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  • Polymer and Materials Science  (2)
  • sodium excretion  (1)
  • squid axon  (1)
  • 1985-1989  (4)
  • 1890-1899
  • 1988  (4)
Collection
Keywords
Publisher
Years
  • 1985-1989  (4)
  • 1890-1899
Year
  • 1
    Electronic Resource
    Electronic Resource
    Effects of arachidonic acid and the other long-chain fatty acids on the membrane currents in the squid giant axon (1988)
    Springer
    The journal of membrane biology 106 (1988), S. 141-147 
    Details
    ISSN: 1432-1424
    Keywords: arachidonic acid ; long-chain fatty acids ; membrane currents ; Na channel ; squid axon ; membrane excitation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The effects of arachidonic acid and some other long-chain fatty acids on the ionic currents of the voltage-clamped squid giant axon were investigated using intracellular application of the test substances. The effects of these acids, which are usually insoluble in solution, were examined by using α-cyclodextrin as a solvent. α-cyclodextrin itself had no effect on the excitable membrane. Arachidonic acid mainly suppresses the Na current but has little effect on the K current. These effects are completely reversed after washing with control solution. The concentration required to suppress the peak inward current by 50% (ED50) was 0.18mm, which was 10 times larger than that of medium-chain fatty acids like 2-decenoic acid. The Hill number was 1.5 for arachidonic acid, which is almost the same value as for medium-chain fatty acids. This means that the mechanisms of the inhibition are similar in both long- and medium-chain fatty acids. When the long-chain fatty acids were compared, the efficacy of suppression of Na current was about the same value for arachidonic acid, docosatetraenoic acid and docosahexaenoic acid. The suppression effects of linoleic acid and linolenic acid on Na currents were one-third of that of arachidonic acid. Oleic acid had a small suppression effect and stearic acid had almost no effect on the Na current. The currents were fitted to equations similar to those proposed by Hodgkin and Huxley (Hodgkin, A.L., Huxley, A.F. (1952)J. Physiol (London) 117:500–544) and the change in the parameters of these equations in the presence of fatty acids were calculated. The curve of the steady-state activation parameter (m ∞) for the Na current against membrane potential and the time constant of activation (τ m ) were shifted 10 mV in a depolarizing direction by the application of fatty acids. The time constant for inactivation (τ h ) has almost unaffected by application of these fatty acids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01871396
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  • 2
    Electronic Resource
    Electronic Resource
    A Quantitative Method of Evaluating the Diuretic Response to Furosemide in Rats (1988)
    Springer
    Pharmaceutical research 5 (1988), S. 694-698 
    Details
    ISSN: 1573-904X
    Keywords: furosemide ; diuresis ; sodium excretion ; potassium excretion ; chloride excretion ; urinary excretion rate ; urinary electrolytes in rats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Furosemide effects are usually evaluated by measuring the urinary excretion rate of Na+ (UVNa) in humans. In the present study, however, UVNa showed a nonlinear relationship with urine flow rate after intravenous injection of furosemide in rats. In contrast, when the urinary excretion rate of (Na+ + K+) (UVNa+K) was plotted against the urine flow rate, a linear regression line was observed, with small interindividual variations in normal rats and in rats with uranyl nitrate-induced acute renal failure (ARF). Piretanide, a loop diuretic, also showed a similar relationship, while other types of diuretics revealed different slope values for the relationship. Although the urinary excretion rate of Cl− (UVC1) vs UVNa+K is expected to show a linear relationship in normal rats, the correlation coefficient of the linear regression line was smaller than that of the urine flow rate vs UVNa+K. Further, the slope of UVC1 vs UVNa+K was slightly different in ARF rats. Therefore, UVNa+K provides a better quantitative measure of diuretic response to loop diuretics than UVNa or UVC1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015999626133
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  • 3
    Electronic Resource
    Electronic Resource
    Structural and energetic parameters of Ca2+ binding to peptides and proteins (1988)
    New York : Wiley-Blackwell
    Biopolymers 27 (1988), S. 1865-1886 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The characteristics of Ca2+-binding sites and of the structural reorganization induced by Ca2+-binding in storage proteins and ion carriers are being studied as models for molecular mechanisms in Ca2+ channels and in Ca2+-dependent modulatory proteins. A first step in the study was the development of energy parameters for Ca2+ compatible with those in the CHARMM package of computer simulation software. Such parameters were obtained from an analytical fit to the potential surface for [(Ca)(OCH2)4]2+ calculated with an ab initio molecular orbital method. The resulting parametrization was tested for the hexapeptide cyclo-(Pro-Gly)3, and a 75 residue long calcium binding protein from bovine intestine (ICaBP). The geometrical parameters calculated for the hexapeptide and its 2:1 complex with Ca2+ were in good agreement with experimental data from crystallography and nmr. Similarly, the structure of ICaBP optimized with CHARMM using the new Ca2+ parameters showed good agreement with the x-ray structure both in the local structures of the calcium-binding sites and in the overall shape of the protein.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360271202
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  • 4
    Electronic Resource
    Electronic Resource
    Ionic products in ground polymer. IV. Anions in poly(vinylidene fluoride) (1988)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 26 (1988), S. 1307-1312 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: When poly(vinylidene fluoride) (PVDF) was ground with tetracyanoethylene (TCNE) powder in a vibration glass ball mill in vacuum in the dark at 77 K, the TCNE anion radical (TCNE-) was detected in the mixture by ESR spectroscopy. The TCNE.- is formed by the abstraction of electrons by TCNE from the anion that is produced by a heterogeneous bond scission of carbon-carbon bonds in the polymer main chain. The assignment of TCNE.- was carried out by the ESR spectral simulation on the basis of an anisotropic effective hyperfine tensor that includes a forbidden transition term. At least 85% of the bond scission of the PVDF main chain is induced by a heterogeneous process to produce ionic products. The yield of these mechanions seems to increase with the polarity of carbon-carbon bond owing to a substituent group bonded to the carbon in the polymer main chain.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1988.090260614
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