Cell volume control in phospholemman (PLM) knockout mice: do cardiac myocytes demonstrate a regulatory volume decrease and is this influenced by deletion of PLM?

2009 ◽  
Vol 94 (3) ◽  
pp. 330-343 ◽  
Author(s):  
James R. Bell ◽  
David Lloyd ◽  
Claire L. Curl ◽  
Lea M. D. Delbridge ◽  
Michael J. Shattock
Keyword(s):  
Cell Volume ◽  
Cardiac Myocytes ◽  
Knockout Mice ◽  
Regulatory Volume Decrease ◽  
Volume Control ◽  
Volume Decrease ◽  
Cell Volume Control

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.

scholarly journals Release of taurine and glutamate contributes to cell volume regulation in human retinal Müller cells: differences in modulation by calcium

2018 ◽  
Vol 120 (3) ◽  
pp. 973-984 ◽  
Author(s):  
Vanina Netti ◽  
Alejandro Pizzoni ◽  
Martha Pérez-Domínguez ◽  
Paula Ford ◽  
Herminia Pasantes-Morales ◽  
...  
Keyword(s):  
Cell Volume ◽  
Regulatory Volume Decrease ◽  
Cell Volume Regulation ◽  
Müller Cells ◽  
Anion Channel ◽  
Müller Cell ◽  
Regulatory Mechanisms ◽  
Muller Cells ◽  
Muller Cell ◽  
Volume Decrease

Neuronal activity in the retina generates osmotic gradients that lead to Müller cell swelling, followed by a regulatory volume decrease (RVD) response, partially due to the isoosmotic efflux of KCl and water. However, our previous studies in a human Müller cell line (MIO-M1) demonstrated that an important fraction of RVD may also involve the efflux of organic solutes. We also showed that RVD depends on the swelling-induced Ca2+ release from intracellular stores. Here we investigate the contribution of taurine (Tau) and glutamate (Glu), the most relevant amino acids in Müller cells, to RVD through the volume-regulated anion channel (VRAC), as well as their Ca2+ dependency in MIO-M1 cells. Swelling-induced [3H]Tau/[3H]Glu release was assessed by radiotracer assays and cell volume by fluorescence videomicroscopy. Results showed that cells exhibited an osmosensitive efflux of [3H]Tau and [3H]Glu (Tau > Glu) blunted by VRAC inhibitors 4-(2-butyl-6,7-dichloro-2-cyclopentylindan-1-on-5-yl)-oxybutyric acid and carbenoxolone reducing RVD. Only [3H]Tau efflux was mainly dependent on Ca2+ release from intracellular stores. RVD was unaffected in a Ca2+-free medium, probably due to Ca2+-independent Tau and Glu release, but was reduced by chelating intracellular Ca2+. The inhibition of phosphatidylinositol-3-kinase reduced [3H]Glu efflux but also the Ca2+-insensitive [3H]Tau fraction and decreased RVD, providing evidence of the relevance of this Ca2+-independent pathway. We propose that VRAC-mediated Tau and Glu release has a relevant role in RVD in Müller cells. The observed disparities in Ca2+ influence on amino acid release suggest the presence of VRAC isoforms that may differ in substrate selectivity and regulatory mechanisms, with important implications for retinal physiology. NEW & NOTEWORTHY The mechanisms for cell volume regulation in retinal Müller cells are still unknown. We show that swelling-induced taurine and glutamate release mediated by the volume-regulated anion channel (VRAC) largely contributes the to the regulatory volume decrease response in a human Müller cell line. Interestingly, the hypotonic-induced efflux of these amino acids exhibits disparities in Ca2+-dependent and -independent regulatory mechanisms, which strongly suggests that Müller cells may express different VRAC heteromers formed by the recently discovered leucine-rich repeat containing 8 (LRRC8) proteins.

scholarly journals Mathematical Modeling of Cell Volume Control

2020 ◽  
Vol 118 (3) ◽  
pp. 461a
Author(s):  
Maria Jesus Munoz Lopez ◽  
Yoichiro Mori
Keyword(s):  
Mathematical Modeling ◽  
Cell Volume ◽  
Volume Control ◽  
Cell Volume Control

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.

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 Spatial Organization of Calcium Signaling Involved in Cell Volume Control in the Fucus Rhizoid.

1996 ◽  
pp. 2015-2031 ◽  
Author(s):  
A. R. Taylor ◽  
NFH. Manison ◽  
C. Fernandez ◽  
J. Wood ◽  
C. Brownlee
Keyword(s):  
Calcium Signaling ◽  
Cell Volume ◽  
Spatial Organization ◽  
Volume Control ◽  
Cell Volume Control

Cell volume increase and extracellular Ca2+ are needed for hyposmotically induced prolactin release in tilapia

2003 ◽  
Vol 284 (5) ◽  
pp. C1280-C1289 ◽  
Author(s):  
A. P. Seale ◽  
N. H. Richman ◽  
T. Hirano ◽  
I. Cooke ◽  
E. G. Grau
Keyword(s):  
Cell Volume ◽  
Regulatory Volume Decrease ◽  
Volume Increase ◽  
Solute Retention ◽  
Intracellular Ca ◽  
Freshwater Adaptation ◽  
Euryhaline Teleost ◽  
Volume Decrease

In the tilapia ( Oreochromis mossambicus), as in many euryhaline teleost fish, prolactin (PRL) plays a central role in freshwater adaptation, acting on osmoregulatory surfaces to reduce ion and water permeability and increase solute retention. Consistent with these actions, PRL release is stimulated as extracellular osmolality is reduced both in vivo and in vitro. In the current experiments, a perfusion system utilizing dispersed PRL cells was developed for permitting the simultaneous measurement of cell volume and PRL release. Intracellular Ca2+ was monitored using fura 2-loaded cells under the same conditions. When PRL cells were exposed to hyposmotic medium, an increase in PRL cell volume preceded the increase in PRL release. Cell volume increased in proportion to decreases of 15 and 30% in osmolality. However, regulatory volume decrease was clearly seen only after a 30% reduction. The hyposmotically induced PRL release was sharply reduced in Ca2+-deleted hyposmotic medium, although cell volume changes were identical to those observed in normal hyposmotic medium. In most cells, a rise in intracellular Ca2+ concentration ([Ca2+]i) during hyposmotic stimulation was dependent on the availability of extracellular Ca2+, although small transient increases in [Ca2+]i were sometimes observed upon introduction of Ca2+-deleted media of the same or reduced osmolality. These results indicate that an increase in cell size is a critical step in the transduction of an osmotic signal into PRL release and that the hyposmotically induced increase in PRL release is greatly dependent on extracellular Ca2+.

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