The Diversity of Volume Regulatory Mechanisms

Läng, Florian; Busch, Gillian L.; Völkl, Harald

doi:10.1159/000016269

Cited by 294 publications

(248 citation statements)

References 923 publications

Supporting

Mentioning

236

Contrasting

Unclassified

Order By: Relevance

“…The mechanisms involved in the osmotic response and their interactions are unknown but changes in cell volume could be partly involved. The volume of disc cells, like those of other mammalian cells, 24 alters with change in extracellular osmolarity; volume falls under hyperosmotic conditions through fluid loss and cells swell under hypo-osmotic conditions because of water imbibition; 6,7,25 these finding were confirmed in our study histologically and by SEM (not shown).…”

Section: Discussionsupporting

confidence: 80%

Influence of extracellular osmolarity and mechanical stimulation on gene expression of intervertebral disc cells

Wuertz

Urban

Klasen

et al. 2007

Journal Orthopaedic Research

135

139

View full text Add to dashboard Cite

Intervertebral discs (IVD) have a higher extracellular osmolarity than most other tissues; moreover their osmolarity changes by around 25% during each diurnal cycle. In this study, changes in aggrecan, collagen I and collagen II expression of IVD cells were examined after exposure to osmotic environment alterations or mechanical stimulation under different osmotic conditions. Human and bovine IVD cells seeded in three-dimensional (3D) collagen type I matrices were cultured under hypo-osmotic (300 mOsm), iso-osmotic (400 mOsm), or hyperosmotic (500 mOsm) conditions. Osmolarity-induced changes in gene expression of IVD cells were measured after 5 days. Loadinduced changes in gene expression under the different osmotic conditions were measured after application of hydrostatic pressure (0.25 MPa, 0.1 Hz, 30 min) or cyclic strain (4%, 1 Hz, 24 h). The results showed that IVD cells respond strongly to changes in the osmotic environment by altering mRNA expression. Human cells cultured over 5 days increased expression of aggrecan and collagen II in both nucleus and annulus cells under increasing osmolarity. In contrast, collagen I expression was inhibited at high osmolarity in both cell types. Mechanically induced alterations in gene expression appear to have only modest effects on matrix protein expression, but the same stimulus partly resulted in an inhibition or stimulation of gene expression, depending on the osmotic conditions. This study showed that the osmotic environment does not only have an appreciable effect on gene expression but also affects responses to mechanical stimuli. This suggests that the osmotic conditions cannot be ignored when examining physiological and pathological behavior of IVD cells.

show abstract

Section: Discussionsupporting

confidence: 80%

Influence of extracellular osmolarity and mechanical stimulation on gene expression of intervertebral disc cells

Wuertz

Urban

Klasen

et al. 2007

Journal Orthopaedic Research

135

139

View full text Add to dashboard Cite

show abstract

“…These ions are accompanied by osmotically obliged water, thus increasing cell volume (Hoffmann et al, 2009). In most mammalian cells, the principle inorganic ions involved are Na þ and Cl À , whose transport into the cell is mediated by the coupled activities of Na þ /H þ and Cl À /HCO 3 À exchange (Lang et al, 1998;Wehner et al, 2003;Hoffmann et al, 2009). Upon a decrease in cell volume, Na þ /H þ exchangers (NHEs) of the Slc9 gene family (Alexander and Grinstein, 2006), mainly NHE1, become activated, producing both Na þ influx and an increase in intracellular pH (pH i ) due to H þ efflux (Orlowski and Grinstein, 2004).…”

Section: Cell Volume Regulationmentioning

confidence: 99%

“…1D,E), a diverse array of small, neutral organic compounds that can provide intracellular osmotic support without perturbing cell function, even at very high intracellular concentrations (Yancey et al, 1982;GarciaPerez and Burg, 1991). A number of cell types use organic osmolytes for cell volume homeostasis (Yancey, 1994;Lang et al, 1998), allowing the cell to maintain intracellular ionic strength at an optimal level while permitting the cell to independently control intracellular osmolarity. Most organic osmolytes accumulated by cells are transported from the external environment (Yancey et al, 1982;Kwon and Handler, 1995;Kempf and Bremer, 1998).…”

Section: Cell Volume Regulationmentioning

confidence: 99%

Cell volume regulation in mammalian oocytes and preimplantation embryos

Baltz

Zhou

2012

Molecular Reproduction Devel

View full text Add to dashboard Cite

SUMMARYThe earliest stages of preimplantation embryos are particularly sensitive to increased osmolarity, even within the physiological range. This sensitivity contributed to persistent developmental arrest, even when embryos were cultured in vitro in older, conditioned culture media, and seems to arise when embryos at the 1-and 2-cell stages accumulate inorganic ions used for cell volume homeostasis at too high a level, through activation of coupled Na þ /H þ and HCO 3 À /Cl À exchange. Such accumulation of inorganic ions can be disruptive since, above a certain level, the increased ionic strength disrupts cellular biochemistry and macromolecular functions and alters membrane potential. To counter this, embryos have evolved mechanisms of cell volume regulation that are unique to early preimplantation embryogenesis. The primary role of these is glycine accumulation via the GLYT1 transporter, with a secondary contribution by betaine accumulation via the SIT1 transporter. Independent cell-volume regulation first arises in the oocyte only after ovulation is triggered, when the strong oocyte-zona pellucida adhesion present in germinal vesicle stage oocytes in the ovarian follicle is released and GLYT1 becomes activated to begin accumulating glycine. Open questions still remain regarding how these processes are regulated.Mol. Reprod. Dev. 79: 821-831, 2012. ß

show abstract

“…Acute volume perturbations are alleviated by quickly adjusting inorganic ion concentrations (Hallows and Knauf, 1994), but cells that are normally subject to high osmolarity instead require ''organic osmolytes,'' small uncharged organic compounds, to provide long-term intracellular osmotic support (Yancey et al, 1982;Garcia-Perez and Burg, 1991;Lang et al, 1998). This avoids the severe metabolic disruption caused by the substantially increased intracellular ionic strength that would be required to balance high osmolarity using inorganic ions.…”

mentioning

confidence: 99%

“…The requirement for organic osmolytes, and for these organic osmolyte transporters, is well established in cells subjected to hypertonicity, such as in the kidney. However, a range of cells not normally subject to osmotic stress also use organic osmolytes (Lang et al, 1998), and thus organic osmolytes and osmolyte transporters are likely to function in ''housekeeping'' cell volume regulation as well as in response to hypertonic conditions.…”

mentioning

confidence: 99%

The organic osmolytes betaine and proline are transported by a shared system in early preimplantation mouse embryos

Anas¹,

Hammer²,

Lever

et al. 2006

Journal Cellular Physiology

View full text Add to dashboard Cite

Betaine and proline protect preimplantation mouse embryos against increased osmolarity and decreased cell volume, implying that they may function as organic osmolytes. However, the transport system(s) that mediates their accumulation in fertilized eggs and early embryos was unknown, and previously identified mammalian organic osmolyte transporters could not account for their transport. Here, we report that there is a single saturable transport component shared by betaine and proline in 1-cell mouse embryos. A series of inhibitors had nearly identical effects on both betaine and proline transport by this system. In addition, K i values for reciprocal inhibition of betaine and proline transport were $100-300 mM, similar to K m values ($200-300 mM) for their transport, and both had similar maximal transport rates (V max ). The K i values for inhibition of betaine and proline transport by dimethylglycine were similar ($2 mM), further supporting transport of both substrates by a single transport system. Finally, betaine and proline transport each required Na þ -and Cl À . These data were consistent with a single, Na þ -and Cl À -requiring, betaine/proline transport system in 1-cell mouse embryos. While betaine was only transported by a single saturable system, we found an additional, less conspicuous proline transport route that was betaine-insensitive, Na þ -sensitive, and inhibited by alanine, leucine, cysteine, and methionine. Furthermore, we showed that betaine, like proline, is present in the mouse oviduct and thus could serve as a physiological substrate. Finally, accumulation of both betaine and proline increased with increasing osmolarity, consistent with a possible role as organic osmolytes in early embryos.

show abstract

The Diversity of Volume Regulatory Mechanisms

Cited by 294 publications

References 923 publications

Influence of extracellular osmolarity and mechanical stimulation on gene expression of intervertebral disc cells

Influence of extracellular osmolarity and mechanical stimulation on gene expression of intervertebral disc cells

Cell volume regulation in mammalian oocytes and preimplantation embryos

The organic osmolytes betaine and proline are transported by a shared system in early preimplantation mouse embryos

Contact Info

Product

Resources

About