Hypotonically induced calcium increase and regulatory volume decrease in newborn rat cardiomyocytes

1998 ◽  
Vol 436 (4) ◽  
pp. 565-574 ◽  
Author(s):  
Karima Taouil ◽  
Raffaella Giancola ◽  
Jean-Emile Morel ◽  
P. Hannaert
Keyword(s):  
Regulatory Volume Decrease ◽  
Newborn Rat ◽  
Rat Cardiomyocytes ◽  
Volume Decrease

scholarly journals KCNQ channels are involved in the regulatory volume decrease response in primary neonatal rat cardiomyocytes

2007 ◽  
Vol 1773 (6) ◽  
pp. 764-773 ◽  
Author(s):  
Kirstine Calloe ◽  
Morten Schak Nielsen ◽  
Morten Grunnet ◽  
Nicole Schmitt ◽  
Nanna Koschmieder Jorgensen
Keyword(s):  
Regulatory Volume Decrease ◽  
Neonatal Rat ◽  
Rat Cardiomyocytes ◽  
Kcnq Channels ◽  
Neonatal Rat Cardiomyocytes ◽  
Volume Decrease

Human Platelets Exposed to Mechanical Stresses Express a Potent Lipoxygenase Product

1992 ◽  
Vol 68 (05) ◽  
pp. 589-594 ◽  
Author(s):  
Alon Margalit ◽  
Avinoam A Livne
Keyword(s):  
Regulatory Volume Decrease ◽  
Human Platelets ◽  
Mechanical Stresses ◽  
Arterial Stenosis ◽  
Platelet Suspension ◽  
Suspension Flows ◽  
Lipoxygenase Product ◽  
Pathological Conditions ◽  
K Permeability ◽  
Volume Decrease

SummaryHuman platelets exposed to hypotonicity undergo regulatory volume decrease (RVD), controlled by a potent, yet labile, lipoxygenase product (LP). LP is synthesized and excreted during RVD affecting selectively K+ permeability. LP is assayed by its capacity to reconstitute RVD when lipoxygenase is blocked. Centrifugation for preparing washed platelets (1,550 × g, 10 min) is sufficient to express LP activity, with declining potency in repeated centrifugations, indicating that it is not readily replenish-able. When platelet suspension flows in a vinyl tubing (1 mm i.d.), at physiological velocity, controlled at 90–254 cm/s, LP formation increases as a function of velocity but declines as result of increasing the tubing length. Stirring the platelets in an aggregometer cuvette for 30 s, yields no LP unless the stirring is intermittent. No associated platelet lysis or aggregation are observed following the mechanical stress applications. These results demonstrate that although mechanical stresses result in LP production, the mode of its application plays a major role. These results may indicate that LP is synthesized under pathological conditions and could be of relevance to platelets behavior related to arterial stenosis.

LRRC8A is essential for swelling‐activated chloride current and for regulatory volume decrease in astrocytes

2018 ◽  
Vol 33 (1) ◽  
pp. 101-113 ◽  
Author(s):  
Francesco Formaggio ◽  
Emanuela Saracino ◽  
Maria Grazia Mola ◽  
Shreyas Balachandra Rao ◽  
Mahmood Amiry-Moghaddam ◽  
...  
Keyword(s):  
Regulatory Volume Decrease ◽  
Chloride Current ◽  
Volume Decrease

Extracellular pH alkalinization by Cl−/HCO3− exchanger is crucial for TASK2 activation by hypotonic shock in proximal cell lines from mouse kidney

2007 ◽  
Vol 292 (2) ◽  
pp. F628-F638 ◽  
Author(s):  
S. L'Hoste ◽  
H. Barriere ◽  
R. Belfodil ◽  
I. Rubera ◽  
C. Duranton ◽  
...  
Keyword(s):  
Cell Lines ◽  
Regulatory Volume Decrease ◽  
Inhibitory Effect ◽  
Buffering Capacity ◽  
Mouse Kidney ◽  
Wild Type ◽  
Cytosolic Ph ◽  
Hypotonic Shock ◽  
External Ph ◽  
Volume Decrease

We have previously shown that K+-selective TASK2 channels and swelling-activated Cl− currents are involved in a regulatory volume decrease (RVD; Barriere H, Belfodil R, Rubera I, Tauc M, Lesage F, Poujeol C, Guy N, Barhanin J, Poujeol P. J Gen Physiol 122: 177–190, 2003; Belfodil R, Barriere H, Rubera I, Tauc M, Poujeol C, Bidet M, Poujeol P. Am J Physiol Renal Physiol 284: F812–F828, 2003). The aim of this study was to determine the mechanism responsible for the activation of TASK2 channels during RVD in proximal cell lines from mouse kidney. For this purpose, the patch-clamp whole-cell technique was used to test the effect of pH and the buffering capacity of external bath on Cl− and K+ currents during hypotonic shock. In the presence of a high buffer concentration (30 mM HEPES), the cells did not undergo RVD and did not develop outward K+ currents (TASK2). Interestingly, the hypotonic shock reduced the cytosolic pH (pHi) and increased the external pH (pHe) in wild-type but not in cftr −/− cells. The inhibitory effect of DIDS suggests that the acidification of pHi and the alkalinization of pHe induced by hypotonicity in wild-type cells could be due to an exit of HCO3−. In conclusion, these results indicate that Cl− influx will be the driving force for HCO3− exit through the activation of the Cl−/HCO3− exchanger. This efflux of HCO3− then alkalinizes pHe, which in turn activates TASK2 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.

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.

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