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.

scholarly journals Substrate Stiffness-Dependent Regulatory Volume Decrease and Calcium Signaling in Chondrocytes

2020 ◽  
Author(s):  
Quanyou Zhang ◽  
Min Zhang ◽  
Xiaoan Wu ◽  
Genlai Du ◽  
Xiaochun Wei ◽  
...  
Keyword(s):  
Calcium Signaling ◽  
Structural Changes ◽  
Regulatory Volume Decrease ◽  
Substrate Stiffness ◽  
Cell Swelling ◽  
Dependent Manner ◽  
Soft Substrate ◽  
Dynamical Deformation ◽  
Osmotic Challenge ◽  
Volume Decrease

Abstract The pericellular matrix stiffness is strongly associated with its biochemical and structural changes During the aging and osteoarthritis progresses of articular cartilage. However, how substrate stiffness modulates the chondrocyte regulatory volume decrease (RVD) and calcium signaling remains unknown. This study aims to investigate the effects of substrate stiffness on the chondrocyte RVD and calcium signaling by recapitulating the physiologically relevant substrate stiffness. Our results showed that substrate stiffness induced completely different dynamical deformation between the cell swelling and recovering progresses. Chondrocytes swelled faster on the soft substrate but recovered slower than the stiff substrate during the RVD response induced by the hypo-osmotic challenge. We found that stiff substrate enhanced the cytosolic Ca2+ oscillation of chondrocytes in the iso-osmotic medium. More importantly, chondrocytes exhibited a distinctive cytosolic Ca2+ oscillation during the RVD response. Soft substrate significantly improved the Ca2+ oscillation during the cell swelling whereas stiff substrate enhanced the cytosolic Ca2+ oscillation during the cell recovering. Our work also suggests that TRPV4 channel are involved in the chondrocyte sensing substrate stiffness and RVD response by mediating Ca2+ signaling in a stiffness-dependent manner. It helps to understand a previously unidentified relationship between substrate stiffness and RVD response under the hypo-osmotic challenge.

Dihydropyridine-sensitive cell volume regulation in proximal tubule: the calcium window

1990 ◽  
Vol 259 (6) ◽  
pp. F950-F960 ◽  
Author(s):  
N. A. McCarty ◽  
R. G. O'Neil
Keyword(s):  
Cell Volume ◽  
Volume Regulation ◽  
Regulatory Volume Decrease ◽  
Cell Volume Regulation ◽  
Cell Swelling ◽  
Channel Blockers ◽  
Ca Channel ◽  
Hypotonic Solution ◽  
Dependent Manner ◽  
Intracellular Ca

The mechanism underlying the activation of hypotonic cell volume regulation was studied in rabbit proximal straight tubule (PST). When isolated non-perfused tubules were exposed to hypotonic solution, cells swelled rapidly and then underwent a regulatory volume decrease (RVD). The extent of regulation after swelling was highly dependent on extracellular Ca concentration ([Ca2+]o), with a half-maximal inhibition (K1/2) for [Ca2+]o of approximately 100 microM. RVD was blocked by the Ca-channel blockers verapamil, lanthanum, and the dihydropyridines (DHP) nifedipine and nitrendipine, implicating voltage-activated Ca channels in the RVD response. Using the fura-2 fluorescence-ratio technique, we observed that cell swelling caused a sustained rise in intracellular Ca ([Ca2+]i) only when [Ca2+]o was normal (1 mM) but not when [Ca2+]o was low (1-10 microM). Furthermore, external Ca was required early on during swelling to induce RVD. If RVD was initially blocked by reducing [Ca2+]o or by addition of verapamil during hypotonic swelling, volume regulation could only be restored by subsequently inducing Ca entry within the first 1 min or less of exposure to hypotonic solution. These data indicate a "calcium window" of less than 1 min, during which RVD is sensitive to Ca, and that part of the Ca-dependent mechanism responsible for achieving RVD undergoes inactivation after swelling. It is concluded that RVD in rabbit PST is modulated by Ca via a DHP-sensitive mechanism in a time-dependent manner.

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.

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.

Association of intrinsic pICln with volume-activated Cl− current and volume regulation in a native epithelial cell

1999 ◽  
Vol 276 (1) ◽  
pp. C182-C192 ◽  
Author(s):  
Lixin Chen ◽  
Liwei Wang ◽  
Tim J. C. Jacob
Keyword(s):  
Antisense Oligonucleotides ◽  
Volume Regulation ◽  
Regulatory Volume Decrease ◽  
Hypotonic Solution ◽  
Dependent Manner ◽  
Nonpigmented Ciliary Epithelial ◽  
The Relationship ◽  
Dose Dependent ◽  
Hypotonic Swelling ◽  
Volume Decrease

We investigated the relationship between pICln, the volume-activated Cl−current, and volume regulation in native bovine nonpigmented ciliary epithelial (NPCE) cells. Immunofluorescence studies demonstrated the presence of pICln protein in the NPCE cells. Exposure to hypotonic solution activated a Cl− current and induced regulatory volume decrease (RVD) in freshly isolated bovine NPCE cells. Three antisense oligonucleotides complementary to human pICln mRNA were used in the experiments. The antisense oligonucleotides were taken up by the cells in a dose-dependent manner. The antisense oligonucleotides, designed to be complementary to the initiation codon region of the human pICln mRNA, “knocked down” the pICln protein immunofluorescence, delayed the activation of volume-activated Cl− current, diminished the value of the current, and reduced the ability of the cells to volume regulate. We conclude that pIClnis involved in the activation pathway of the volume-activated Cl− current and RVD following hypotonic swelling.

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.

Mature Sickle and Normal Red Cells Exhibit Regulatory Volume Decrease Activated by Urea and Mediated by KCl Cotransport.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 2321-2321
Author(s):  
Clinton H. Joiner ◽  
R. Kirk Rettig ◽  
Mary Palascak ◽  
Amher Sheriff ◽  
Robert M. Cohen ◽  
...  
Keyword(s):  
Steady State ◽  
Relative Size ◽  
Regulatory Volume Decrease ◽  
Hemoglobin Concentration ◽  
Progressive Increase ◽  
Cell Swelling ◽  
Frequency Distributions ◽  
Kcl Cotransport ◽  
Volume Decrease

Abstract KCl Cotransport (KCC) is active in normal (AA) reticulocytes and overly active in sickle (SS) reticulocytes. Cell swelling activates KCC and induces a powerful regulatory volume decrease (RVD) in reticulocytes, which increases cellular hemoglobin concentration (CHC) to new steady state values that are higher in SS than AA cells (Blood2004;104(9):2954–60). We recently showed that urea (300–900 mM), which strongly activates KCC, also induces an intense RVD with even higher final CHC values (SS>AA) (Blood2004; 104 (11): 976a). Because KCC activity is high in reticulocyte-rich samples in both SS and AA blood, KCC activity has been assumed to be minimal in mature cells. We now report that mature RBC exhibit RVD stimulated by urea and mediated by KCC. AA and SS RBC were washed in HBS and treated with nystatin to increase cation content and decrease CHC to 22–24 gm/dl. During incubation at 37o in HBS (145 mM NaCl, 5 KCl, 1 MgCl2, 10 glucose, 20 HEPES, pH 7.4) ± 600 mM urea, timed samples were taken into iced HBS, washed, and kept on ice until analyzed later that day on an Advia 120 automated cell counter, which reports frequency distributions for CHC of both mature RBC and reticulocytes. As previously reported, within 30 min reticulocytes achieved a new steady state CHC which was higher for SS than AA cells, though the speed of RVD was similar. Surprisingly, mean CHC of mature (non-reticulocyte) RBC in both AA and SS blood also increased upon incubation with urea. RVD in mature cells was slower than in reticulocytes and was apparently incomplete after 2 hours. RVD in mature RBC was completely abrogated (CHC was stable) in the absence of Cl- (sulfamate substitution) or in the presence of 100 uM DIOA (dihydro-indenyl-oxy-alkanoic acid), both of which inhibit KCC activity. Whereas reticulocyte CHC frequency distributions after urea-stimulated KCC-mediated RVD showed a single population, CHC distributions for mature RBC revealed two distinct sub-populations: One in which CHC changed little during incubation and a second which achieved a CHC similar to that achieved by reticulocytes after RVD. The relative size of the volume regulating (high CHC) sub-population increased steadily throughout the incubation, which was responsible for the progressive increase in mean CHC values. The high CHC sub-population was not apparent when cells were incubated in Cl- free media or with DIOA, indicating that RVD was mediated by KCC. After 2 hours incubation, 67 ± 8 % of SS RBC had shifted to higher CHC, compared to 37 ± 11 % of mature AA RBC (p<<0.001 by t-test). The progressive change in CHC histograms during incubation was consistent with cells achieving the same final CHC values at various rates. In preliminary studies with biotin-labeled AA cells ageing in vivo, urea-stimulated RVD in mature cells diminished with time, but persisted through most of RBC lifespan. These data indicate that the KCl cotransporter remains in the membrane of mature AA RBC, and is capable of producing RVD under the strong stimulation of urea. In SS RBC, which have shorter lifespan, a majority of non-reticulocytes retain urea-stimulated KCC activity.

Swelling-activated K fluxes in vascular endothelial cells: volume regulation via K-Cl cotransport and K channels

1993 ◽  
Vol 265 (3) ◽  
pp. C763-C769 ◽  
Author(s):  
P. B. Perry ◽  
W. C. O'Neill
Keyword(s):  
Endothelial Cells ◽  
Vascular Endothelial Cells ◽  
Regulatory Volume Decrease ◽  
Cell Swelling ◽  
Ionophore A23187 ◽  
Vascular Endothelial ◽  
Aortic Endothelial Cells ◽  
K Channels ◽  
Volume Decrease ◽  
Aortic Endothelial

K efflux pathways responsible for regulatory volume decrease (RVD) were examined in bovine aortic endothelial cells. Hypotonic swelling produced a rapid and reversible threefold increase in bumetanide-insensitive 86Rb efflux. Swelling-activated 86Rb efflux was inhibited 43% when Cl was replaced with NO3, and this Cl-dependent efflux was inhibited by 1 mM furosemide. Neither Cl replacement nor furosemide inhibited the efflux stimulated by a Ca ionophore (A23187) in isotonic medium. Swelling-activated 86Rb efflux was also inhibited by 4,4'-diisothiocyanostilbene-2,2'-disulfonate but not by dinitrostilbenedisulfonate. Cell swelling induced a volume-regulatory K loss that was incomplete in hypotonic medium but complete and more rapid when bumetanide was added or when cells were swollen isosmotically. K loss in the presence of bumetanide was partially blocked by furosemide. We conclude that two separate swelling-activated K fluxes mediate RVD in aortic endothelial cells: a Cl-dependent, furosemide-sensitive, but bumetanide-insensitive flux that is consistent with K-Cl cotransport, and a Cl-independent efflux that presumably is mediated by K channels.

scholarly journals Cell Volume Regulation in the Epidermis

2021 ◽  
Vol 55 (S1) ◽  
pp. 57-70
Keyword(s):  
Cell Volume ◽  
Current Knowledge ◽  
Regulatory Volume Decrease ◽  
Cell Volume Regulation ◽  
Skin Layer ◽  
Cell Swelling ◽  
Volume Changes ◽  
Barrier Formation ◽  
Molecular Machinery ◽  
Volume Decrease

In order to cope with external stressors such as changes in humidity and temperature or irritating substances, the epidermis as the outermost skin layer forms a continuously renewing and ideally intact protective barrier. Under certain circumstances, this barrier can be impaired and epidermal cells have to counteract cell swelling or shrinkage induced by osmotic stress via regulatory volume decrease (RVD) or increase (RVI). Here, we will review the current knowledge regarding the molecular machinery underlying RVD and RVI in the epidermis. Furthermore, we will discuss the current understanding how cell volume changes and its regulators are associated with epidermal renewal and barrier formation.

Sign in / Sign up

Export Citation Format

Share Document