Ca2+ uptake in GH3 cells during hypotonic swelling: the sensory role of stretch-activated ion channels

1996 ◽  
Vol 270 (6) ◽  
pp. C1790-C1798 ◽  
Author(s):  
Y. Chen ◽  
S. M. Simasko ◽  
J. Niggel ◽  
W. J. Sigurdson ◽  
F. Sachs
Keyword(s):  
Volume Regulation ◽  
Cell Swelling ◽  
Gh3 Cells ◽  
Membrane Tension ◽  
Hypotonic Cell Swelling ◽  
Stretch Activated Channels ◽  
Ca2 Channels ◽  
Hypotonic Swelling ◽  
Volume Decrease

Hypotonic cell swelling triggers an increase in intracellular Ca2+ concentration that is deemed responsible for the subsequent regulated volume decrease in many cells. To understand the mechanisms underlying this increase, we have studied the Ca2+ sources that contribute to hypotonic cell swelling-induced Ca2+ increase (HICI) in GH3 cells. Fura 2 fluorescence of cell populations revealed that extracellular, but not intracellular, stores of Ca2+ were required. HICI was abolished by nifedipine, a blocker of L-type Ca2+ channels, and Gd3+, a nonspecific blocker of stretch-activated channels (SACs), suggesting two components for the Ca2+ membrane pathway: L-type Ca2+ channels and SACs. Using HICI as an assay, we found that venom from the spider Grammostola spatulata could block HICI without blocking L-type Ca2+ channels. The venom did, however, block SAC activity. This suggests that Ca(2+)-permeable SACs, rather than L-type Ca2+ channels, are the sensing elements for HICI. These results support the model for volume regulation in which SACs, activated by an increase of the membrane tension during hypotonic cell swelling, trigger HICI, leading to a volume decrease.

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.

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.

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+.

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.

scholarly journals Cell swelling-induced ATP release and gadolinium-sensitive channels

2002 ◽  
Vol 282 (1) ◽  
pp. C219-C226 ◽  
Author(s):  
Francis Boudreault ◽  
Ryszard Grygorczyk
Keyword(s):  
Membrane Lipids ◽  
Atp Release ◽  
A549 Cells ◽  
Cell Swelling ◽  
Specific Effects ◽  
Underlying Mechanisms ◽  
Dependent Processes ◽  
Atp Efflux ◽  
Stretch Activated Channels ◽  
Hypotonic Swelling

ATP release induced by hypotonic swelling is an ubiquitous phenomenon in eukaryotic cells, but its underlying mechanisms are poorly defined. A mechanosensitive (MS) ATP channel has been implicated because gadolinium (Gd3+), an inhibitor of stretch-activated channels, suppressed ATP efflux monitored by luciferase bioluminescence. We examined the effect of Gd3+on luciferase bioluminescence and on ATP efflux from hypotonically swollen cells. We found that luciferase was inhibited by ≤10 μM Gd3+, and this may have contributed to the previously reported inhibition of ATP release. In ATP efflux experiments, luciferase inhibition could be prevented by chelating Gd3+with EGTA before luminometric ATP determinations. Using this approach, we found that 10–100 μM Gd3+, i.e., concentrations typically used to block MS channels, actually stimulated hypotonically induced ATP release from fibroblasts. Inhibition of ATP release required at least 500, 200, or 100 μM Gd3+ for fibroblasts, A549 cells, and 16HBE14o− cells, respectively. Such biphasic and cell-specific effects of Gd3+ are most consistent with its action on membrane lipids and membrane-dependent processes such as exocytosis.

Effects of extracellular nucleotides and their hydrolysis products on regulatory volume decrease of trout hepatocytes

2004 ◽  
Vol 287 (4) ◽  
pp. R833-R843 ◽  
Author(s):  
D. E. Pafundo ◽  
P. Mut ◽  
M. Pérez Recalde ◽  
R. M. González-Lebrero ◽  
V. Fachino ◽  
...  
Keyword(s):  
Regulatory Volume Decrease ◽  
Extracellular Nucleotides ◽  
Hypotonic Medium ◽  
Adenosine Uptake ◽  
Extracellular Release ◽  
Hypotonic Swelling ◽  
Volume Decrease

In trout hepatocytes, hypotonic swelling is followed by a compensatory shrinkage called regulatory volume decrease (RVD). It has been postulated that extracellular ATP and other nucleotides may interact with type 2 receptors (P2) to modulate this response. In addition, specific ectoenzymes hydrolyze ATP sequentially down to adenosine, which may bind to type 1 receptors (P1) and also influence RVD. Accordingly, in this study, we assessed the role of extracellular nucleoside 5′-tri- and diphosphates and of adenosine on RVD of trout hepatocytes. The extent of RVD after 40 min of maximum swelling was denoted as RVD40, whereas the initial rate of RVD was called vRVD. In the presence of hypotonic medium (60% of isotonic), hepatocytes swelled 1.6 times followed by vRVD of 1.7 min−1 and RVD40 of 60.2%. ATP, UTP, UDP, or ATPγS (P2 agonists; 5 μM) increased vRVD 1.5–2 times, whereas no changes were observed in the values of RVD40. Addition of 100 μM suramin or cibacron blue (P2 antagonists) to the hypotonic medium produced no effect on vRVD but a 53–58% inhibition of RVD40. Incubation of hepatocytes in the presence of either 5 μM [γ-32P]ATP or [α-32P]ATP induced the extracellular release of [γ-32P]Pi (0.21 nmol·10−6 cells−1·min−1) and [α-32P]Pi (∼8 × 10−3 nmol·10−6 cells−1·min−1), suggesting the presence of ectoenzymes capable of fully dephosphorylating ATP. Concerning the effect of P1 activation on RVD, 5 μM adenosine, both in the presence and absence of 100 μM S-(4-nitrobenzil)-6-tioinosine (a blocker of adenosine uptake), decreased RVD40 by 37–44%, whereas 8-phenyl theophylline, a P1 antagonist, increased RVD40 by 15%. Overall, results indicate that ATP, UTP, and UDP, acting via P2, are important factors promoting RVD of trout hepatocytes, whereas adenosine binding to P1 inhibits this process.

Involvement of calcium and cytoskeleton in gallbladder epithelial cell volume regulation

1985 ◽  
Vol 248 (1) ◽  
pp. C27-C36 ◽  
Author(s):  
J. K. Foskett ◽  
K. R. Spring
Keyword(s):  
Volume Regulation ◽  
Cytochalasin B ◽  
Morphological Changes ◽  
Regulatory Volume Decrease ◽  
Cell Volume Regulation ◽  
Cell Swelling ◽  
Bathing Solution ◽  
Calcium Dependent ◽  
Cytoskeletal Elements

The importance of calcium and cellular cytoskeletal elements in the activation or control of volume regulation by epithelial cells was explored in Necturus gallbladder. Gallbladder cells have been previously shown to rapidly readjust their volumes to control size after osmotic perturbation of the mucosal bathing solution. Removal of calcium from the perfusates caused dramatic morphological changes that prevented assessment of the role of extracellular calcium in volume regulation. The regulatory volume increase (RVI) that follows shrinkage of the cell due to perfusion of a hypertonic mannitol solution is insensitive to agents that interfere with cell calcium- or calmodulin-mediated events (quinidine, trifluoperazine) and is not blocked by agents that cause changes in the cytoskeleton (colchicine, cytochalasin B). Osmotically induced cell swelling is followed by regulatory volume decrease (RVD), which is inhibited by agents that interfere with calcium-dependent processes (quinidine, trifluoperazine) and by the microfilament inhibitor, cytochalasin B. These results indicate that RVD depends on calcium, calmodulin, and an intact microfilament network, whereas RVI is independent of these factors.

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.

The Src family kinases: distinct functions of c-Src, Yes, and Fyn in the liver

2013 ◽  
Vol 4 (2) ◽  
pp. 129-142 ◽  
Author(s):  
Roland Reinehr ◽  
Annika Sommerfeld ◽  
Dieter Häussinger
Keyword(s):  
Regulatory Volume Decrease ◽  
Death Receptor ◽  
Growth Factor Receptor ◽  
Src Family Kinases ◽  
Cell Swelling ◽  
Receptor Ligands ◽  
Liver Functions ◽  
Epidermal Growth ◽  
Volume Decrease

AbstractThe Src family kinases Yes, Fyn, and c-Src play a pivotal role in regulating diverse liver functions such as bile flow, proteolysis, apoptosis, and proliferation and are regulated by anisoosmotic cell volume changes, death receptor ligands, and bile acids. For example, cell swelling leads to an integrin-sensed and focal adhesion kinase-mediated activation of c-Src-triggering choleresis, proteolysis inhibition, regulatory volume decrease via p38MAPK and proliferation via the activation of the epidermal growth factor receptor and extracellular regulated kinases 1 and 2. In contrast, hepatocyte shrinkage generates an almost instantaneous oxidative stress response that triggers the activation of c-Jun N-terminal kinase and the Src family kinases Fyn and Yes. Whereas Fyn activation mediates cholestasis, Yes triggers CD95 activation and apoptosis. This review will discuss the role of Src family kinases in the regulation of liver function with emphasis on their role in osmo-signaling and bile acid signaling.

Regulatory volume decrease in frog retinal pigment epithelium

1995 ◽  
Vol 268 (1) ◽  
pp. C89-C100 ◽  
Author(s):  
J. S. Adorante
Keyword(s):  
Cell Volume ◽  
Volume Regulation ◽  
Retinal Pigment Epithelial ◽  
Retinal Pigment ◽  
Control Level ◽  
Regulatory Volume Decrease ◽  
Cell Swelling ◽  
Rpe Cells ◽  
Pigment Epithelial ◽  
Volume Decrease

To measure changes in cell water during cell volume regulation, retinal pigment epithelial cells were loaded with tetramethylammonium (TMA). Regulatory volume decrease (RVD) in TMA-loaded retinal pigment epithelial (RPE) cells was measured using double-barreled K(+)-specific microelectrodes. Hyposmotic removal of 12.5 mM NaCl from the apical bath caused bullfrog RPE cells to rapidly swell by approximately 10% and to recover to control level within 10-15 min. Hyposmotic RVD was inhibited by 5 mM basal but not apical BaCl2. Raising K+ in the basal bath from 2 to 12 mM also inhibited RVD. Hyposmotic swelling was accompanied by an increase in the ratio of apical to basolateral membrane resistance (Ra/Rb). The swelling-induced increase in Ra/Rb was inhibited by 5 mM BaCl2. Together, the above findings suggest that hyposmotic swelling enhances basolateral K+ conductance such that K+ and presumably anion efflux mediate net solute and water loss during RVD. RPE cells can also regulate their volume when swollen in isosmotic Ringer solution under certain conditions. When urea or apical HCO3- was used to induce cell swelling, RPE cells underwent an RVD. In contrast, isosmotic elevation of apical K+ from 2 to 5 mM resulted in an increase in RPE cell volume with no subsequent RVD. Thus the method used to swell RPE cells is an important determinant of RVD. Because changes in RPE cell volume in vivo may alter the volume and composition of the extracellular (subretinal) space surrounding the photoreceptors, isosmotic volume regulation may play an important physiological role in maintaining the integrity and health of the neural retina under normal and pathophysiological conditions.

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