Role of concentration and size of intracellular macromolecules in cell volume regulation

1997 ◽  
Vol 273 (2) ◽  
pp. C360-C370 ◽  
Author(s):  
J. C. Summers ◽  
L. Trais ◽  
R. Lajvardi ◽  
D. Hergan ◽  
R. Buechler ◽  
...  
Keyword(s):  
Cell Volume ◽  
Volume Regulation ◽  
Regulatory Volume Decrease ◽  
Cell Volume Regulation ◽  
Molecular Physiology ◽  
Average Molecular Mass ◽  
Membrane Stretch ◽  
Ca2 Channels ◽  
Volume Decrease

To gain insight into the mechanism(s) by which cells sense volume changes, specific predictions of the macromolecular crowding theory (A. P. Minton. In: Cellular and Molecular Physiology of Cell Volume Regulation, edited by K. Strange. Boca Raton, FL: CRC, 1994, p. 181-190. A. P. Minton, C. C. Colclasure, and J. C. Parker. Proc. Natl. Acad. Sci. USA 89: 10504-10506, 1992) were tested on the volume of internally perfused barnacle muscle cells. This preparation was chosen because it allows assessment of the effect on cell volume of changes in the intracellular macromolecular concentration and size while maintaining constant the ionic strength, membrane stretch, and osmolality. The predictions tested were that isotonic replacement of large macromolecules by smaller ones should induce volume decreases proportional to the initial macromolecular concentration and size as well as to the magnitude of the concentration reduction. The experimental results were consistent with these predictions: isotonic replacement of proteins or polymers with sucrose induced volume reductions, but this effect was only observed when the replacement was > or = 25% and the particular macromolecule had an average molecular mass of < or = 20 kDa and a concentration of at least 18 mg/ml. Volume reduction was effected by a mechanism identical with that of hypotonicity-induced regulatory volume decrease, namely, activation of verapamil-sensitive Ca2+ channels.

Regulation of cellular volume in rabbit ventricular myocytes: bumetanide, chlorothiazide, and ouabain

1991 ◽  
Vol 260 (1) ◽  
pp. C122-C131 ◽  
Author(s):  
K. Drewnowska ◽  
C. M. Baumgarten
Keyword(s):  
Cell Volume ◽  
Volume Regulation ◽  
Ventricular Myocytes ◽  
Regulatory Volume Decrease ◽  
Cell Volume Regulation ◽  
Volume Response ◽  
Rabbit Ventricular Myocytes ◽  
Cell Volumes ◽  
Measured Volume ◽  
Volume Decrease

Video microscopy was used to study the regulation of cell volume in isolated rabbit ventricular myocytes. Myocytes rapidly (less than or equal to 2 min) swelled and shrank in hyposmotic and hyperosmotic solutions, respectively, and this initial volume response was maintained without a regulatory volume decrease or increase for 20 min. Relative cell volumes (normalized to isosmotic solution, 1T) were as follows: 1.41 +/- 0.01 in 0.6T, 1.20 +/- 0.04 in 0.8T, 0.71 +/- 0.04 in 1.8T, and 0.57 +/- 0.03 in 2.6T. These volume changes were significantly less than expected if all of the measured volume was osmotically active water. Changes in width and thickness were significantly greater than changes in cell length. The idea that cotransport contributes to cell volume regulation was tested by inhibiting Na(+)-K(+)-2Cl- cotransport with bumetanide (BUM) and Na(+)-Cl- cotransport with chlorothiazide (CTZ). Under isotonic conditions, a 10-min exposure to BUM (1 microM), CTZ (100 microM), or BUM (10 microM) plus CTZ (100 microM) decreased relative cell volume to 0.87 +/- 0.01, 0.86 +/- 0.02, and 0.82 +/- 0.04, respectively. BUM plus CTZ also modified the response to osmotic stress. Swelling in 2.6T medium was 76% greater and shrinkage in 0.6T medium was 29% less than in the absence of diuretics. In contrast to the rapid effects of diuretics, inhibition of the Na(+)-K+ pump with 10 microM ouabain for 20 min did not affect cell volume in 1T solution. Nevertheless, ouabain decreased swelling in 0.6T medium by 52% and increased shrinkage in 1.8T medium by 34%. These data suggest that under isotonic conditions Na(+)-K(+)-2Cl- and Na(+)-Cl- cotransport are critical in establishing cell volume, but osmoregulation can compensate for Na(+)-K+ pump inhibition for at least 20 min. Under anisotonic conditions, the Na(+)-K+ pump and Na(+)-K(+)-2Cl- and/or Na(+)-Cl- cotransport are important in myocyte volume regulation.

Cell volume regulation by skate erythrocytes: role of potassium

1990 ◽  
Vol 258 (5) ◽  
pp. R1217-R1223 ◽  
Author(s):  
K. G. Dickman ◽  
L. Goldstein
Keyword(s):  
Cell Volume ◽  
Phorbol Ester ◽  
Volume Regulation ◽  
Regulatory Volume Decrease ◽  
Cell Volume Regulation ◽  
Disulfonic Acid ◽  
Ionophore A23187 ◽  
K Uptake ◽  
K Transport

The role of K transport during cell volume regulation in response to extracellular osmolality, protein kinase C activation, and cellular Ca was examined in skate (Raja erinacea) red blood cells (RBC). Reduction of medium osmolality from 960 to 660 mosmol/kgH2O had no effect on K uptake or efflux despite a 25% increase in cell volume. Further reduction to 460 mosmol/kgH2O caused K uptake to double and K efflux to triple resulting in net K loss. Net K efflux in 460 mosmol/kgH2O medium was correlated with the presence of a regulatory volume decrease, which was sensitive to the anion transport inhibitor 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) and insensitive to chloride replacement. K-K exchange was absent in both isotonic and hypotonic media. Treatment with the Ca ionophore A23187 in the presence of Ca had no effect on either cell volume or K efflux in isotonic medium, indicating the absence of Ca-activated K transport. In contrast, phorbol ester treatment caused cell volume, Na content, and proton and K efflux to increase. Consistent with activation of Na-H exchange, phorbol ester effects were inhibited by dimethylamiloride. This study constitutes the first demonstration of volume-sensitive K transport in RBC from the most primitive vertebrate studied to date.

scholarly journals Role of TASK2 Potassium Channels Regarding Volume Regulation in Primary Cultures of Mouse Proximal Tubules

2003 ◽  
Vol 122 (2) ◽  
pp. 177-190 ◽  
Author(s):  
Herve Barriere ◽  
Radia Belfodil ◽  
Isabelle Rubera ◽  
Michel Tauc ◽  
Florian Lesage ◽  
...  
Keyword(s):  
Cell Volume ◽  
Volume Regulation ◽  
Primary Cultures ◽  
Regulatory Volume Decrease ◽  
Cell Volume Regulation ◽  
Proximal Tubules ◽  
Wild Type ◽  
Convoluted Tubules ◽  
K Currents

Several papers reported the role of TASK2 channels in cell volume regulation and regulatory volume decrease (RVD). To check the possibility that the TASK2 channel modulates the RVD process in kidney, we performed primary cultures of proximal convoluted tubules (PCT) and distal convoluted tubules (DCT) from wild-type and TASK2 knockout (KO) mice. In KO mice, the TASK2 coding sequence was in part replaced by the lac-Z gene. This allows for the precise localization of TASK2 in kidney sections using β-galactosidase staining. TASK2 was only localized in PCT cells. K+ currents were analyzed by the whole-cell clamp technique with 125 mM K-gluconate in the pipette and 140 mM Na-gluconate in the bath. In PCT cells from wild-type mice, hypotonicity induced swelling-activated K+ currents insensitive to 1 mM tetraethylammonium, 10 nM charybdotoxin, and 10 μM 293B, but blocked by 500 μM quinidine and 10 μM clofilium. These currents were increased in alkaline pH and decreased in acidic pH. In PCT cells from TASK2 KO, swelling-activated K+ currents were completely impaired. In conclusion, the TASK2 channel is expressed in kidney proximal cells and could be the swelling-activated K+ channel responsible for the cell volume regulation process during osmolyte absorptions in the proximal tubules.

Cation transport in mouse erythrocytes: role of K(+)-Cl- cotransport in regulatory volume decrease

1995 ◽  
Vol 268 (4) ◽  
pp. C894-C902 ◽  
Author(s):  
C. C. Armsby ◽  
C. Brugnara ◽  
S. L. Alper
Keyword(s):  
Volume Regulation ◽  
Inhibitory Concentration ◽  
Inbred Mouse ◽  
Regulatory Volume Decrease ◽  
Cell Volume Regulation ◽  
Cation Transport ◽  
Hypotonic Medium ◽  
Hypotonic Swelling ◽  
Volume Decrease

We investigated cation transport and cell volume regulation in erythrocytes of CD1 and C57/B6 mice. Swelling of cells from either strain stimulated K+ efflux that was insensitive to ouabain, bumetanide, and clotrimazole. Seventy-five percent of swelling-induced K+ efflux was Cl- dependent (inhibited by sulfamate or methanesulfonate, partially by NO3-, but not by SCN-) and was inhibited by okadaic acid (OA; 50% inhibitory concentration = 18 +/- 6 nM in CD1 and 10 +/- 4 nM in C57/B6). In both strains, K+ efflux into isotonic medium was stimulated by staurosporine or by N-ethylmaleimide, and the latter was partially blocked by pretreatment of cells with OA. When cells of either strain were incubated in hypotonic medium or preswollen isosmotically with nystatin, OA-sensitive regulatory volume decrease (RVD) and K+ loss were observed. RVD produced by hypotonic swelling was prevented by Cl- replacement with sulfamate or methanesulfonate. These properties suggest the presence in outbred and inbred mouse erythrocytes of RVD mediated by K(+)-Cl- cotransport.

Cell volume regulation in rabbit proximal straight tubule perfused in vitro

1987 ◽  
Vol 252 (5) ◽  
pp. F922-F932 ◽  
Author(s):  
K. L. Kirk ◽  
J. A. Schafer ◽  
D. R. DiBona
Keyword(s):  
Cell Volume ◽  
Volume Regulation ◽  
Time Course ◽  
Regulatory Volume Decrease ◽  
Cell Volume Regulation ◽  
Physiological Role ◽  
Cell Swelling ◽  
Computer Based

Volume regulation in the perfused proximal nephron of the rabbit was examined quantitatively with a computer-based method for estimating cell volume from differential interference-contrast microscopic images of isolated nephron segments. Following a hyperosmotic challenge (290-390 mosmol), the cells shrank as simple osmometers without a subsequent regulatory volume increase. Conversely, cell swelling induced by a hyposmotic challenge (290-190 mosmol) was completely reversed with a triphasic time course in which a rapid (less than 2 min) initial volume decline was followed by secondary swelling and shrinking phases. A similar regulatory volume decrease was observed following isosmotic cell swelling that was induced by exposure to 290 mosmol, urea-containing solutions. In addition, the cells partially reversed isosmotic swelling that was induced by the luminal replacement of a relatively impermeant cation (i.e., choline) with Na+ and a concomitant increase in luminal solute entry. Our results support two conclusions. First, there exist quantitative differences between the volume regulatory behaviors of perfused and nonperfused proximal tubules, the latter of which exhibit an incomplete and monotonic reversal of hyposmotic cell swelling (M. Dellasega and J. Grantham, Am. J. Physiol. 224: 1288-1294, 1973). Second, the primary physiological role of cell volume regulation in the proximal nephron may be to minimize isosmotic cell swelling associated with acute imbalances in the rates of cell solute entry and exit.

Fundamental role of ClC-3 in volume-sensitive Cl- channel function and cell volume regulation in AGS cells

2003 ◽  
Vol 285 (5) ◽  
pp. G938-G948 ◽  
Author(s):  
Nan Ge Jin ◽  
Jin Kyoung Kim ◽  
Dong Ki Yang ◽  
Soo Jin Cho ◽  
Jung Mogg Kim ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Cell Volume ◽  
Volume Regulation ◽  
Regulatory Volume Decrease ◽  
Cell Volume Regulation ◽  
Reversal Potential ◽  
Hypotonic Solution ◽  
Gastric Epithelial Cells ◽  
Ags Cells

Volume regulation is essential for cell function, but it is unknown which channels are involved in a regulatory volume decrease (RVD) in human gastric epithelial cells. Exposure to a hypotonic solution caused the increase in AGS cell volume, followed by the activation of a current. The reversal potential of the swelling-induced current suggested that Cl- was the primary charge carrier. The selectivity sequence for different anions was I- > Br- > Cl- > F- > gluconate. This current was inhibited by flufenamate, DIDS, tamoxifen, and 5-nitro-2-(3-phenylpropylamino)benzoate. Intracellular dialysis of three different anti-ClC-3 antibodies abolished or attenuated the Cl- current and disrupted RVD, whereas the current and RVD was unaltered by anti-ClC-2 antibody. Immunoblot studies demonstrated the presence of ClC-3 protein in Hela and AGS cells. RT-PCR analysis detected expression of ClC-3, MDR-1, and pICln mRNA in AGS cells. These results suggest a fundamental role of endogenous ClC-3 in the swelling-activated Cl- channels function and cell volume regulation in human gastric epithelial cells.

On the role of TRPC1 in control of Ca2+ influx, cell volume, and cell cycle

2012 ◽  
Vol 303 (6) ◽  
pp. C625-C634 ◽  
Author(s):  
C. P. Madsen ◽  
T. K. Klausen ◽  
A. Fabian ◽  
B. J. Hansen ◽  
S. F. Pedersen ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Cell Volume ◽  
Volume Regulation ◽  
Cell Cycle Progression ◽  
Regulatory Volume Decrease ◽  
Cell Volume Regulation ◽  
S Phase ◽  
Cycle Progression

Ca+ signaling plays a crucial role in control of cell cycle progression, but the understanding of the dynamics of Ca2+ influx and release of Ca2+ from intracellular stores during the cell cycle is far from complete. The aim of the present study was to investigate the role of the free extracellular Ca2+ concentration ([Ca2+]o) in cell proliferation, the pattern of changes in the free intracellular Ca2+ concentration ([Ca2+]i) during cell cycle progression, and the role of the transient receptor potential (TRP)C1 in these changes as well as in cell cycle progression and cell volume regulation. In Ehrlich Lettré Ascites (ELA) cells, [Ca2+]i decreased significantly, and the thapsigargin-releasable Ca2+ pool in the intracellular stores increased in G1 as compared with G0. Store-depletion-operated Ca2+ entry (SOCE) and TRPC1 protein expression level were both higher in G1 than in G0 and S phase, in parallel with a more effective volume regulation after swelling [regulatory volume decrease (RVD)] in G1 as compared with S phase. Furthermore, reduction of [Ca2+]o, as well as two unspecific SOCE inhibitors, 2-APB (2-aminoethyldiphenyl borinate) and SKF96365 (1-(β-[3-(4-methoxy-phenyl)propoxyl-4-methoxyphenethyl)1H-imidazole-hydrochloride), inhibited ELA cell proliferation. Finally, Madin-Darby canine kidney cells in which TRPC1 was stably silenced [TRPC1 knockdown (TRPC1-KD) MDCK] exhibited reduced SOCE, slower RVD, and reduced cell proliferation compared with mock controls. In conclusion, in ELA cells, SOCE and TRPC1 both seem to be upregulated in G1 as compared with S phase, concomitant with an increased rate of RVD. Furthermore, TRPC1-KD MDCK cells exhibit decreased SOCE, decreased RVD, and decreased proliferation, suggesting that, at least in certain cell types, TRPC1 is regulated during cell cycle progression and is involved in SOCE, RVD, and cell proliferation.

TRPM7 is a stretch- and swelling-activated cation channel involved in volume regulation in human epithelial cells

2007 ◽  
Vol 292 (1) ◽  
pp. C460-C467 ◽  
Author(s):  
Tomohiro Numata ◽  
Takahiro Shimizu ◽  
Yasunobu Okada
Keyword(s):  
Cell Volume ◽  
Hela Cells ◽  
Volume Regulation ◽  
Transient Receptor Potential ◽  
Regulatory Volume Decrease ◽  
Cell Volume Regulation ◽  
Cation Channel ◽  
Cell Swelling ◽  
Whole Cell ◽  
Membrane Stretch

Stretch- and swelling-activated cation (SSAC) channels play essential roles not only in sensing and transducing external mechanical stresses but also in regulating cell volume in living cells. However, the molecular nature of the SSAC channel has not been clarified. In human epithelial HeLa cells, single-channel recordings in cell-attached and inside-out patches revealed expression of a Mg2+- and Gd3+-sensitive nonselective cation channel that is exquisitely sensitive to membrane stretch. Whole cell recordings revealed that the macroscopic cationic currents exhibit transient receptor potential (TRP) melastatin (TRPM)7-like properties such as outward rectification and sensitivity to Mg2+ and Gd3+. The whole cell cation current was augmented by osmotic cell swelling. RT-PCR and Western blotting demonstrated molecular expression of TRPM7 in HeLa cells. Treatment with small interfering RNA (siRNA) targeted against TRPM7 led to abolition of single stretch-activated cation channel currents and of swelling-activated, whole cell cation currents in HeLa cells. The silencing of TRPM7 by siRNA reduced the rate of cell volume recovery after osmotic swelling. A similar inhibition of regulatory volume decrease was also observed when extracellular Ca2+ was removed or Gd3+ was applied. It is thus concluded that TRPM7 represents the SSAC channel endogenously expressed in HeLa cells and that, by serving as a swelling-induced Ca2+ influx pathway, it plays an important role in cell volume regulation.

Activation of voltage-gated Na+ and Ca2+ channels is required for glutamate release from retinal glial cells implicated in cell volume regulation

Neuroscience ◽  
2011 ◽  
Vol 188 ◽  
pp. 23-34 ◽  
Author(s):  
R. Linnertz ◽  
A. Wurm ◽  
T. Pannicke ◽  
K. Krügel ◽  
M. Hollborn ◽  
...  
Keyword(s):  
Cell Volume ◽  
Glial Cells ◽  
Volume Regulation ◽  
Glutamate Release ◽  
Cell Volume Regulation ◽  
Voltage Gated ◽  
Ca2 Channels

scholarly journals Human trabecular meshwork cell volume regulation

2002 ◽  
Vol 283 (1) ◽  
pp. C315-C326 ◽  
Author(s):  
Claire H. Mitchell ◽  
Johannes C. Fleischhauer ◽  
W. Daniel Stamer ◽  
K. Peterson-Yantorno ◽  
Mortimer M. Civan
Keyword(s):  
Cell Volume ◽  
Trabecular Meshwork ◽  
Regulatory Volume Decrease ◽  
Cell Volume Regulation ◽  
Channel Blockers ◽  
Uptake Mechanism ◽  
Fluid Uptake ◽  
Intracellular Ca ◽  
Predominant Effect ◽  
Volume Decrease

The volume of certain subpopulations of trabecular meshwork (TM) cells may modify outflow resistance of aqueous humor, thereby altering intraocular pressure. This study examines the contribution that Na+/H+, Cl−/HCO[Formula: see text]exchange, and K+-Cl− efflux mechanisms have on the volume of TM cells. Volume, Cl− currents, and intracellular Ca2+ activity of cultured human TM cells were studied with calcein fluorescence, whole cell patch clamping, and fura 2 fluorescence, respectively. At physiological bicarbonate concentration, the selective Na+/H+ antiport inhibitor dimethylamiloride reduced isotonic cell volume. Hypotonicity triggered a regulatory volume decrease (RVD), which could be inhibited by the Cl− channel blocker 5-nitro-2-(3-phenylpropylamino)-benzoate (NPPB), the K+channel blockers Ba2+ and tetraethylammonium, and the K+-Cl− symport blocker [(dihydroindenyl)oxy]alkanoic acid. The fluid uptake mechanism in isotonic conditions was dependent on bicarbonate; at physiological levels, the Na+/H+ exchange inhibitor dimethylamiloride reduced cell volume, whereas at low levels the Na+-K+-2Cl− symport inhibitor bumetanide had the predominant effect. Patch-clamp measurements showed that hypotonicity activated an outwardly rectifying, NPPB-sensitive Cl− channel displaying the permeability ranking Cl− > methylsulfonate > aspartate. 2,3-Butanedione 2-monoxime antagonized actomyosin activity and both increased baseline [Ca2+] and abolished swelling-activated increase in [Ca2+], but it did not affect RVD. Results indicate that human TM cells display a Ca2+-independent RVD and that volume is regulated by swelling-activated K+ and Cl− channels, Na+/H+ antiports, and possibly K+-Cl− symports in addition to Na+-K+-2Cl− symports.

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