Absolute Permeability
Mostrando 13-24 de 28 artigos, teses e dissertações.
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13. Determination of ionic permeability coefficients of the plasma membrane of Xenopus laevis oocytes under voltage clamp.
1. A method of estimating absolute ionic permeability coefficients which does not depend on the use of impermeant substitutes is reported. 2. The method is based on a pump leak model of the Xenopus laevis oocyte membrane. The procedure consists of measuring, in the same experiment, the pump current and the currents generated under voltage clamp by the partia
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14. The effect of estrogen on bile formation in the rat
Female rats given large doses of estrone developed increased permeability of the biliary tree as determined by an increase in the biliary clearances of sucrose and mannitol. Spontaneous bile flow and the choleretic response to dehydrocholate declined. Estrone reduced the clearance of sulfobromophthalein (BSP) at low plasma concentrations as well as the absol
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15. Apical membrane permeability and kinetic properties of the sodium pump in rabbit urinary bladder.
Previous studies have shown that aldosterone stimulates the rate of Na+ transport across the rabbit urinary bladder epithelium by increasing the apical membrane permeability to Na+. Paradoxically, ion-sensitive and conventional micro-electrode measurements demonstrated that intracellular Na+ activity aiNa+ was essentially unchanged by aldosterone, i.e. aiNa+
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16. Paracellular Cl- permeability is regulated by WNK4 kinase: Insight into normal physiology and hypertension
Paracellular ion flux across epithelia occurs through selective and regulated pores in tight junctions; this process is poorly understood. Mutations in the kinase WNK4 cause pseudohypoaldosteronism type II (PHAII), a disease featuring hypertension and hyperkalemia. Whereas WNK4 is known to regulate several transcellular transporters and channels involved in
National Academy of Sciences.
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17. Biochemical and physiological changes induced by anthrax lethal toxin in J774 macrophage-like cells.
Experiments were performed to probe the mechanism by which Bacillus anthracis Lethal Toxin (LeTx) causes lysis of J774 macrophage-like cells. After incubation of cells with saturating concentrations of the toxin, two categories of effects were found, which were distinguishable on the basis of chronology, Ca(2+)-dependence, and sensitivity to osmolarity. The
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18. Glomerular Hemodynamics in Rats with Chronic Sodium Depletion: EFFECT OF SARALASIN
In chronic sodium depletion the glomerular filtration rate may be reduced, and alterations in proximal tubular function may contribute to the maintenance of antinatriuresis. Measurements were made by micropuncture technique in superficial nephrons of the Munich-Wistar rat of (a) the determinants of glomerular filtration rate, (b) peritubular capillary hydros
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19. Leaf Water Stress in Engelmann Spruce: Influence of the Root and Shoot Environments 1
The response of xylem pressure potential of Engelmann spruce (Picea engelmannii Engelm.) to environmental factors was studied in the natural subalpine environment. Data were analyzed in the context of a leaf water potential model based upon the van den Honert model for water transport through the soil-plant-atmosphere continuum. At soil temperatures of 10 to
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20. Transbuccal Delivery of 5-Fluorouracil: Permeation Enhancement and Pharmacokinetic Study
The purpose of this study was to determine the effect of permeation enhancers on the transbuccal delivery of 5-fluorouracil (FU). The effect of permeation enhancers on in vitro buccal permeability was assessed using sodium deoxycholate (SDC), sodium dodecyl sulphate (SDS), sodium tauroglycocholate (STGC), and oleic acid and their concentrations for absorptio
Springer US.
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21. Crosslinking the active site of sarcoplasmic reticulum Ca(2+)-ATPase completely blocks Ca2+ release to the vesicle lumen.
Intramolecular crosslinking of the active site of the sarcoplasmic reticulum Ca(2+)-ATPase with glutaraldehyde results in substantial inhibition of ATPase activity and stabilization of the ADP-sensitive E1 approximately P(2Ca) intermediate (E, enzyme) with occluded Ca2+ [Ross, D. C., Davidson, G. A. & McIntosh, D. B. (1991) J. Biol. Chem. 266, 4613-4621]. We
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22. Cellular and subcellular immunolocalization of vasopressin-regulated water channel in rat kidney.
Vasopressin (antidiuretic hormone) regulates body water balance by controlling water permeability of the renal collecting ducts. The control mechanisms may involve alterations in the number or unit conductance of water channels in the apical plasma membrane of collecting-duct cells. How this occurs is unknown, but indirect evidence exists for the "shuttle" h
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23. A study of stretch-activated channels in the membrane of frog oocytes: interactions with Ca2+ ions.
1. We have carried out patch-clamp measurements on a cationic channel in the plasma membrane of the frog oocyte, which can be specifically activated by membrane stretch. The kinetics of this channel also display a distinct dependence upon membrane potential, the probability of the channel being open increasing with membrane depolarization. 2. When the patch-
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24. Effect of ketoconazole on lethal action of amphotericin B on Leishmania mexicana promastigotes.
The effect of ergosterol depletion by ketoconazole on the leishmanicidal activity of the pore-forming antibiotic amphotericin B (AmB) was investigated. Leishmania mexicana promastigotes were lysed within minutes by the addition of micromolar concentrations of AmB (0.5 microM) but became insensitive to AmB after growth in the presence of ketoconazole (0.25 mi