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  • 1
    ISSN: 0022-4731
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Archives of gynecology and obstetrics 217 (1974), S. 303-308 
    ISSN: 1432-0711
    Keywords: umbilical cord artery ; oxygen induced constriction ; vasodilatatory pharmaca
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Es wurde die Wirkung verschiedener gefäßerweiternder Pharmaka auf die sauerstoffbedingte Vasokonstriktion der isolierten und künstlich perfundierten menschlichen Nabelschnurarterie untersucht. Dabei zeigte sich: 1. die sauerstoffbedingte Konstriktion kann durch Glyceryl-Trinitrat (2 μg/ ml) verhindert und aufgehoben werden 2. Methysergid kann die O2-Wirkung weder unterbinden noch beseitigen, unterdrückt aber vollständig eine durch Serotonin (5-OH-Tryptamin; 10μg/ml) hervorgerufenen Vasokonstriktion 3. Phentolamin, Tolazolin und Propranolol haben keinen Einfluß auf die sauerstoffbedingte Konstriktion. Sie können auch die geringe, durch Norepinephrin verursachte Gefäßverengung nicht verhindern. 4. Isproterenol und Buphenin beeinflussen den Gefäßwiderstand der isolierten Nabelschnurarterie nicht.
    Notes: Summary The effect of various vasodilating pharmaca on the oxygen induced vasoconstriction of the isolated, artificially perfused human umbilical cord artery is investigated. It is demonstrated that: 1. the oxygen induced constriction can be prevented and abolished by glyceryl-trinitrate (2μg/ml) 2. Methysergid neither abolishes nor prevents the oxygen induced vasoconstriction though the serotonine (5-OH-tryptamine) induced constriction (10μg/ml) is completely suppressed 3. phentolamine, tolazoline and propranolol do not affect the O2-induced contraction. These sympathicolytic agents cannot hinder the slight constriction caused by norepinephrine 4. isoproterenol and buphenine do not influence the vascular resistance of the umbilical cord artery.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Archives of gynecology and obstetrics 211 (1971), S. 146-147 
    ISSN: 1432-0711
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Archives of gynecology and obstetrics 219 (1975), S. 342-342 
    ISSN: 1432-0711
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Archives of gynecology and obstetrics 222 (1977), S. 187-196 
    ISSN: 1432-0711
    Keywords: Human placenta ; Isolated cotylidon ; Placental transfer ; D-Glucose ; L-Glucose ; D-Mannose ; D-Mannitol ; Phloretin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Isolierte Cotyledonen reifer geborener Plazenten werden fetal und matern künstlich perfundiert. Dabei wird der relative transplazentare Transport von radioaktiv markierter D-Glukose, L-Glukose, D-Mannose und D-Mannitol gemessen und die Hemmbarkeit des Transportes mit Phloretin geprüft: 1. Die Transferraten für D-Glukose und D-Mannose liegen 1,5–4mal höher als für L-Glukose. 2. Phloretin (10−3 Mol/l) hemmt den Transport der D-Hexosen, während der Transport von L-Glukose praktisch unbeeinflußt bleibt. 3. Bei steigenden Angebotskonzentrationen von D-Glukose wird der Transport von D-Mannose kompetetiv gehemmt. 4. Die Transferraten für L-Glukose und D-Mannitol sind gleich groß. Die Ergebnisse zeigen, daß D-Hexosen durch die Humanplazenta mit Hilfe eines spezifischen Carriers sowie durch einfache Diffusion gelangen.
    Notes: Summary Isolated cotylidons of human term placentas are perfused artificially on the fetal and maternal side. The relative transfer rates of radioactive labelled D-glucose, L-glucose, D-mannose and D-mannitol across the placenta are measured and the inhibition of these transports by phloretin is studied: 1. Transfer rates of D-glucose and D-mannose exceed that of L-glucose about 1.5–4 times. 2. Phloretin (10−3 mol/l) decreases the transports of D-hexoses, whereas the transport of L-glucose remains unaffected. 3. If the concentration of D-glucose is increased, the transport of D-mannose is inhibited competitively. 4. L-glucose and D-mannitol equal in transfer rates. These results show, that D-hexoses cross the human placenta by a specific carrier and by simple diffusion.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Archives of gynecology and obstetrics 215 (1973), S. 299-303 
    ISSN: 1432-0711
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung 7 reife und 3 unreife (12.–24. Schwangerschaftswoche) menschliche Placenten wurden mit der Mikroelektrodentechnik auf das Vorhandensein von elektrischen Zellpotentialen hin untersucht. Dabei ergab sich: 1. Bei der reifen menschlichen Placenta treten überwiegend (91%) Zellpotentiale zwischen 0 und 20 mV auf. 2. Bei unreifen menschlichen Placenten sind Zellpotentiale zwischen 20–65 mV mit einer Häufigkeit von 78% vorhanden. 3. Diese Potentiale waren unter unseren Versuchsbedingungen nach 3 Std praktisch nicht mehr nachweisbar. Diese Veränderung der Zellpotentiale im Verlaufe der Schwangerschaft stehen im Einklang mit anderen Einschränkungen der Placentafunktion wie dem Natriumtransport oder dem Sauerstoffverbrauch.
    Notes: Summary 7 mature and 3 immature (12.–24. week of gestation) human placentas were studied by means of glass microelectrodes for the presence of cell potentials. It could be shown: 1. In the mature human placenta mostly (91%) cellpotentials between 0 and 20 mV are found. 2. In the immature human placenta cell potentials between 20 and 65 mV exist with a frequency of 78%. 3. In our experiments the potentials had disappeared after 3 hours. The observed decrease of cell potentials in course of gestation agree well with other restrictions of placental function as the transport of Na+ or the oxygen consumption.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Archives of gynecology and obstetrics 219 (1975), S. 353-355 
    ISSN: 1432-0711
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Archives of gynecology and obstetrics 215 (1973), S. 305-313 
    ISSN: 1432-0711
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Es wurden Zellpotentiale in der Meerschweinchenplacenta gemessen und die intracelluläre Kalium- bzw. Natriumkonzentration in diesem Organ annähernd bestimmt. Dabei ergab sich: 1. Isolierte Placenten weisen innerhalb von 30 min nach Unterbrechung der Durchblutung Zellpotentiale am häufigsten zwischen 20 und 45 mV auf. Diese Potentiale verschwinden im Verlauf von ca. 4 Std. 2. Durchblutete in situ befindliche Placenten haben Zellpotentiale in gleicher Höhe wie die isolierten. 3. Die Zellpotentiale in der isolierten, matern und fetal künstlich perfundierten Placenta sind im Mittel ca. 10 mV höher als die Potentiale der isolierten und in situ Placenta. 4. Durch Erhöhung der Kaliumkonzentration im Perfusionsmedium von 5 mVal auf 105 mVal nimmt die Höhe der Zellpotentiale in der perfundierten Placenta reversibel ab. 5. Die annäherungsweise gemessene intracelluläre Kalium- bzw. Natriumkonzentration in der Placenta beträgt 46 mVal bzw. 83 mVal. Diese Befunde sprechen dafür, daß die Zellpotentiale in der Meerschweinchenplacenta, die mit großer Wahrscheinlichkeit im Trophoblasten gemessen wurden, durch die Differenz zwischen der intra- und extracellulären Kaliumkonzentration hervorgerufen werden. Der Transport von Ionen, wie z.B. Natrium durch den Trophoblasten, muß elektrochemische Konzentrationsunterschiede überwinden.
    Notes: Summary In the guinea pig placenta cell potentials and approximatively the intracellular concentrations of Na+ resp. K+ were measured. It is shown: 1. Isolated placentas mostly have cell potentials between 20 and 45 mV within 30 min after disconnection from circulation. The potentials disappear within 4 hours. 2. In-situ-placentas have cell potentials in the same order of magnitude as the isolated placentas. 3. Cell potentials in the wholly isolated, artificially perfused placenta are somewhat higher (ca. 10 mV) than the potentials of the isolated and in-situ placentas. 4. Raising the concentration of K+ in the perfusion medium from 5 mVal to 105 mVal leds to a decrease of the magnitude of the cell potentials in the perfused placenta which is reversible. 5. The approximatively measured intracellular concentrations are about 46 mVal K+ and 83 mVal Na+. These results support the assumption, that cell potentials in the guinea pig placenta (measured probably in the trophoblastic cells) are caused by the difference between the intracellular and extracellular concentration of potassium. The transport of ions, for example Na+, across the trophoblastic cells, has to surmount an electrochemical concentration gradient.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Archives of gynecology and obstetrics 242 (1987), S. 591-592 
    ISSN: 1432-0711
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1433-8580
    Keywords: Dopamine ; isolated perfused rat kidney ; direct stimulation of α-receptors by DA ; NA-depletion ; histochemical and electron microscopical observations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In the isolated, perfused kidney of untreated and catecholaminedepleted rats (by 6-hydroxydopamine and reserpine), dopamine (DA) caused a dose-dependent increase in vascular resistance which could be prevented by prior blockade of the α-adreno-receptors. The DA-induced vasoconstriction thus appears to be due to a direct stimulation of α-receptors in the kidney rather than an indirect sympathomimetic effect through release of noradrenaline from local adrenergic nerve terminals. The effectiveness of the chemical sympathectomy accomplished with 6-hydroxydopamine and reserpine was evaluated by chemical, histochemical and electron microscopical methods.
    Type of Medium: Electronic Resource
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