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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of agricultural and food chemistry 30 (1982), S. 1079-1082 
    ISSN: 1520-5118
    Source: ACS Legacy Archives
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Development genes and evolution 193 (1984), S. 252-256 
    ISSN: 1432-041X
    Keywords: Ecdysteroids ; Lepidoptera cell lines ; Morphological changes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In the continuous cell lines of the LepidopteraTrichoplusia ni (TN-368) andSpodoptera littoralis (HPB-SL-26), ecdysone and 20-hydroxyecdysone cause a series of morphological changes: some cells aggregate, elongate and extend long thin processes. The extent and rapidity of changes are dose dependent, 20-hydroxy-ecdysone being much more active then ecdysone. The continuous cell lines ofS. littoralis (UIV-SL-573) andS. frugiperda (IPLB-SF-21) were much less responsive to the presence of the ecdysteroids.
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  • 3
    ISSN: 1432-1424
    Keywords: transepithelial Na transport ; apical Na perme-ability ; Na-channel density ; oxytocin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Urinary bladders ofBufo marinus were depolarized, by raising the serosal K concentration, to facilitate voltage-clamping of the apical membrane. Passive Na transport across the apical membrane was then studied with near-instantaneous current-voltage curves obtained before and after eliciting a natriferic response with oxytocin. Fitting with the constant-field equation showed that the natriferic effect is accounted for by an increase in the apical Na permeability. It is accompanied by a small increase in cellular Na activity. Furthermore, fluctuation analysis of the amiloride-induced shot-noise component of the short-circuit current indicated that the permeability increase is not due to increased Na translocation through those Na channels which were already conducting prior to hormonal stimulation. Rather, the natriferic effects is found to be based on an increase in the population of transporting channels. It appears that, in response to the hormone, Na channels are rapidly “recruited” from a pool of electrically silent channels.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    The journal of membrane biology 62 (1981), S. 7-17 
    ISSN: 1432-1424
    Keywords: Renal transport ; proximal tubule ; selective microelectrodes ; chloride ; intracellular activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary To assess the mechanism(s) by which intraluminal chloride concentration is raised above equilibrium values, intracellular Cl− activity (α i Cl ) was studied in the proximal tubule ofNecturus kidney. Paired measurements of cell membrane PD (V BL) and Cl-selective electrode PD (V BL Cl ) were performed in single tubules, during reversible shifts of peritubular or luminal fluid composition. Steadystate α i Cl was estimated at 14.6±0.6 mmol/liter, a figure substantially higher than that predicted for passive distribution. To determine the site of the uphill Cl− transport into the cell, an inhibitor of anion transport (SITS) was added to the perfusion fluid. Introduction of SITS in peritubular perfusate decreased α i Cl , whereas addition of the drug in luminal fluid slightly increased α i Cl ; both results are consistent with basolateral membrane uphill Cl− transport from interstitium to the cell. TMA+ for Na+ substitutions in either luminal or peritubular perfusate had no effect on α i Cl . Removal of bicarbonate from peritubular fluid, at constant pH (a situation increasing HCO 3 − outflux), resulted in an increase of α i Cl , presumably related to enhanced Cl− cell influx: we infer that Cl− is exchanged against HCO 3 − at the basolateral membrane. The following mechanism is suggested to account for the rise in luminal Cl− concentration above equilibrium values: intracellular CO2 hydration gives rise to cell HCO 3 − concentrations above equilibrium. The passive exit of HCO 3 − at the basolateral membrane energizes an uphill entry of Cl− into the cell. The resulting increase of α i Cl , above equilibrium, generates downhill Cl− diffusion from cell to lumen. As a result, luminal Cl− concentration also increases.
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  • 5
    ISSN: 1432-1424
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The basal-lateral surface of the epithelium of the urinary bladder of the toad (Bufo marinus) was depolarized by exposure of the serosal surface to 85mm KCL and 50mm sucrose. The extent of depolarization appeared to be virtually complete, as evaluated by the invariance in the transepithelial electrical potential difference and conductance on addition of nystatin (a monovalent cation ionophore) to the serosal medium. The Na-specific current (I Na) was defined as the current sensitive to the removal of Na from the mucosal medium or inhibitable by addition of amiloride to this medium. In the presence of the high K-sucrose serosal medium, rapid, serial, stepwise clamping of the transepithelial voltage (V) yielded a curvilinear dependence ofI Na onV; which is taken to represent theI–V curve of the apical Na channels. The constant field equation (Goldman, D.E. 1943;J. Gen. Physiol. 27:37) fits theI–V data points closely, allowing estimates to be made of the permeability to Na of the apical membrane (P Na) and of the intracellular Na activity (Na c ). Exposure of the apical surface to amiloride (5×10−7 m) decreasedP Na in proportion to the decrease inI Na (i.e., ∼70%) but decreased Na c only 25%. In contrast, an equivalent lent reduction inI Na elicited by exposure of the basallateral surface to ouabain was accompanied by only a 20% decrease inP Na and a sixfold increase in Na c . The effects of amiloride onP Na and ouabain on Na c are consistent with the primary pharmacological actions of these drugs. In addition,P Na appears to be under metabolic control, in that 2-deoxyglucose, a specific inhibitor of glycolysis, decreasedI Na andP Na proportionately, and lowered Na c marginally, effects indistinguishable from those obtained with amiloride.
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  • 6
    ISSN: 1432-1424
    Keywords: aldosterone ; metabolic regulation ; sodium permeability ; toad bladder
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary In the present study, further evidence was adduced for energy-dependent regulation of passive apical transport of Na in toad bladder epithelium. In potassium-depolarized preparations studied by current-voltage analysis, additions of pyruvate or glucose to the media of substrate-depleted bladders evoked propertionate increases in the transepithelial Na current and in apical Na permeability. These reponses were large in aldosterone pretreated hemibladders and almost absent in the aldosterone-depleted preparations or when hormonal action was blocked by spironolactone or cycloheximide. The substrateinduced increases in apical Na permeability were fully reversed by appropriate metabolic inhibitors, i.e. 2-deoxyglucose and oxythiamine. Moreover, the inhibitory effect of 2-deoxyglucose was bypassed by the addition of pyruvate to the serosal medium. Thus apical Na permeability is clearly sensitive to the supply of cellular energy. The possibility that changes in intrcellular free Na activity may mediate metabolic regulation of apical Na permeability was evaluated by prolonged exposure to Na-free mucosal and serosal media, with and without inhibition of the Na/K-pump by ouabain. The stimulatory and inhibitory effects of pyruvate, 2-deoxyglucose and oxythiamine on Na currents and Na conductances were preserved under these circumstances. Furthermore, reduction of serosal Ca to a minimal level of 3 μm, was without effect on the response to metabolic inhibition. These experiments demonstrate the existence of Na-independent metabolic regulation of apical Na transport and imply that neither basal-lateral nor mitochondrial Na/Ca exchange is required for this regulatory process under the imposed conditions. The possibility that a Na-independent, Ca transport mechanism in mitochondria or endoplasmic reticulum may be involved in metabolic regulation of apical Na transport, however, remains to be evaluated.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    The journal of membrane biology 64 (1982), S. 91-102 
    ISSN: 1432-1424
    Keywords: transepithelial Na transport ; apical Na permeability ; Na-channel density ; aldosterone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Near-instantaneous current-voltage relationships and shot-noise analysis of amiloride-induced current fluctuations were used to estimate apical membrane permeability to Na (P Na), intraepithelial Na activity (Na c ), single-channel Na currents (i) and the number of open (conducting) apical Na channels (N0), in the urinary bladder of the toad (Bufo marinus). To facilitate voltageclamping of the apical membrane, the serosal plasma membranes were depolarized by substitution of a high KCl (85mm) sucrose (50mm) medium for the conventional Na-Ringer's solution on the serosal side. Aldosterone (5×10−7 m, serosal side only) elicited proportionate increases in the Na-specific current (I Na and inP Na, with no significant change in the dependence ofP Na on mucosal Na (Na o ).P Na and the control ofP Na by aldosterone were substrate-dependent: In substrate-depleted bladders, pretreatment with aldosterone markedly augmented the response to pyruvate (7.5×10−3 m) which evoked coordinate and equivalent increases inI Na andP Na. The aldosterone-dependent increase inP Na was a result of an equivalent increase in the area density of conducting apical Na channels. The computed single-channel current did not change. We propose that, following aldosterone-induced protein synthesis, there is a reversible metabolically-dependent recruitment of preexisting Na channels from a reservoir of electrically undetectable channels. The results do not exclude the possibility of a complementary induction of Na-channel synthesis.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-1424
    Keywords: Na/K-ATPase ; antibodies ; biosynthesis ; crossreactivity ; cell-free synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Antibodies have been produced, in three rabbits, to Na/K-ATPase purified from guinea pig renal outer medulla. Each rabbit produced antibodies to both the α (catalytic) and the β (glycoprotein) subunits of Na/K-ATPase. The titers of the anti-α and anti-β antibodies varied with time and between rabbits. None of the antisera inhibited Na/K-ATPase activity under various preincubation conditions. A method is presented for separating small amounts of anti-α subunit from anti-β subunit antibodies. There was not cross-reactivity of antibodies to one subunit with the other subunit. The α subunit of the Na/K-ATPase was cleaved into a 41,000-dalton peptide (that contains the ATP phosphorylating site) and a 58,000-dalton hydrophobic peptide as described by Castro and Farley (Castro, J., Farley, R.A., 1979,J. Biol. Chem. 254:2221–2228). Anti-α antibodies from all of the rabbits reacted with both proteolytic fragments. The anti-guinea pig Na/K-ATPase antisera (pooled) cross-reacted with the α subunit of Na/K-ATPase from human, cow, dog, rabbit, rat mouse, turtle, and toad; and with the β subunit from human, rat, and mouse. The loci of cross-reactivity were investigated using partially purified canine kidney Na/K-ATPase cleaved with trypsin as described above. The antisera from rabbits 1 and 2 cross-reacted with the 41,000-dalton peptide from the dog but very little with the 58,000-dalton peptide. No cross-reactivity was observed with antiserum from rabbit 3 to either fragment. Guinea pig kidney RNA was translated in a rabbit reticulocyte lysate system followed by immunoprecipitation with the antisera. The molecular weight of the cell-free synthesized α chain was 96,000 daltons. Its identity was established with purified anti-α antibodies and by immunocompetition with purified Na/K-ATPase and Ca-ATPase. Translation of the β subunit was not detected in this system.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    International journal of immunogenetics 10 (1983), S. 0 
    ISSN: 1744-313X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Two murine monoclonal antibodies (E11-1 and MR4-130) agglutinated all samples of human red cells except those of the Ge (-1, -2, -3) phenotype. It was possible to demonstrate that these antibodies recognize two different epitopes of the Gerbich antigen.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Neuroscience 7 (1984), S. 339-377 
    ISSN: 0147-006X
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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