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  • excitation-contraction coupling  (3)
  • permeability  (3)
  • Korea
  • Springer  (6)
  • American Geophysical Union (AGU)
  • 1990-1994  (6)
Collection
Keywords
Publisher
  • Springer  (6)
  • American Geophysical Union (AGU)
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Year
  • 1
    Electronic Resource
    Electronic Resource
    Regulation of Ca2+ release from sarcoplasmic reticulum in skeletal muscles (1992)
    Springer
    Molecular and cellular biochemistry 114 (1992), S. 105-108 
    Details
    ISSN: 1573-4919
    Keywords: calmodulin ; calmodulin kinase ; excitation-contraction coupling ; muscle contraction ; skeletal muscle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Ca2+ release from skeletal sarcoplasmic reticulum (SR) could be regulated by at least three mechanisms: 1) Ca2+, 2) calmodulin, and 3) Ca2+/calmodulin-dependent phosphorylation. Bell-shaped Ca2+-dependence, of Ca2+ release from both actively- and passively-loaded SR vesicles suggest that opening and closing of the Ca2+ release channel could be regulated by [Ca2+ o] . The time- and concentration-dependent inhibition of Ca 2+ release from skeletal SR by calmodulin was also studied using passively-Ca2+ loaded SR vesicles. Up to 50% of Ca 2+ release was inhibited by calmodulin (0.01–0.5 µM); this inhibition required 5–15 min preincubation time. The hypothesis that Ca2+/calmodulin-dependent phosphorylation of a 60 kDa protein regulates Ca2+ release from skeletal SR was tested by stopped-flow fluorometry using passively-Ca2+-loaded SR vesicles. Approximately 80% of the initial rates of Ca2+-induced Ca2+ release was inhibited by the phosphorylation within 2 min of incubation of the SR with Mg·ATP and calmodulin. We identified two types of 60 kDa phosphoproteins in the rabbit skeletal SR, which was distinguished by solubility of the protein in CHAPS. The CHAPS-soluble 60 kDa phosphoprotein was purified by column chromatography on DEAE-Sephacel, heparin-agarose, and hydroxylapatite. Analyses of the purified protein indicate that the CHAPS-soluble 60 kDa protein is an isoform of phosphoglucomutase (PGM). cDNAs encoding isoforms of PGM were cloned and sequenced using synthetic oligonucleotides. Two types of PGM isoforms (Type I and Type 11) were identified. The translated amino acid sequences show that Type II isoform is SR-form. Our results are significant in terms of understanding evidence of an association of glycolytic and glycogenolytic enzymes with SR and a role in the regulation of SR functions. (Mol Cell Biochem 114: 105-108, 1992)
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00240304
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  • 2
    Electronic Resource
    Electronic Resource
    A new model for impregnation mechanisms in different GF/PP commingled yarns (1994)
    Springer
    Applied composite materials 1 (1994), S. 351-371 
    Details
    ISSN: 1573-4897
    Keywords: commingled yarn ; impregnation ; consolidation ; thermoplastics ; processing ; permeability ; mechanical testing ; mathematical modelling ; compression moulding ; glass fibre bed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Impregnation mechanisms of different kinds of GF/PP commingled yarns have been studied. As the reinforcing fibres were always the same, a global description has been worked out. Two different mathematical approaches for fibre bed permeability (Kozeny-Carman and Gutowski) were compared. The constants of the applied mathematical models have to stay the same if the fibre reeinforcement and the fibre arrangement is the same. Neither the kind of matrix, nor the fibre volume content may change these constants. Differences in the degree of impregnation after the same process conditions can be only due to different sizes of fibre agglomerations, thus the initial distribution of reinforcing fibres and matrix. For an exact determination of impregnation times and conditions the exact distribution of fibres in the intermediate material and after processing has to be known. This distribution is determined by SEM microscopy and data given from the material supplier. The importance of different process parameters, such as temperature, pressure, processing time is weighted by determining the density and mechanical properties of the specimens.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00568041
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  • 3
    Electronic Resource
    Electronic Resource
    Identification of a new subpopulation of triad junctions isolated from skeletal muscle; Morphological correlations with intact muscle (1990)
    Springer
    The journal of membrane biology 113 (1990), S. 221-235 
    Details
    ISSN: 1432-1424
    Keywords: excitation-contraction coupling ; triad junctions ; dihydropyridine receptor ; ryanodine receptor ; strong triads
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary It has been previously recognized that a number of protocols may cause breakage of the triad junction and separation of the constituent organelles of skeletal muscle. We now describe a fraction of triad junctions which is refractory to the known protocols for disruption. Triads were passed through a French press and the dissociated organelles were separated on a sucrose density gradient, which was assayed for PN200-110, ouabain and ryanodine binding. Ryanodine binding showed a single peak at the density of heavy terminal cisternae. On the other hand, the PN200-110 and ouabain, which are external membrane ligands, bound in two peaks: one at the free transverse tubule region and the other at the light terminal cisternae. Similarly, a two peak pattern of PN200-110 and ouabain binding was observed when triad junctions were broken by the Ca2+-dependent protease, calpain, which selectively hydrolyzes the junctional foot protein. The light terminal cisternae vesicles were subjected to three different procedures of junctional breakage: French press, hypertonic salt treatment, and protease digestion using calpain or trypsin. The treated membranes were then centrifuged on density gradients. Only extensive trypsin digestion caused a partial shift of ouabain activity into the free transverse tubule region. These observations suggest that the triads are a composite mixture of breakage susceptible, “weak,” and breakage resistant, “strong,” triads. Scatchard analysis of PN200-110 suggests that the transverse tubules of strong triads contain a relatively high number of dihydropyridine receptors compared to those of weak triads. Thin section electron microscopic images of the strong triads comparable to those of intact muscle are presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01870074
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  • 4
    Electronic Resource
    Electronic Resource
    Comparison of calcium release from sarcoplasmic reticulum of slow and fast twitch muscles (1991)
    Springer
    The journal of membrane biology 122 (1991), S. 155-163 
    Details
    ISSN: 1432-1424
    Keywords: Ca2+ release channel ; excitation-contraction coupling ; slow twitch skeletal muscle ; tast twitch skeletal muscle ; planar lipid bilayers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The mechanism of Ca2+ release from the sarcoplasmic reticulum (SR) of slow and fast twitch muscle was compared by examining biochemical characteristics, ryanodine binding. Ca2+ efflux, and single Ca2+ channel properties of SR vesicles. Although many features of the Ca2+ release channel were comparable, two functional assays revealed remarkable differences. The comparable properties include: a high molecular weight protein from both types of muscle was immunologically equivalent, and Scatchard analysis of [3H]ryanodine binding to SR showed that theK d was similar for slow and fast SR. In the flux assay the sensitivity to the agonists caffeine, doxorubicin, and Ca2+ and the antagonists Mg2+, ruthenium red, and tetracaine differed only slightly. When SR vesicles were incorporated into lipid bilayers, the single-channel conductances of the Ca2+ release channels were indistinguishable. The distinguishing properties are: When Ca2+ release from passively45Ca2+-loaded SR were monitored by rapid filtration, the initial rates of Ca2+ release induced by Ca2+ and caffeine were three times lower in slow SR than in fast SR. Similarly, when Ca2+ release channels were incorporated into lipid bilayers, the open probability of the slow SR channel was markedly less, mainly due to a longer mean closed time. Our results indicate that slow and fast muscle have ryanodine receptors that are biochemically analogous, yet functional differences in the Ca2+ release channel may contribute to the different time to peak contraction observed in intact slow and fast muscles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01872638
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  • 5
    Electronic Resource
    Electronic Resource
    Studies on the mechanisms of active ion fluxes across alveolar epithelial cell monolayers (1992)
    Springer
    Methods in cell science 14 (1992), S. 187-193 
    Details
    ISSN: 1573-0603
    Keywords: transport ; epithelium ; edema ; beta-agonist ; barrier ; permeability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary To investigate the cell physiologic and biological properties of the alveolar epithelium, we studied rat alveolar epithelial cell monolayers grown on permeable supports in primary culture. Type II alveolar epithelial cells were disaggregated using elastase, and partially purified on a discontinuous metrizamide gradient. These isolated cells were plated onto tissue culture-treated Nuclepore membrane filters at 1.5×106 cells/cm2 and maintained in a humidified incubator (5% CO2 in air, 37° C). After 2 days in culture, the bathing media on both sides of the cell monolayers were changed to fresh culture medium, thus removing nonadherent cells (mostly leukocytes). These monolayers exhibit a high transmonolayer resistance (〉2000 Ω-cm2) and actively transport ions. Radionuclide flux studies indicate that Na+ is the predominant ionic species absorbed actively under baseline conditions, accounting for about 80% of the total active ion transport. Cl− seems to be passively transported across the epithelium. However, when the epithelium is exposed to a beta-agonist (terbutaline), active absorption of Na+ is increased and active absorption of Cl− occurs. Although it is clear that both active Na+ and Cl− transport are dependent on Na+/K+-ATPase activity, and that Na+ enters cells predominantly through channels, the specific mechanisms by which Cl− enters and exits the alveolar epithelial cells remain unclear. The stimulated reabsorption of Na+ and Cl− may be important in helping to remove excess fluid from alveolar air spaces in the lung.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01409010
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  • 6
    Electronic Resource
    Electronic Resource
    Transport of Thyrotropin Releasing Hormone in Rabbit Buccal Mucosa in Vitro (1992)
    Springer
    Pharmaceutical research 9 (1992), S. 1113-1122 
    Details
    ISSN: 1573-904X
    Keywords: thyrotropin releasing hormone ; buccal mucosa ; metabolism ; permeability ; in vitro tissue integrity ; transport pathways ; rate-limiting barrier
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The transport of thyrotropin releasing hormone (TRH) in rabbit buccal mucosa in vitro has been investigated with respect to (a) rate and type of metabolism of TRH on mucosal and serosal sides of buccal mucosa, (b) mechanism of TRH transport including charge effect on its permeability, and (c) pathway and rate-limiting regions of TRH movement. In addition, the integrity of excised buccal mucosa has been evaluated for purposes of in vitro solute diffusion experiments using tissue ATP level data, transmission electron microscopy, and TRH transport kinetic data. The results indicate that excised rabbit buccal mucosa can be used for TRH diffusion studies for approximately 6 hr. In addition, TRH apparently traverses buccal mucosa by simple diffusion with a steady-state permeability of about 10−7 cm/sec, and this permeability is independent of pH. Moreover, the primary pathway appears to be via the intercellular space in the rate-limiting barrier, i.e., the upper 50 µm of the epithelium. Finally, TRH is degraded predominantly by deamidase activity, which is followed by, to a lesser degree, carboxypeptidase metabolism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015883217858
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