Effects Of Osmotic Changes Research Articles

Morphology as indicator of adaptive changes of model tissues in osmotically and chemically changing environments

We investigate the formation and maintenance of the homeostatic state in the case of 2D epithelial tissues following an induction of hyperosmotic conditions, using media enriched with 80 to 320 mOsm of mannitol, NaCl, and urea. We characterise the changes in the tissue immediately after the osmotic shock, and follow it until the new homeostatic state is formed. We characterise changes in cooperative motility and proliferation pressure in the tissue upon treatment with the help of a theoretical model based on the delayed Fisher-Kolmogorov formalism, where the delay in density evolution is induced by the the finite time of the cell division. Finally we explore the adaptation of the homeostatic tissue to highly elevated osmotic conditions by evaluating the morphology and topology of cells after 20 days in incubation. We find that hyperosmotic environments together with changes in the extracellular matrix induce different mechanical states in viable tissues, where only some remain functional. The perspective is a relation between tissue topology and function, which could be explored beyond the scope of this manuscript.Experimental investigation of morphological effect of change of osmotic conditions on long-term tissue morphology and topology Effect of osmotic changes on transient tissue growth behaviour Analysis of recovery process of tissues post-osmotic-shock Toxicity limits of osmolytes in mid- to long-term tissue evolution Tissue adaptation to physiological changes in environment Long-term tissue stabilisation under altered osmotic conditions.

O-173 Cellular and developmental damage from oocyte cryopreservation

Abstract Compared to somatic or sperm cells, mammalian oocytes are much more sensitive to cryopreservation mainly because of the large volume, cytoskeleton, and presence of the zona pellucida. Connections with the surrounding cumulus cells also are challenging to preserve in immature oocytes. Besides the genetic and epigenetic information enclosed in the nucleus, oocytes contain organelles and cytoplasmic factors that are necessary for the early embryo development. Therefore, exposure to cryoprotectant and freezing temperatures can easily damage the oocyte’s complex cellular structure and developmental competence, which leads to poor success in fertilization, lower embryo quality, and reduced pregnancy rates. Using the domestic cat as a model, our laboratory has studied damages in cumulus-oocyte complexes (immature oocytes) occurring at each step of the cryopreservation process. Specifically, this included the impact of cryoprotectants on microtubules, the effect of osmotic changes on the overall structures, as well as sensitivity of the nuclear chromatin and epigenetic patterns to freezing temperatures. Based on those findings, it has been possible to design mitigating solutions like customized ultra-rapid freezing or vitrification protocols, Laser-warming methods, or post-warming reanimations. New horizons have also been explored to move away from issues and limitations related to cryopreservation. Approaches like storage of oocytes for the long-term at non-freezing temperatures are currently being developed based on encouraging data generated in preliminary studies. For instance, incorporation of trehalose into the oocyte followed by microwave-assisted dehydration can allow to remove enough water while creating a protective trehalose glass compatible with survival and storage at non-freezing temperatures. Interestingly, transcriptomic and proteomic studies have already shown that stresses and damages induced by dehydration versus cryopreservation are different and may be easier to overcome.

Aquaporin expression in breast cancer and their involvement in bleb formation, cell motility and invasion in endocrine resistant variant cells.

Estrogen receptor (ER)‑silenced breast cancer cell lines exhibit endocrine resistance and morphological changes from an epithelial to a mesenchymal phenotype. These cells also display increased motility and invasive properties that are further accentuated by exposure to an alkaline pH, exhibiting dynamic plasma membrane blebbing and cytoplasmic streaming. These latter morphological changes are hypothesized to involve substantial water movement across the plasma membrane, contributing to bleb formation; this may involve aquaporin channel proteins(AQPs). AQP1, 3, 4 and5 expression/localization was examined via reverse transcription‑quantitative PCR, western blotting and confocal microscopy in endocrine‑sensitive(YS1.2) and ‑resistant (pII and MDA‑MB‑231) breast cancer cells, as well as normal breast epithelial cells(MCF10A). The effects of osmotic changes on bleb formation were examined via live cell imaging. AQP3 protein expression was knocked down by small interfering RNA(siRNA) transfection, and the effect of its reduced expression on bleb formation, cell motility and invasion were determined via immunofluorescence, scratch and Cultrex assays, respectively. Expression of the four AQPs varied across the different cell lines, and exhibited nuclear, cytoplasmic and membranous localization. Osmotic changes affected the formation of blebs. In pIIcells exposed to alkaline pH, AQP3 was observed to be redistributed from the nucleus into the newly formed blebs. siRNA‑mediated knockdown of AQP3 in pIIcells significantly reduced cellular blebbing induced by alkaline pH, as well as motility and invasion. These data suggested that AQP3, and potentially other aquaporins, may participate in the processes leading to blebbing of endocrine‑resistant cells which is proposed to be a mechanism that drives tumor metastasis.

Effects of Osmolality on Paracellular Transport in MDCK II Cells.

Epithelia separate apical and basal compartments, and movement of substances via the paracellular pathway is regulated by tight junctions. Claudins are major constituents of tight junctions and involved in the regulation of tight junction permeability. On the other hand, the osmolality in the extracellular environment fluctuates in association with life activity. However, effects of osmotic changes on the permeaibility of claudins are poorly understood. Therefore, we investigated the effects of osmotic changes on the paracellular transport in MDCK II cells. Interestingly, apical hyposmolality decreased cation selectivity in the paracellular pathway gradually with time, and the elimination of the osmotic gradient promptly restored the cation selectivity. Apical hyposmolality also induced bleb formation at cell-cell contacts and changed the shape of cell-cell contacts from a jagged pattern to a slightly linear pattern. In claudin-2 knockout MDCK II cells, the decrease of cation selectivity, the bleb formation, nor the changes in the shape of cell-cell contacts was observed under the apical hyposmolality. Our findings in this study indicate that osmotic gradient between apical and basal sides is involved in the acute regulation of the cation selective property of claudin-2 channels.

Effects of Osmotic Changes on Measuring Relative Blood Volume

Recording the relative blood volume is a standard feature of modern dialysis devices. Three different measurement systems are incorporated in currently available dialysis machines. The Gambro-Hospal group and Nikkiso feature blood volume monitors based on different optical methods. The Fresenius Medical Care machines perform blood volume monitoring with an ultrasonic method. On grounds of clinical evidence suggesting a malfunction of the optical methods in the presence of sodium changes, we compared these three systems. Under the tested conditions, both optical systems show opposite and nonplausible courses of blood volume changes. The ultrasonic system seems to be less susceptible to osmotic changes.

Mechanosensitive signalling in fish gill and other ion transporting epithelia

Epithelia involved in vectorial salt transport respond to apical and basolateral changes in osmotic activity by moderating the transmural solute transport rate simultaneously with underlying volume regulatory mechanisms involved in regulatory volume increase (RVI) and decrease (RVD). This review examines rapid osmotic responses in salt secreting epithelia of marine and euryhaline teleost fish, with inclusion of recent results from other ion transporting epithelia that also respond rapidly to osmotic shock. Mitochondrion-rich chloride secreting cells of marine teleost fish gills and skin, when exposed to hypertonic shock, activate NaCl secretion via phosphorylation of Na(+), K(+), 2Cl(-) cotransporter (NKCC1) in the basolateral membrane and activation of anion channels in the apical membrane. Conversely, NaCl secretion is inhibited when chloride secreting cells are swollen osmotically. Mammalian airway epithelial cells also possess NKCC1 basally and apical anion channels [Cystic Fibrosis Transmembrane conductance Regulator (CFTR)]; with hypotonic shock, this epithelium releases ATP and NaCl secretion is stimulated via purinergic receptors, while hypertonic shock inhibits Na(+) uptake. In the eye, the ciliary epithelium activates Cl(-) channels in response to hypotonic shock as RVD, an effect that modulates transepithelial fluid transport rates. In the renal A6 cell line, K(+) and Cl(-) effluxes activate during RVD and RVI Na(+) transepithelial absorption. A common theme in these systems is ATP release in hypotonic shock with subsequent RVD-effective mechanisms such as NKCC1 inhibition and K(+) and Cl(-) efflux, but there are different effects of osmotic changes on transepithelial transport, apparently depending on the role of the epithelial system.

Hypotonic stress influence the membrane potential and alter the proliferation of keratinocytes in vitro

Keratinocyte proliferation and differentiation is strongly influenced by mechanical forces. We investigated the effect of osmotic changes in the development of HaCaT cells in culture using intracellular calcium measurements, electrophysiological recordings and molecular biology techniques. The application of hypotonic stress (174 mOsmol/l) caused a sustained hyperpolarization of HaCaT cells from a resting potential of -27 +/- 4 to -51 +/- 9 mV. This change was partially reversible. The surface membrane channels involved in the hyperpolarization were identified as chloride channels due to the lack of response in the absence of the anion. Cells responded with an elevation of intracellular calcium concentration to hypotonic stress, which critically depended on external calcium. The presence of phorbol-12-myristate-13-acetate in the culture medium for 12 h augmented the subsequent response to hypotonic stress. A sudden switch from iso- to hypotonic solution increased cell proliferation and suppressed the production of involucrin, filaggrin and transglutaminase, markers of keratinocyte differentiation. It is concluded that sudden mechanical forces increase the proliferation of keratinocytes through alterations in their membrane potential and intracellular calcium concentration. These changes together with additional modifications in channel expression and intracellular signalling mechanisms could underlie the increased proliferation of keratinocytes in hyperproliferative skin diseases.

Effects of osmotic changes on the chemoreceptor cell of rat carotid body.

The carotid body plays a crucial role in cardiorespiratory regulation. In the present study we investigated the effect of osmotic changes on cytoplasmic calcium concentration ([Ca(2+)](c)) and pH (pH(i)) of isolated chemoreceptor cells of the rat carotid body. In CO(2)/HCO(3)(-)-buffered medium, reduction of osmolality from the control level of 300 mosmol kg(-1) to 250-285 mosmol kg(-1) resulted in a rise in [Ca(2+)](c), as measured with Indo-1, whereas elevation of osmolality to 350 mosmol kg(-1) had no effect. The Ca(2+) response required extracellular Ca(2+) and was reduced by application of the L-type Ca(2+) channel antagonist nifedipine (10 microM). The hyposmosis-induced Ca(2+) response could be prevented by application of niflumic acid (300 microM), an inhibitor of the swelling-activated Cl(-) channel. In whole-cell patch-clamp experiments niflumic acid abolished the swelling-activated Cl(-) current but only slightly depressed the Ca(2+) current. The inhibition of Ca(2+) current by niflumic acid does not account for its action in preventing of hyposmosis-induced Ca(2+) response, which seems to be initiated by Cl(-)-mediated depolarisation. Withdrawal of CO(2)/HCO(3)(-) also prevented the Ca(2+) response. Reduction of the osmotic concentration by 50 mosmol kg(-1) induced a small but sustained decrease in pH(i), while elevation by 50 mosmol kg(-1) had an inverse effect, as measured fluorimetrically with carboxy SNARF-1. Our conclusion is that in the rat chemoreceptor cell the activation of Cl(-) channels, e.g. by hyposmotic challenge, induces depolarisation, which, in turn, activates voltage-gated Ca(2+) channels.

Effect of osmolarity on in vitro responses of winter flounder (Pleuronectes americanus) melanophores

No information is available on the effects of osmotic changes on winter flounder (Pleuronectes americanus) neurally regulated melanosome-aggregating responses within dermal or epidermal melanophores. The Na+ composition of balanced salt solution and the Na+ and K+ composition of K+-rich melanosome-aggregating fluid were varied to manipulate osmolarity in vitro to determine their effect on melanosome aggregation. It is evident that without previous acclimation the in vitro neuromelanophore system can tolerate a wide range of salinities equivalent to seasonal high and low levels of plasmatic osmolarity with little effect on responsiveness. In addition winter flounder neuromelanophore preparations can display attenuated responsiveness when molarities have been changed by up to 50% and without indications of cellular lysis in hypotonic media.

Effect of osmolarity on aldosterone production by rat adrenal glomerulosa cells.

The effect of osmotic changes on aldosterone production, [Ca2+]i and voltage-gated Ca2+ currents, was studied in cultured rat glomerulosa cells. Alteration of osmolarity by sucrose addition in the 250-330 mosM range did not influence aldosterone production per se, but it substantially affected K+-stimulated aldosterone production. Hyposmosis markedly increased the hormone response evoked by raising [K+] from 3.6 to 5 mM, whereas hyperosmosis had a mild decreasing effect. Cytoplasmic [Ca2+]i, measured in single glomerulosa cells, did not show detectable change in response to either hyposmotic or hyperosmotic exposure, but the [Ca2+]i signal evoked by elevation of [K+] to 5 mM was augmented in hyposmotic solution. The osmosensitivity of the transient (T)-type and long-lasting (L)-type voltage-gated Ca2+ currents was studied using the nystatin-perforated voltage-clamp technique. Lowering osmolarity to 250 mosM significantly increased the amplitude of the T-type current, and it had a transient augmenting effect on L-type current amplitude. Hyperosmotic solution (330 mosM) reduced L-type current amplitude but did not evoke significant change in T-type current. These results indicate that the responsiveness of rat glomerulosa cells to physiological elevation of [K+] is remarkably influenced by changes in osmolarity by means of modulating the function of voltage-gated Ca2+ channels.

Effects of Osmotic Changes in Extracellular Solution on Electrical Activity of Mouse Pancreatic B-Cells

The influence of changes in the osmolarity of the extracellular solution on electrical activity of mouse pancreatic B-cells was studied with intracellular microelectrodes. In the presence of 15 mmol/l glucose the membrane potential of B-cells oscillates. A reduction of the osmolarity by 40 mosmol/l caused a small temporary hyperpolarization in six out of eight cells. After 2 to 3 min electrical activity was increased in all cells. However, this effect was also transient. 5 to 8 min after onset of exposure to hypotonic solution the cells repolarized again and electrical activity decreased. Increasing the osmolarity of the extracellular solution by 40 mosmol/l led to a sustained and reversible depolarization of the membrane potential. However, the electrical activity was transiently suppressed. The changes in electrical activity observed in hypotonic solution might explain the previously described transient rise in insulin secretion provoked by osmotic cell swelling.

Osmotic shock of fertilized mouse ova.

The effect of osmotic changes on fertilized mouse ova was studied by measuring their survival, defined as development into hatching blastocysts, after exposure to various concentrations of ethanediol (ethylene glycol). In addition, a Boyle-van't Hoff plot was derived from exposing ova to hypotonic and hypertonic solutions ranging from 0.1 to 2.8 osmol. Volume of ova was inversely proportional to osmolality over this range. Extrapolation of this relationship yielded a nonosmotic volume of the ova of 22.5%. Eighty-five per cent or more of the ova survived exposure to this wide range of concentrations and developed into blastocysts. The rate of development of ova exposed to anisotonic solutions was the same as that of controls. Ova underwent osmotic shock when abruptly diluted out of concentrated solutions of ethanediol with an isotonic solution. Their survival was highly dependent on the ethanediol concentration with which they had equilibrated before dilution, and the manner, rate and temperature of dilution. The longer the exposure to ethanediol the greater was the sensitivity of the ova to osmotic shock, reflecting permeation of ethanediol into the ova. Osmotic shock could be alleviated by dilution at a high temperature, and prevented by the use of sucrose as an osmotic buffer at 37 degrees C. Identification of the variables that influence osmotic shock of ova will be helpful in the systematic study of their cryopreservation.

Plasticity in the in vitro neurohypophysis: Effects of osmotic changes on pituicytes

The ultrastructure of rat neurohypophyses incubated in vitro was studied to investigate secretion-related changes that may be intrinsic to the isolated neurohypophysis and to establish the morphological integrity of this preparation. Neurohypophyses were incubated for 2 h in an in vitro chamber in medium of low (290 mosM/kg), normal (310 mosM/kg), or high (340mosM/kg) osmolality. Subsequent morphometric analyses at the ultrastructural level revealed that the number of axons completely enclosed by pituicyte cytoplasm was inversely related and the amount of neuro-vascular contact was directly related to the osmolality of the medium. These results mimic those found in preparations from in vivo experiments with hydrated and dehydrated rats. The number of pituicyte liposomes did not vary consistently with osmolality. We conclude that: (1) dynamic interactions between pituicytes and neurosecretory axons may be stimulated, at least in part, by the immediately surrounding milieu; (2) pituicytes may have an active role as modulators of hormone release; and (3) the in vitro neurohypophysis provides a suitable model to study events intrinsic to this area.

Effects of osmotic changes and neurosecretory extracts on kidney ultrastructure in the freshwater pulmonate Helisoma

The ultrastructure of the heart and kidney, and the effects of media of different osmotic concentrations and of nervous tissue extracts, have been investigated in Helisoma duryi and H. trivolvis. The auricle and ventricle walls do not appear to be possible sites for urine formation. In the kidney sac, ferritin and carbon particles are retained by the basement membrane of the epithelium, whereas horseradish peroxidase passes through the basement membrane into the intercellular spaces 10 min after injection. Epithelial cells have deep basal membrane infoldings. Intercellular spaces and spaces in the infoldings are wide in snails kept in distilled water but narrow in snails kept in isosmotic saline. When kidney sacs from saline-acclimated snails were treated in vitro with visceral ganglion extract from snails kept in distilled water these spaces rapidly expanded. Visceral ganglion extract from snails kept in saline, or extracts of other ganglia, had no effect. It is suggested that urine formation occurs in the kidney sac, and that a factor (probably neurosecretory) from the visceral ganglion may act on kidney sac epithelium to alter the rate of filtration and fluid (prourine) transport.

EFFECTS OF OSMOTIC CHANGES ON WATER AND ELECTROLYTES IN NERVOUS TISSUE.

The Journal of PhysiologyVolume 177, Issue 2 p. 246-262 ArticleFree Access Effects of osmotic changes on water and electrolytes in nervous tissue* A. Ames III, A. Ames IIISearch for more papers by this authorJ. B. Isom, J. B. IsomSearch for more papers by this authorFrances B. Nesbett, Frances B. NesbettSearch for more papers by this author A. Ames III, A. Ames IIISearch for more papers by this authorJ. B. Isom, J. B. IsomSearch for more papers by this authorFrances B. Nesbett, Frances B. NesbettSearch for more papers by this author First published: 01 March 1965 https://doi.org/10.1113/jphysiol.1965.sp007590Citations: 17 * This investigation was supported in part by research grants (M-6209, MH-K3-3769) from the National Institute of Mental Health. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume177, Issue2March 1, 1965Pages 246-262 RelatedInformation

ASPECTS OF MARINE DINOFLAGELLATE NUTRITION MEASURED BY C14 ASSIMILATION.

SYNOPSIS. A rapid and sensitive method for determining the nutritional requirements of marine phytoflagellates in axenic culture is described. C14 assimilation (added as NaHC14O3) was used as a measure of response to minimal concentrations of nutrients and for studying the effects of osmotic changes on cells. The results demonstrated that Glenodinium halli Freudenthal & Lee required B12, was stimulated by thiamine, and that it is a euryhaline species. The applications and advantages of this technique in nutritional studies and bioassays are discussed.

The effect of osmotic changes in the small intestine upon gastric emptying in man

For the same reasons that we concluded the pyloric action was motivated locally through duodenal stimulation by chemical action, we conclude that this same mechanism is influenced by physical stimuli as represented by changes in osmotic pressure away from isotonicity. Gastric emptying time alone cannot be used as an index of pyloric function when considering osmotic tension of agents given by mouth because of the migration of fluid which takes place through the stomach wall when the test meals are not isotonic.