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Results for “Cell Membrane Permeability”

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At least 19 recordsLinked to original sources
PubMed1976

[Radiosensitive mutants of Escherichia coli with disrupted cell membrane permeability].

Membrane proteins and cell permeability of Escherichia coli B/r and different substrains of B/r containing mutations of loci uvrB, exrA, lon and suppressors of that mutations were studied. Membrane proteins were found to be modified only in E. coli B/r exrA. The content of 40 000--70 000 D polypeptides was increased and the content of 80 000--100 000 D polypeptides was decreased. Alteration of membrane proteins in E. coli B/r exrA was associated with the impaired permeability of cell membrane.

Cell Membrane Permeability↗
PubMed1978

Increased cell membrane permeability to Na+ and K+ induced by thyroid hormone in rat skeletal muscle.

Thyroid hormone (T3) increased Na+ dependent respiration accompanied by an increase in NaK-ATPase activity. Administration of T3 increased intracellular K+ concentration and Na/K ratio in thyroidectomized rats, and the Na+ efflux rate constant incubated in oxygenized Na+, K+-Ringers in euthyroid rats. However, the magnitude of the changes in intracellular K+ concentration was modest or invisible in comparison to the changes in QO2(t) and NaK-ATPase activity. The Na+ and K+ efflux rate constants in K+-free +ouabain Ringers were increased by T3 in both thyroidectomized and euthyroid rats. Thus, thyroid hormone stimulates not only Na pump but also the permeability of cell membrane to Na+ and K+. The both effects might contribute to the thyroid thermogenesis.

Adenosine Triphosphatases↗
PubMed1978

Changes in the lipid composition of ripening banana fruits and evidence for an associated increase in cell membrane permeability.

The content of total lipid in banana fruit pulp tissue remained constant during the climacteric rise induced by applied ethylene. The relative proportions of neutral lipid, glycolipid and phospholipid did not change. However, the fatty acid composition of the lipid did change during ripening. This change was confined largely to the phospholipid fraction, in which there was an increase in the proportion of linolenic acid and a decrease in the proportion of linoleic acid. The net result was an increase in total unsaturation of the fatty acids in the phospholipid fraction. Measurements of spin label motion in liposomes prepared from banana phospholipids showed that the motion and fluidity of bilayer lipids increased during ripening of the fruit from which the liposomes were prepared, probably as a result of increased lipid unsaturation during ripening. Since increases in membrane fluidity are accompanied by increases in the passive permeability to small molecules in a number of membrane systems, it is suggested that the increased leakage which has been previously demonstrated in ripening banana fruit tissue is due to increases in the permeability of at least some cell membranes.

Cell Membrane Permeability↗
PubMed1978

Cell membrane ionic permeability, calcium ion, mitochondria, and carcinogenesis.

The interrelations between changes in cell membrane permeability, increase of intracellular concentration of calcium ion and alterations of the bioenergetic and genetic mechanisms of the mitochondria are formalized in a hypothesis of carcinogenesis. It seems very likely that changes in the permeability of the cell membrane induced by the carcinogen are responsible for increased intracellular accumulation of Ca2+. This phenomenon produces mitochondrial damage associated with permanent modifications of the structural and functional characteristics of the cell membranes as well as of the genetic mechanisms controlling cell division.

Biological Transport↗
PubMed1977

The influence of antibiotics WR 142 on permeability of cell membranes.

The influence of antibiotics WR 142 (fractions I and II and Wr 142 FPG) on transport across cell membranes of B. subtilis and C. albicans was studied. Antibiotics Wr 142 did not increase permeability of cell membranes as 86Rb was not exchanged by other monovalent ions in the presence of the antibiotic preparations. Temperature, ionic strength and pH had no significant influence on the action of these antibiotics on the cell membranes. Antibiotics Wr 142 do not form lipid-soluble complexes with alkali metal ions, and therefore do not transport these ions, in contrast to the ionophoric antibiotics. No effect of antibiotics Wr 142 on the stucture of the cell membrane depriving it of its selective function as an osmotic barrier was observed.

Anti-Bacterial Agents↗
PubMed1979

Permeability of the cell-to-cell membrane channels in mammalian cell juncton.

The channels in the junctions of various mammalian cell types--primary cultures and lines--were probed with a series of linear fluorescent amino acid and peptide molecules of different size and charge. Permeability is limited by probe size and electronegativity, these two factors apparently being related reciprocally. In respect to both factors, mammalian junctional channels are more restrictive than insect channels; hence the mammalian channels are narrower, more polar, or both. The channels of the various mammalian cell types differed slightly from each other; in some types the serum of the culture medium affected the channel permeability.

Animals↗
PubMed1977

Permeability of membrane to potassium in hypochromic red cells with different specific density.

In hypochromic anaemias (heterozygous beta-thalassaemia and iron deficiency anaemia) ligher red cells lose more K+ than heavier ones, following incubation at 37 degrees C for 24 h. Both in the light and heavy fractions two subpopulations of cells with different permeability to K+ can be separated by a new centrifugation after incubation. On the basis of the results, a relationship between K+ permeability and probability of survival in hypochromic cells is suggested.

Anemia, Hypochromic↗
PubMed1978

The role of various prostaglandins on the correlation between permeability to albumin and cAMP levels in the isolated mesentery.

Prostaglandins (PG) have been shown to raise the level of cyclic AMP (cAMP) in various tissues, and to increase permeability. Whether both events are linked, is at present a matter of speculation. We have investigated the effects of PGE1, E2, A1, A2, F1alpha and F2alpha on an isolated rat mesentery placed in a diffusion cell (surface area : 2 sq.cm). The PGs (5 microgram/ml) increased the passage of (I 125) - Albumin across the mesentery. In other experiments, diks of rat mesentery (surface area : 2 sq.cm) have been incubated in assay tubes, and cAMP levels measured by a binding protein assay. We have observed an excellent correlation between increases in permeability and cAMP levels (r=0.961). In order of increasing potency on both parameters, the PGs may be classified as follows : PGF, PGA and PGE. In the rat mesentery, under the influence of prostaglandins, increases in permeability and in cAMP levels are apparently connected.

Albumins↗
PubMed1978

Effect of human leukocyte interferon on the permeability of the cytoplasma membrane of cultured cells.

The effect of human leukocyte interferon on the cytoplasma membrane of cultured homologous cells has been investigated. U-amnion cells were labelled with (1-14C) alpha-aminoisobutyric acid (AIB), a low-molecular-weight non-metabolizable amino acid. Following uptake, the AIB is released spontaneously from the cells. Treatment of cells with interferon reduced the AIB release. This effect was dosedependent, was neutralized by anti-interferon serum and was strongly reduced by trypsin treatment.

Aminoisobutyric Acids↗
PubMedDate not supplied

Mitochondrial calcium during liver carcinogenesis due to thioacetamide and 4-dimethylaminoazobenzene.

In a series of experiments the prolonged feeding of rats with thioacetamide and 4-dimethylaminoazobenzene provoked an increase in mitochondrial calcium. It seems likely that this continuous mitochondrial overloading with Ca2+ is related to metabolic and functional changes of the liver cell leading to a neoplastic transformation. The drastic changes in cell membrane permeability of cholangiocarcinoma tumor cells, reflected by an increased concentration of extracellular cations (calcium and sodium), while the intracellular cations tended to decrease, indicate that the mitochondrial function of specification of cell membrane characteristics is possibly impaired by that calcification.

Acetamides↗
PubMed1978

Effects of X-rays on cell membranes. II. Changes of permeability measured by fluorescein efflux.

The effect of irradiation on the permeability of cell membranes of L-929 cells was investigated. Efflux of fluorescein, accumulated by hydrolysis of fluoresceindiacetate in the cells, was measured using flow cytometry. The changes of rate constants for the permeation of florescein through the cell membrane at different temperatures and after various X-ray doses were studied. Decreasing temperatures yielded substantially slower efflux of fluorescein. After irradiation of cells, the rate constant of fluorescein efflux increased linearly with dose; 180 Gy are required to cause an increase by a factor of 2. The results are discussed with respect to radiation damage of active and passive transport mechanisms.

Cell Membrane Permeability↗
PubMed1977

Smooth muscle cell changes of media underlying experimental arterial thrombosis.

The is much evidence that platelet thrombi release many factors which can alter endothelial permeability and may alter other cell membrane permeability. A large thrombus could also interfere with the diffusion of oxygen to the inner media. In either case injury of the medial cells may affect their ability to metabolize lipid.

Animals↗
PubMed1978

Chemically-induced cation permeability in red cell membrane vesicles. The sidedness of the response and the proteins involved.

Cation fluxes were measured in right-side-out and inside-out vesicles obtained from human red cells. Rubidium, which is spontaneously released at very slow rates, can be rapidly released from both types of vesicle by addition of valinomycin. P-Chloromercuriphenyl sulfonic acid (PCMBS) also increases the cation permeability of the vesicles with reversal to normal after addition of dithiothreitol. The effect of PCMBS is considerably larger and appears faster in the inside-out vesicles as compared to the right-side-out vesicles, the difference being greater at low temperatures. These data indicate that the SH groups responsible for the changes in cation permeability are more accessible from the inside face of the membrane. The response to PCMBS was not diminished after selective removal of extrinsic proteins by alkaline extraction, and/or after the membranes were exposed to proteolytic enzymes. The major polypeptide component remaining in vesicles after both treatments was a 17 000-dalton transmembrane fragment derived from band 3 which might, therefore, be responsible for the permeability response. Addition of Ca2+ to either right-side-out or inside-out vesicles, in the presence or absence of ionophore A23187, was without effect on monovalent cation permeability, indicating that the mechanism of Ca2+-induced K+ permeation was lost or inactivated during the preparation of the vesicles.

4-Chloromercuribenzenesulfonate↗
PubMed1979

Electrical properties of the cellular transepithelial pathway in Necturus gallbladder: III. Ionic permeability of the basolateral cell membrane.

The ionic permeability of the basolateral membrane of Necturus gallbladder epithelium was studied with intracellular microelectrode techniques. After removal of most of the subepithelial tissue (to reduce unstirred layer thickness), impalements were performed from the serosal side, and ionic substitutions were made in the serosal solution while a microelectrode was kept in a cell. Thus, it was possible to obtain continuous (and reversible) records of transepithelial and cell membrane potentials and to measure intermittently the transepithelial resistance and the ratio of cell membrane resistances. From these data and the mean value of the equivalent resistance of the cell membranes in parallel (obtained from cable analysis in a different group of tissues), absolute cell membrane and shunt resistances and equivalent electromotive forces (emfs) were calculated. From the changes of basolateral membrane emf (Eb) produced by the substitutions, the conductance (G) and permeability (P) of the membrane for K, Cl and Na were estimated. Potassium-for-sodium substitutions produced large reductions of both cell membrane potentials, of Eb, and of the resistance of the basolateral membrane (Rb), indicating high GK and PK. Chloride substitution with isethionate or sulfate resulted in smaller changes of cell membrane potentials and Eb and in no significant change of Rb, indicating small but measurable values of GCl and PCl. Sodium substitutions with N-methyl-D-glucamine (NMDG) resulted in cell potential changes entirely attributable to the biionic potential produced in the shunt pathway (PNa greater than PNMDG), and in no significant changes of Rb or Eb, indicating that GNa and PNa are undetectable. The question of the mechanism of Cl transport across the basolateral membrane was addressed by comparing the mean rate of transepithelial Cl transport : formula, see text: and the predicted passive Cl flux across the basolateral membrane (from the membrane Cl conductance, potential, and Cl equilibrium potential). The conclusion is that only a very small fraction of the Cl flux across the basolateral membrane can be electrodiffusional. Since the paracellular Cl conductance is also too low to account for : formula, see text:, these results suggest the presence of a neutral mechanism of Cl extrusion from the cells. This could be a NaCl pump, a downhill KCl transport mechanism, or a Cl-HCO3 exchange mechanism.

Animals↗