Cerebral Edema, Cell Volume Regulation, and the Role of Ion Channels in Organic Osmolyte Transport

1997 ◽  
Vol 27 (6) ◽  
pp. 279-285 ◽  
Author(s):  
Paul S. Jackson ◽  
Joseph Madsen
Keyword(s):  
Ion Channels ◽  
Cell Volume ◽  
Cerebral Edema ◽  
Volume Regulation ◽  
Cell Volume Regulation ◽  
Organic Osmolyte ◽  
Osmolyte Transport

scholarly journals Hydrogen, Bicarbonate, and Their Associated Exchangers in Cell Volume Regulation

2021 ◽  
Vol 9 ◽  
Author(s):  
Yizeng Li ◽  
Xiaohan Zhou ◽  
Sean X. Sun
Keyword(s):  
Ion Channels ◽  
Cell Volume ◽  
Volume Regulation ◽  
Mammalian Cells ◽  
Molecular Mechanisms ◽  
Cell Function ◽  
Water Flux ◽  
Cell Volume Regulation ◽  
Sodium Potassium ◽  
Before And After

Cells lacking a stiff cell wall, e.g., mammalian cells, must actively regulate their volume to maintain proper cell function. On the time scale that protein production is negligible, water flow in and out of the cell determines the cell volume variation. Water flux follows hydraulic and osmotic gradients; the latter is generated by various ion channels, transporters, and pumps in the cell membrane. Compared to the widely studied roles of sodium, potassium, and chloride in cell volume regulation, the effects of proton and bicarbonate are less understood. In this work, we use mathematical models to analyze how proton and bicarbonate, combined with sodium, potassium, chloride, and buffer species, regulate cell volume upon inhibition of ion channels, transporters, and pumps. The model includes several common, widely expressed ion transporters and focuses on obtaining generic outcomes. Results show that the intracellular osmolarity remains almost constant before and after cell volume change. The steady-state cell volume does not depend on water permeability. In addition, to ensure the stability of cell volume and ion concentrations, cells need to develop redundant mechanisms to maintain homeostasis, i.e., multiple ion channels or transporters are involved in the flux of the same ion species. These results provide insights for molecular mechanisms of cell volume regulation with additional implications for water-driven cell migration.

Modeling cell volume regulation in nonexcitable cells: the roles of the Na+ pump and of cotransport systems

1998 ◽  
Vol 275 (4) ◽  
pp. C1067-C1080 ◽  
Author(s):  
Julio A. Hernández ◽  
Ernesto Cristina
Keyword(s):  
Cell Volume ◽  
Volume Regulation ◽  
Present Model ◽  
Animal Cell ◽  
Cell Volume Regulation ◽  
Kinetic Scheme ◽  
Short Term ◽  
Rates Of Change

The purpose of this study is to contribute to understanding the role of Na+-K+-ATPase and of ionic cotransporters in the regulation of cell volume, by employing a model that describes the rates of change of the intracellular concentrations of Na+, K+, and Cl−, of the cell volume, and of the membrane potential. In most previous models of dynamic cellular phenomena, Na+-K+-ATPase is incorporated via phenomenological formulations; the enzyme is incorporated here via an explicit kinetic scheme. Another feature of the present model is the capability to perform short-term cell volume regulation mediated by cotransporters of KCl and NaCl. The model is employed to perform numerical simulations for a “typical” nonpolarized animal cell. Basically, the results are consistent with the view that the Na+ pump mainly plays a long-term role in the maintenance of the electrochemical gradients of Na+ and K+ and that short-term cell volume regulation is achieved via passive transport, exemplified in this case by the cotransport of KCl and NaCl.

Ion Channels and Cell Volume Regulation: Chaos in an Organized System

Physiology ◽  
1990 ◽  
Vol 5 (3) ◽  
pp. 112-119 ◽  
Author(s):  
SA Lewis ◽  
P Donaldson
Keyword(s):  
Ion Channels ◽  
Cell Volume ◽  
Volume Regulation ◽  
Cell Volume Regulation ◽  
Cell Types ◽  
Initial Increase ◽  
Normal Value ◽  
Basic Strategy

Exposure of many vertebrate cells to solutions more dilute or concentrated than the physiological "norm" results in an initial increase or decrease in cell volume followed by a recovery of volume toward a normal value. Although the basic strategy for volume regulation is the same for cell types studied, the mechanism by which the cell regulates ion channels appears to be tissue dependent.

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.

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.

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.

scholarly journals Cell volume regulation: the role of taurine loss in maintaining membrane potential and cell pH

2000 ◽  
Vol 523 (1) ◽  
pp. 147-154 ◽  
Author(s):  
H. Guizouarn ◽  
R. Motais ◽  
F. Garcia‐Romeu ◽  
F. Borgese
Keyword(s):  
Membrane Potential ◽  
Cell Volume ◽  
Volume Regulation ◽  
Cell Volume Regulation ◽  
Cell Ph

Role of Na-K-Cl cotransport in vascular endothelial cell volume regulation

1993 ◽  
Vol 264 (5) ◽  
pp. C1316-C1326 ◽  
Author(s):  
M. E. O'Donnell
Keyword(s):  
Endothelial Cells ◽  
Endothelial Cell ◽  
Cell Volume ◽  
Volume Regulation ◽  
Cell Volume Regulation ◽  
Vascular Endothelial ◽  
Cerebral Microvessels ◽  
Hypertonic Medium ◽  
Endothelial Cell Function

Vascular endothelial cells have been shown previously to possess a highly active Na-K-Cl cotransport system that mediates the major portion of total K influx and is regulated by a variety of vasoactive hormones and neurotransmitters. These observations suggest that the cotransporter may be an important component of endothelial cell function. The present study was conducted to investigate the role of Na-K-Cl cotransport in regulation of endothelial cell volume. Cultured bovine aortic endothelial cells were exposed to media of varying tonicities and Na-K-Cl cotransport activity assessed as bumetanide-sensitive K influx. Increasing the extracellular tonicity by increments as small as 10 mosM was found to cause significant stimulation of cotransport activity, and lowering tonicity reduced activity of the transporter. Exposure of endothelial cells to hypertonic medium was also found to increase bumetanide-sensitive net uptake of Na and K and total cellular Na and K content. Endothelial cell volume was evaluated by [14C]urea determination of intracellular water space in endothelial monolayers and by electronic cell sizing of suspended cells. Treatment of the cells with agents that stimulate Na-K-Cl cotransport activity was found to increase cell volume, whereas cotransport-inhibiting agents decreased cell volume. Exposure of the cells to hypertonic medium caused a rapid decrease in cell volume, followed by a regulatory volume increase that was greatly attenuated by bumetanide. The volume recovery was partially inhibited by the Na-H exchange inhibitor amiloride and was nearly abolished by bumetanide and amiloride in combination. Endothelial cells of pulmonary artery and cerebral microvessels were also found to exhibit increased Na-K-Cl cotransport activity on exposure to hypertonic media. These findings suggest that Na-K-Cl cotransport is of major importance in endothelial cell volume regulation.

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