cells as they undergo regulatory volume decrease (RVD) in hypotonic media to determine how well pHi is regulated and which transport systems are involved. Cells suspended in hypotonic (50-60% of isotonic) media undergo a small (< 0.2 pH units), but significant (P < 0.05), intracellular acidification within 5 min. However, after 30 min of RVD, pHi is not significantly different from the initial pHi in 20 mM HCO3- medium and is significantly higher in HCO3(-)-free medium. Experiments performed in media with or without 150 microM 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid and HCO3- demonstrate that the anion exchanger (AE) mediates a net Cl- influx, with compensating HCO3- efflux, during RVD. To determine which transport systems are involved in counteracting this tendency toward acidification, we measured transport rates and examined the effect of transport system inhibitors on pHi. We found that inhibition of Na+/H+ exchange (NHE) with 12.5 microM ethylisoproplamiloride (EIPA) causes pHi to fall significantly by the end of 30 min of RVD. As assessed by EIPA-sensitive 22Na+ uptake measurements, NHE, largely dormant under resting isotonic conditions, becomes significantly activated by the end of 30 min of RVD, despite recovery of pHi and cell volume to near-normal levels. Thus a shift in the normal pHi dependence and/or volume dependence of NHE activity must occur during RVD under hypotonic conditions. In contrast, H(+)-monocarboxylate cotransport appears to play only a supportive role in pH regulation during RVD, as indicated by lack of stimulation of [14C]lactate efflux during RVD.

Physiological significance of hypotonicity-induced regulatory volume decrease: reduction in intracellular Cl− concentration acting as an intracellular signaling

2007 ◽  
Vol 292 (5) ◽  
pp. F1411-F1417 ◽  
Author(s):  
Hiroaki Miyazaki ◽  
Atsushi Shiozaki ◽  
Naomi Niisato ◽  
Yoshinori Marunaka
Keyword(s):  
Intracellular Signaling ◽  
Channel Blocker ◽  
Fluorescent Dyes ◽  
Regulatory Volume Decrease ◽  
Cell Swelling ◽  
Dependent Manner ◽  
Stimulatory Action ◽  
A6 Cells ◽  
Intracellular Signal ◽  
Volume Decrease

Regulatory volume decrease (RVD) occurs after hypotonicity-caused cell swelling. RVD is caused by activation of ion channels and transporters, which cause effluxes of K+, Cl−, and H2O, leading to cell shrinkage. Recently, we showed that hypotonicity stimulated transepithelial Na+ reabsorption via elevation of epithelial Na+ channel (α-ENaC) expression in renal epithelia A6 cells in an RVD-dependent manner and that reduction of intracellular Cl− concentration ([Cl−]i) stimulated the Na+ reabsorption. These suggest that RVD would reveal its stimulatory action on the Na+ reabsorption by reducing [Cl−]i. However, the reduction of [Cl−]i during RVD has not been definitely analyzed due to technical difficulties involved in halide-sensitive fluorescent dyes. In the present study, we developed a new method for the measurement of [Cl−]i change during RVD by using a high-resolution flow cytometer with a halide-specific fluorescent dye, N-(6-methoxyquinolyl) acetoethyl ester. The [Cl−]i in A6 cells in an isotonic medium was 43.6 ± 3.1 mM. After hypotonic shock (268 to 134 mosmol/kgH2O), a rapid increase of cell volume followed by RVD occurred. The RVD caused drastic diminution of [Cl−]i from 43.6 to 10.8 mM. Under an RVD-blocked condition with NPPB (Cl− channel blocker) or quinine (K+ channel blocker), we did not detect the reduction of [Cl−]i. Based on these observations, we conclude that one of the physiological significances of RVD is the reduction of [Cl−]i and that RVD shows its action via reduction of [Cl−]i acting as an intracellular signal regulating cellular physiological functions.

Hyposmotic activation of ICl,swell in rabbit nonpigmented ciliary epithelial cells involves increased ClC-3 trafficking to the plasma membrane

2004 ◽  
Vol 82 (6) ◽  
pp. 708-718 ◽  
Author(s):  
John P Vessey ◽  
Chanjuan Shi ◽  
Christine AB Jollimore ◽  
Kelly T Stevens ◽  
Miguel Coca-Prados ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Membrane Trafficking ◽  
Kinase Inhibitor ◽  
Regulatory Volume Decrease ◽  
Membrane Dynamics ◽  
Cell Swelling ◽  
Cl Channels ◽  
Phosphoinositide 3 Kinase ◽  
Nonpigmented Ciliary Epithelial ◽  
Volume Decrease

In mammalian nonpigmented ciliary epithelial (NPE) cells, hyposmotic stimulation leading to cell swelling activates an outwardly rectifying Cl– conductance (ICl,swell), which, in turn, results in regulatory volume decrease. The aim of this study was to determine whether increased trafficking of intracellular ClC-3 Cl channels to the plasma membrane could contribute to the ICl,swell following hyposmotic stimulation. Our results demonstrate that hyposmotic stimulation reversibly activates an outwardly rectifying Cl– current that is inhibited by phorbol-12-dibutyrate and niflumic acid. Transfection with ClC-3 antisense, but not sense, oligonucleotides reduced ClC-3 expression as well as ICl,swell. Intracellular dialysis with 2 different ClC-3 antibodies abolished activation of ICl,swell. Immunofluorescence microscopy showed that hyposmotic stimulation increased ClC-3 immunoreactivity at the plasma membrane. To determine whether this increased expression of ClC-3 at the plasma membrane could be due to increased vesicular trafficking, we examined membrane dynamics with the fluorescent membrane dye FM1-43. Hyposmotic stimulation rapidly increased the rate of exocytosis, which, along with ICl,swell, was inhibited by the phosphoinositide-3-kinase inhibitor wortmannin and the microtubule disrupting agent, nocodazole. These findings suggest that ClC-3 channels contribute to ICl,swell following hyposmotic stimulation through increased trafficking of channels to the plasma membrane.Key words: ClC-3, NPE, cell swelling, membrane trafficking, ciliary body epithelium.

Swelling-activated K+ transport via two functionally distinct pathways in eel erythrocytes

1996 ◽  
Vol 270 (1) ◽  
pp. R61-R70 ◽  
Author(s):  
J. D. Bursell ◽  
K. Kirk
Keyword(s):  
Regulatory Volume Decrease ◽  
Anguilla Anguilla ◽  
Cell Swelling ◽  
European Eel ◽  
Pharmacological Properties ◽  
Osmotic Swelling ◽  
Diverse Range ◽  
K Transport ◽  
Volume Decrease ◽  
In Cells

Following osmotic swelling, erythrocytes from the European eel, Anguilla anguilla, underwent a regulatory volume decrease. This was prevented by replacement of Na+ with K+ in the suspending medium, consistent with a role for the (normally outward) electrochemical K+ gradient in the volume-regulatory response. The effect of cell swelling on K- transport in these cells was investigated using 86Rb+ as a tracer for K+. Osmotic swelling resulted in an increase in ouabain-insensitive K+ transport that was highest for cells in Cl- and Br- media but which was also significant in I- and NO3- media. Treatment of eel erythrocytes suspended in isotonic Cl- or Br- (but not I- or NO3-) media with the sulfhydryl reagent N-ethylmaleimide (NEM) resulted in a large increase in K+ transport. A quantitative comparison of the pharmacological properties of the “Cl(-)-dependent” NEM-activated pathway with those of the “Cl(-)-independent” pathway mediating swelling-activated K+ transport in cells in Cl(-)-free (NO3- containing) media showed there to be significant differences between them. By contrast, the pharmacological properties of the Cl(-)-independent swelling-activated K+ pathway were indistinguishable from those of the pathway responsible for the swelling-activated transport of taurine, the major organic osmolyte in these cells. A pharmacological analysis of ouabain-insensitive K+ transport in cells swollen in a hypotonic Cl(-)-containing medium showed there to be two components, one with the characteristics of the NEM-activated system, the other showing the characteristics of the Cl(-)-independent swelling-activated pathway. The data are consistent with the presence of two functionally distinct swelling-activated K+ transport mechanisms in eel erythrocytes: a KCl cotransporter that is activated under isotonic conditions by NEM and a Cl(-)-independent, broad-specificity channel that accommodates a diverse range of organic and inorganic solutes.

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