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Osmotic Swelling (osmotic + swelling)
Selected AbstractsA role for the volume regulated anion channel in volume regulation in the murine CNS cell line, CADACTA PHYSIOLOGICA, Issue 2 2010V. L. Harvey Abstract Aim:, The role of the volume regulated anion channel (VRAC) in a model CNS neuronal cell line, CAD, was investigated. Methods:, Changes in cell volume following hypotonic challenges were measured using a video-imaging technique. The effect of the Cl, channel antagonists tamoxifen (10 ,m) and 4,4,-diisothiocyanatostilbene-2,2,-disulphonic acid (DIDS; 100 ,m) on regulatory volume decrease (RVD) were measured. The whole-cell voltage-clamp technique was used to characterize IClswell, the current underlying the VRAC. Results:, Using the video-imaging technique, CAD cells were found to swell and subsequently exhibit RVD when subjected to a sustained hypotonic challenge from 300 mOsmol kg,1 H2O to 210 mOsmol kg,1 H2O. In the presence of tamoxifen (10 ,m) or DIDS (100 ,m) RVD was abolished, suggesting a role for the VRAC. A hypotonic solution (230 mOsmol kg,1 H2O) evoked IClswell, an outwardly rectifying current displaying time-independent activation, which reversed upon return to isotonic conditions. The reversal potential (Erev) for IClswell was ,14.7 ± 1.4 mV, similar to the theoretical Erev for a selective Cl, conductance. IClswell was inhibited in the presence of DIDS (100 ,m) and tamoxifen (10 ,m), the DIDS inhibition being voltage dependent. Conclusions:, Osmotic swelling elicits an outwardly rectifying Cl, conductance in CAD cells. The IClswell observed in these cells is similar to that observed in other cells, and is likely to provide a pathway for the loss of Cl, which leads to water loss and RVD. As ischaemia, brain trauma, hypoxia and other brain pathologies can cause cell swelling, CAD cells represent a model cell line for the study of neuronal cell volume regulation. [source] Symmetric Wrinkling Patterns: Diffusion-Controlled, Self-Organized Growth of Symmetric Wrinkling Patterns (Adv. Mater.ADVANCED MATERIALS, Issue 13 200913/2009) Irradiation of thin polystyrene films leads to the formation of a stiff skin layer, which can dynamically wrinkle under osmotic swelling of a small molecule penetrant from localized defects in the film. As shown by Christopher Stafford and co-workers on p. 1358, these wrinkled surfaces display a rich diversity of pattern symmetries that are not readily accessible by any other route. [source] Glial cell-derived glutamate mediates autocrine cell volume regulation in the retina: activation by VEGFJOURNAL OF NEUROCHEMISTRY, Issue 2 2008Antje Wurm Abstract Astroglial cells are a source for gliotransmitters such as glutamate and ATP. We demonstrate here that gliotransmitters have autocrine functions in the regulation of cellular volume. Hypoosmotic stress in the presence of inflammatory mediators or oxidative stress, and during blockade or down-regulation of potassium channels, induces swelling of retinal glial cells. Vascular endothelial growth factor inhibits the osmotic swelling of glial cells in retinal slices or isolated cells. This effect was mediated by a kinase domain region/flk-1 receptor-evoked calcium dependent release of glutamate from glial cells, and subsequent stimulation of glial group I/II metabotropic glutamate receptors. Activation of kinase domain region/flk-1 or glutamate receptors evoked an autocrine swelling-inhibitory purinergic signaling cascade that was calcium-independent. This cascade involved the release of ATP and adenosine, and the activation of purinergic P2Y1 and adenosine A1 receptors, resulting in the opening of potassium and chloride channels and inhibition of cellular swelling. The glutamatergic-purinergic regulation of the glial cell volume may be functionally important in the homeostasis of the extracellular space volume during intense neuronal activation which is associated with a swelling of neuronal cell structures in the retina. However, glial cell-derived glutamate may also contribute to the swelling of activated neurons since metabolic poisoning of glial cells by iodoacetate inhibits the neuronal cell swelling mediated by activation of ionotropic glutamate receptors. [source] The concerted action of the Helicobacter pylori cytotoxin VacA and of the v-ATPase proton pump induces swelling of isolated endosomesCELLULAR MICROBIOLOGY, Issue 6 2007Christophe Genisset Summary The vacuolating cytotoxin (VacA) is a major virulence factor of Helicobacter pylori, the bacterium associated to gastroduodenal ulcers and stomach cancers. VacA induces formation of cellular vacuoles that originate from late endosomal compartments. VacA forms an anion-selective channel and its activity has been suggested to increase the osmotic pressure in the lumen of these acidic compartments, driving their swelling to vacuoles. Here, we have tested this proposal on isolated endosomes that allow one to manipulate at will the medium. We have found that VacA enhances the v-ATPase proton pump activity and the acidification of isolated endosomes in a Cl, dependent manner. Other counter-anions such as pyruvate, Br,, I, and SCN, can be transported by VacA with stimulation of the v-ATPase. The VacA action on isolated endosomes is associated with their increase in size. Single amino acid substituted VacA with no channel-forming and vacuolating activity is unable to induce swelling of endosomes. These data provide a direct evidence that the transmembrane VacA channel mediates an influx of anions into endosomes that stimulates the electrogenic v-ATPase proton pump, leading to their osmotic swelling and transformation into vacuoles. [source] | ||||||||||