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Results for “Cell Membrane Permeability”

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PubMed1975

[Change in cell membrane permeability, and composition and properties of hexokinase during induced carcinogenesis].

The isoenzyme hexokinase (HK) spectrum from normal rat large intestinal mucosa consisted of 3 isoenzymes. In tumours of this localization induced by 1,2-dimethylhydrazine there proved to be a lack or marked decrease in the most rapid anodic isoenzyme. Only one HK isoenzyme was found in the metastases. Km (glucose) for tumour HK was 2--3 times lower than for normal intestinal HK; the HK activity was detected in the serum from the 1st month of the carcinogenic administration, and by the 5th month it was found in 80% of the tumour-bearing animals. No serum HK activity was ever found in control rats.

Adenocarcinoma↗
PubMedDate not supplied

[Effect of triterpene glycosides and polyene antibiotics on cell membrane permeability for K+ ions and UV-absorbing substances].

The effect of triterpene glycosides (cauloside C from Caulophyllum robustum, theasaponine from Thea sinensis, cucumarioside G from Cucumaria fraudatrix stichoposide A from Stichopus japonicus S., holothurines A and B from Holothuria mexicana, holothurine C from Bohadschia sp.) on the membrane permeability for K+ ions and UV-absorbing substances was compared with that of polyene antibiotics, viz., amphotericine B and nystatine. As a biological model fertilized eggs of sea urchin Strongylocentrotus nudus and yeast Saccharomyces carlsbergensis were used. In the sea urchin study most triterpene glycosides in low concentrations induced the outflux of K+ and in hgih concentrations that of both K+ and UV-absorbing agents. In the yeast study triterpene glycosides at identical doses induced the outflux of both K+ and UV-absorbing agents. The membranotropic effect of triterpene glycosides depended on the medium temperature and the biological system used.

Anti-Bacterial Agents↗
PubMed1968

Independent action of antidiuretic hormone, theophylline and cyclic 3',5'-adenosine monophosphate on cell membrane permeability in frog skin.

1. The effects of antidiuretic hormone (ADH), theophylline and cyclic 3',5'-adenosine monophosphate (AMP) on membrane potentials in frog skin have been investigated.2. Membrane potentials across the outer and inner facing membranes were recorded in both normal and current clamped skins. In the latter condition active transport of sodium had been abolished by ouabain or metabolic inhibitors, but ionic gradients were maintained by passing current through the skin from the inside.3. ADH increases the potential across the outer facing membranes and reduces the skin resistance. The results are consistent with ADH causing an increase in permeability of the outer facing membranes to sodium ions.4. Theophylline reduces the skin potential by reducing specifically the potential across the outer facing membranes. At the same time the skin resistance is reduced. Theophylline acts by increasing the permeability of the outer facing membranes to chloride ions.5. Cyclic 3',5'-AMP causes a biphasic potential change accompanied by an increase in skin resistance.6. Metabolic inhibitors block the response of the skin to ADH but not to theophylline.7. Separate explanations for the increase in sodium transport by ADH, theophylline and cyclic 3',5'-AMP are discussed. It is not necessary to involve cyclic AMP in order to explain the effects of either ADH or theophylline.

Adenine Nucleotides↗
PubMed1968

Effect of Infection by Hypomyces solani f. sp. Cucurbitac on Apparent Free Space, Cell Membrane Permeability, and Respiration of Squash Hypocotyls.

Initial symptoms and increases in respiration, apparent free space, and rate of leakage of amino acids occurred concomitantly in squash (Cucurbita maxima Dcne) hypocotyls infected by Hypomyces solani f. sp. cucurbitae Snyd. and Hans. Young, rapidly expanding lesions had greater respiratory rates and apparent free space than comparable tissues from healthy plants.Hypocotyl tissues above (1-45 mm) lesions possessed greater endogenous respiratory rates (2-3 times) and lower respiratory quotients than similar tissues from healthy plants. But no differences were found in membrane permeability to nonelectrolytes and water and in apparent free space between cells above lesions and healthy hypocotyls.Host cells contiguous to fungal hyphae at lesion margins were completely permeable to solutes and failed to accumulate neutral red or exhibit cyclosis.

Journal Article↗
PubMed1989

[Ultrastructure of myocardium and permeability of cell membrane in early severe burns of mice].

Using lanthanum tracer, we investigated the ultrastructure and the cell membrane permeability of mouse cardiac muscles in the early stage of severe burns. The main pathological changes included loosening and flocculation of myofibrils, local dilation of intercalated discs, increase and degeneration of mitochondria, and edema of interstitium. Lanthanum tracer located inside the myocardial cells, which indicated that the permeability of cell membrane was increased. The present study suggested that the onset of abnormal cardiac rate and arrhythmia in early stage of severe burns probably related to these pathological changes.

Animals↗
PubMed1972

Changes in Cell Membrane Permeability in Sunflower Hypocotyls Infected with Sclerotinia sclerotiorum.

Influx and efflux of water and urea and electrolyte leakage are less for sunflower (Helianthus annuus) hypocotyl sections above lesions caused by Sclerotinia sclerotiorum than for those from healthy plants. Urea uptake by sections above lesions is reduced (celery, squash, and tomato) or unchanged (bean) in other hosts after Sclerotinia infection. Efflux of urea from sunflower hypocotyls is biphasic, suggesting diffusion in series from two cellular compartments (cytoplasm and vacuole). Efflux during the fast phase was 7 to 20 times greater than that during the slow phase. No difference was noted in urea efflux from healthy and diseased tissues during the slow phase. However, efflux during the fast phase from diseased tissues was slower than from healthy tissues, suggesting that the increased resistance to diffusion of urea in host cells above lesions resides in the plasmalemma. Water movement across cell membranes of healthy and diseased sunflower hypocotyls was reduced when tissues were treated with p-hydroxymercuribenzoate.

Journal Article↗
PubMed1993

Surface binding and uptake of cadmium (Cd2+) by LLC-PK1 cells on permeable membrane supports.

Recent studies have shown that Cd2+ has relatively specific damaging effects on cell-cell junctions in the renal epithelial cell line, LLC-PK1. The objective of the present studies was to examine the surface binding and uptake of Cd2+ by LLC-PK1 cells in relation to the disruption of cell-cell junctions. LLC-PK1 cells on Falcon Cell Culture Inserts were exposed to CdCl2 containing trace amounts of 109Cd2+ from either the apical or the basolateral compartments, and the accumulation of 109Cd2+ was monitored for up to 8 h. The integrity of cell-cell junctions was assessed by monitoring the transepithelial electrical resistance. The results showed that the cells accumulated 3-4 times more Cd2+ from the basolateral compartment than from the apical compartment. The accumulation of Cd2+ from the basolateral compartment occurred in two phases: a rapid, exponential phase that occurred in 1-2 h and coincided with a decrease in transepithelial resistance, and a slower, linear phase that continued for 6-8 h. The Cd2+ that accumulated during the rapid phase was easily removed by washing the cells in EGTA, indicating that most of it was bound to sites on the cell surface. By contrast, most of the Cd2+ that accumulated during the slower phase could not be removed by EGTA, indicating that it had been taken up by the cells. Additional studies showed that the rapid phase of Cd2+ accumulation was enhanced when Ca2+ was present at low concentrations (0.1 mM), and was greatly reduced when Ca2+ was present at high concentrations (10 mM).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2006

Intact plant MRI for the study of cell water relations, membrane permeability, cell-to-cell and long distance water transport.

Water content and hydraulic conductivity, including transport within cells, over membranes, cell-to-cell, and long-distance xylem and phloem transport, are strongly affected by plant water stress. By being able to measure these transport processes non-invasely in the intact plant situation in relation to the plant (cell) water balance, it will be possible explicitly or implicitly to examine many aspects of plant function, plant performance, and stress responses. Nuclear magnetic resonance imaging (MRI) techniques are now available that allow studying plant hydraulics on different length scales within intact plants. The information within MRI images can be manipulated in such a way that cell compartment size, water membrane permeability, water cell-to-cell transport, and xylem and phloem flow hydraulics are obtained in addition to anatomical information. These techniques are non-destructive and non-invasive and can be used to study the dynamics of plant water relations and water transport, for example, as a function of environmental (stress) conditions. An overview of NMR and MRI methods to measure such information is presented and hardware solutions for minimal invasive intact plant MRI are discussed.

Biological Transport↗
PubMed2006

Vibrating microbubbles poking individual cells: drug transfer into cells via sonoporation.

Ultrasound contrast microbubbles have the ability to enhance endothelial cell permeability and thus may be used as a new way to deliver drugs. It facilitates the transfer of extracellular molecules into cells activated through ultrasound driven microbubbles. The present study is designed to correlate the relationship between microbubble induced cell deformation and enhanced cell membrane permeability. Propidium iodide (PI) was used as a membrane integrity probe. Using high-speed imaging of vibrating microbubbles against endothelial cells and imaging transport of PI into these cells showed a direct correlation between cell deformation and resulting cell membrane permeability. The membrane permeabilization lasted for a short period without affecting endothelial cells viability. We identified that microbubbles are crucial to enhance transient cell membrane permeability. Thus, permeability of individual cells is increased. The roles of ultrasound contrast microbubbles as the trigger for improved drug efficacy are discussed.

Animals↗
PubMed1984

[Increase in the permeability of the lymphocyte plasma membrane for uni- and bivalent cations and low-molecular metabolites following exposure to mitogenic polyanions].

The paper is concerned with a study of the molecular mechanisms responsible for activation of B lymphocyte division by polyanions, polyacrylic acid (PAA) and dextran sulfate (DS). The mitogenic doses of PAA and DS were discovered to provoke an early increase in lymphocyte plasma membrane permeability. The cell membrane permeability for K+, Ca2+ and for labeled thymidine and uridine was measured in murine spleen cultures in vitro The K+ outflow from the cells was recorded according to variation in K+ concentration in the extracellular medium with the aid of a selective valinomycin electrode. The intensity of cell penetration by exogenous 45Ca, 3H-uridine or 3H-thymidine was determined by radioindicator analysis of the cytoplasma isotope pool. One to 2 min after adding the mitogenic doses of PAA or DS, the K+ outflow from lymphocytes markedly increased. It has been proved that this effect is not connected with inhibition of Na+, K+-ATPase of the plasma membrane. The increased membrane permeability for 45Ca and 3H-uridine was recorded 30-40 min after lymphocyte activation with the polyanion, that for 3H-thymidine was seen later (after 4-6 h). It is assumed that the differences between the time of recording high accumulation in the cytoplasm of 45Ca, 3H-uridine and 3H-thymidine and the time of recording high outflow of K+ from lymphocytes are determined by the differences in the sensitivity of the methods applied.

Acrylic Resins↗
PubMed2000

Anion permeability and erythrocyte swelling.

Permeability of cell membranes to cations may increase as a result of membrane oxidation or in certain pathologies. We studied the effects of nonselective increases in cell membrane permeability to univalent cations on the volume of erythrocytes incubated in phosphate-buffered saline (PBS) using amphotericin B (5-10 mg/l suspension) or gramicidin D (10-100 microg/l suspension) as the membrane permeabilizing agents. Both antibiotics caused K+ to leak, Na+ to accumulate intracellularly, and cell volume to increase. The interval needed to reach the equilibrium between the intracellular and extracellular ion concentrations ranged from 30 min to several hours, depending on the antibiotic concentration. In spite of a rapid disappearance of cation transmembrane gradients, cell volume increased relatively slow. Even 24 h after the membrane permeability was changed, the volume of most erythrocytes did not increase to the lytic values (about 1.6 times the normal volume). The slow increase in erythrocyte volume was accounted for by slow changes in the transmembrane Cl- gradient. 4,4'-Diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS), a specific inhibitor of anion transport, while producing no effect on the transmembrane Na+ and K+ fluxes induced by the antibiotics, significantly inhibited the decrease in the transmembrane Cl- gradient and the increase in erythrocyte volume. Analysis of these data by means of mathematical modeling showed that it failed to satisfactorily describe the experimental kinetics of erythrocyte swelling in response to increases in the membrane permeability to univalent cations if its permeability to Cl was set to be constant. The satisfactory description of this kinetics could be achieved by assuming that the membrane permeability to anions decreased with increasing erythrocyte volume. The results obtained demonstrate that transmembrane anion transport may be considered to be a component of the mechanism responsible for the erythrocyte volume stabilization, because a significant decrease in the swelling rate allows the erythrocytes with damaged membranes to activate a relatively slow (metabolic) mechanisms of cell volume stabilization and/or repair their damaged membranes.

Amphotericin B↗
PubMed1987

Cell membrane water permeability of rabbit cortical collecting duct.

The water permeability (Posm) of the cell membranes of isolated perfused rabbit cortical collecting ducts was measured by quantitative light microscopy. Water permeability of the basolateral membrane, corrected for surface area, was 66 microns X sec-1 for principal cells and 62.3 microns X sec-1 for intercalated cells. Apical membrane Posm values corrected for surface area, were 19.2 and 25 microns X sec-1 for principal and intercalated cells, respectively, in the absence of antidiuretic hormone (ADH). Principal and intercalated cells both responded to ADH by increasing Posm of their apical membranes to 92.2 and 86.2 microns X sec-1, respectively. The ratio of the total basolateral cell membrane osmotic water permeability to that of the apical cell membrane was approximately 27:1 in the absence of ADH and approximately 7:1 in the presence of the hormone for both cell types. This asymmetry in water permeability is most likely due to the fact that basolateral membrane surface area is at least 7 to 8 times greater than that of the apical membrane. Both cell types exhibited volume regulatory decrease when exposed to dilute serosal bathing solutions. Upon exposure to a hyperosmotic serosal bath (390 mosM), principal cells did not volume regulate while two physiologically distinct groups of intercalated cells were observed. One group of intercalated cells failed to volume regulate; the second group showed almost complete volume regulatory increase behavior.

Animals↗