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  • Analytical Chemistry and Spectroscopy  (3)
  • OCT1  (2)
  • 1995-1999  (5)
  • 1
    Electronic Resource
    Electronic Resource
    Transport of small organic cations in the rat liver (1996)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 354 (1996), S. 320-326 
    Details
    ISSN: 1432-1912
    Keywords: Rat liver ; Transport of organic cations ; OCT1 ; Type I hepatic transport of cationic drugs ; 1-Methyl-4-phenylpyridinium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The kidneys and the liver are the principal organs for the inactivation of circulating organic cations. Recently, an organic cation transporter (OCT1) has been cloned from rat kidney. In order to answer the question whether OCT1 is involved also in hepatic uptake of organic cations, the pharmacological characteristics of organic cation transport in hepatocytes were compared to the characteristics of transiently expressed OCT1. Primary cultures of rat hepatocytes avidly accumulated the small organic cation 3H-1-methyl-4-phenylpyridinium (3H-MPP+). At equilibrium, the hepatocytes accumulated 3H-MPP+ 56-fold. Initial rates of specific 3H-MPP+ transport in hepatocytes were saturable. The half-saturating concentration was 13 μmol/l. 3H-MPP+ transport was sensitive to quinine (Ki = 0.79 μmol/l) and cyanine863 (Ki = 0.097 µmol/l). Quinine and cyanine863 are known inhibitors of type I hepatic transport of cationic drugs and of renal excretion of organic cations, respectively. To compare the functional characteristics of 3H-MPP+ transport in hepatocytes with those of OCT1, OCT1 has been heterologously expressed and characterized in a mammalian cell line (293 cells). Initial rates of 3H-MPP+ transport were saturable, the Km being 13 μmol/l. The rank order of inhibitory potencies of various inhibitors was almost identical in hepatocytes and 293 cells transiently transfected with OCT1. There was a positive correlation between the Ki's for the inhibition of 3H-MPP+ transport in isolated hepatocytes and transfected 293 cells (r = 0.85; P〈0.01; n = 8). The results indicate that OCT1 is functionally expressed not only in the kidney but also in hepatocytes where it is responsible for the transport of small organic cations which, in the past, have been classified as type I substrates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00171063
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Transport of small organic cations in the rat liver The role of the organic cation transporter OCT1 (1996)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 354 (1996), S. 320-326 
    Details
    ISSN: 1432-1912
    Keywords: Key words Rat liver ; Transport of organic cations ; OCT1 ; Type I hepatic transport of cationic drugs ; 1-Methyl-4-phenylpyridinium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The kidneys and the liver are the principal organs for the inactivation of circulating organic cations. Recently, an organic cation transporter (OCT1) has been cloned from rat kidney. In order to answer the question whether OCT1 is involved also in hepatic uptake of organic cations, the pharmacological characteristics of organic cation transport in hepatocytes were compared to the characteristics of transiently expressed OCT1. Primary cultures of rat hepatocytes avidly accumulated the small organic cation 3H-1-methyl-4-phenylpyridinium (3H-MPP+). At equilibrium, the hepatocytes accumulated 3H-MPP+ 56-fold. Initial rates of specific 3H-MPP+ transport in hepatocytes were saturable. The half-saturating concentration was 13 μmol/l. 3H-MPP+ transport was sensitive to quinine (Ki = 0.79 μmol/l) and cyanine863 (Ki = 0.097 μmol/l). Quinine and cyanine863 are known inhibitors of type I hepatic transport of cationic drugs and of renal excretion of organic cations, respectively. To compare the functional characteristics of 3H-MPP+ transport in hepatocytes with those of OCT1, OCT1 has been heterologously expressed and characterized in a mammalian cell line (293 cells). Initial rates of 3H-MPP+ transport were saturable, the Km being 13 μmol/l. The rank order of inhibitory potencies of various inhibitors was almost identical in hepatocytes and 293 cells transiently transfected with OCT1. There was a positive correlation between the Ki’s for the inhibition of 3H-MPP+ transport in isolated hepatocytes and transfected 293 cells (r = 0.85; P〈0.01; n = 8). The results indicate that OCT1 is functionally expressed not only in the kidney but also in hepatocytes where it is responsible for the transport of small organic cations which, in the past, have been classified as type I substrates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00171063
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Gas chromatographic separation of chiral organochlorines on modified cyclodextrin phases and results of marine biota samples (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 85-93 
    Details
    ISSN: 0935-6304
    Keywords: Capillary gas chromatography ; Modified cyclodextrin phases ; Chiral organochlorines ; Biological samples ; Enantiomeric ratios ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Four chiral stationary phases containing modified cyclodextrines diluted in or chemically bonded to a non-chiral phase were used to resolve chiral organochlorine compounds such as α-hexachlorocyclohexane (α-HCH), perdeuterated α-HCH (α-PDHCH), β-and γ-pentachlorocyclohexene (PCCH), oxychlordane, cis-and trans-chlor- dane, cis- and trans-heptachlorepoxide, PCB 95, PCB 132, PCB 149, and Chiral tozaphenes.The elution order was determined by analyzing standards with known enantiomeric excesses.Furthermore, an internal standard was used to even out slight variations in the ratio of peak hights of enantiomers which were determined from injection to injection.None of the chiral stationary phases resolved all chiral organochlorine compounds. However, the β-TBDM(35% heptakis (6-O-t-butyldimethylsilyl-2,3-di-O-methyl)-β-cyclodextrin in OV 1701) column allowed the separation of all compounds under investigation except for PCB 95 and chiral toxaphenes.Emphasis was placed on the separation of as many as possible enantiomers on a chiral phase by application of one temperature program and with respect to unambiguous quantitation of biological samples such as bludder and liver of marine and terrestrial mammals.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200208
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  • 4
    Electronic Resource
    Electronic Resource
    Synthesis, isolation, and chromatography of perdeuterated α-1,2,3,4,5,6-hexachlorocyclohexane (1995)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 18 (1995), S. 643-646 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography/Mass spectrometry ; Chiral GC ; Deuterium-labeled compounds ; Hexachlorocyclohexane ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Perdeuterated α-1,2,3,4,5,6-hexachlorocyclohexane (α-PDHCH) was synthesized and isolated in pure form. α-PDHCH was baseline separated from unlabeled α-HCH by high resolution gas chromatography on different stationary phases. α-PDHCH was also resolved into its enantiomeric forms by application of a chiral GC phase. Furthermore, chiral chromatography of a mixture of labeled α-PDHDH and unlabeled α-HCH resulted in four peaks. Standard solutions of α-PDHCH are recommended both as recovery standard for sample clean-up and as internal standard for the quantitation of chlorinated hydrocarbons with GC/MS or GC/ECD in environmental samples.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240181006
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  • 5
    Electronic Resource
    Electronic Resource
    A method for counting disulfide bridges in small proteins by reduction with mercaptoethanol and electrospray mass spectrometry (1995)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 30 (1995), S. 1562-1566 
    Details
    ISSN: 1076-5174
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A simple and rapid method for counting the number of internal disulfide bridges in a protein by incubation with 2-mercaptoethanol and electrospray mass spectrometry analysis of the products was developed. 2-Mercaptoethanol yields intermediate mixed disulfides during reduction of a protein. This results in a molecular weight increase of the protein by 78 Da per disulfide bond, which can easily be determined by electrospray mass spectrometry (ESMS). The number of mercaptoethanol adducts observed by ESMS reveals the number of disulfide bridges in the peptide or protein. Since the protein-mercaptoethanol-disulfide bonds are themselves further reduced by excess mercaptoethanol, the course of the reaction has to be followed in order to detect the maximum number of intermediates. Owing to the volatility of mercaptoethanol, samples can be taken out of the reaction solution for MS analysis without prior purification. Successful experiments were carried out using proteins with one, two, four or six S—S-bonds, covering a mass range from about 1 to over 23 kDa.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jms.1190301107
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