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  • 1975-1979  (5)
  • Dopamine  (3)
  • Locus coeruleus  (2)
  • Uptake  (2)
  • Electrical Stimulation
  • 1
    Digitale Medien
    Digitale Medien
    Uptake of dopamine into fractions of pig caudate nucleus homogenates (1975)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 287 (1975), S. 181-190 
    Details
    ISSN: 1432-1912
    Schlagwort(e): Caudate Nucleus ; Dopamine ; Ouabain ; Reserpine ; Prenylamine ; Uptake
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Homogenates of the caudate nucleus of the pig were submitted to differential centrifugation. The 20 000 g and 80 000 g fractions were isolated and a part of them was osmotically shocked. The highest dopamine content per mg protein was found in the intact 80 000 g fraction. Incubation experiments with the intact and the osmotically shocked fractions at 25°C revealed that the particles of the intact 20 000 g fraction took up dopamine; the influx of the amine was not enhanced by addition of ATP and magnesium to the incubation medium. On the other hand after osmotic shock the uptake of dopamine into the particles of this fraction was greatly enhanced by addition of ATP and magnesium. The uptake of dopamine into the particles of both intact and osmotically shocked 80 000 g fractions was likewise enhanced by ATP and magnesium. The uptake in all fractions was not influenced by ouabain. The influx of dopamine into the particles of the intact 80 000 g fraction was competitively inhibited by reserpine (K i 0.96×10−8 M) and prenylamine (K i 1.74×10−8 M). It is concluded that the intact 20,000 g fraction contains intact synaptosomes; the uptake of dopamine is independent of the presence of ATP and magnesium. The shocked 20 000 g fraction and the 80 000 g fractions contain synaptic vesicles; the uptake of dopamine into these vesicles is enhanced by ATP and magnesium.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00510449
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  • 2
    Digitale Medien
    Digitale Medien
    In vivo release of endogenous GABA in the cat hypothalamus (1979)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 308 (1979), S. 143-147 
    Details
    ISSN: 1432-1912
    Schlagwort(e): Hypothalamus ; GABA release ; Superfusion ; Electrical stimulation ; Potassium chloride ; Locus coeruleus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The posterior hypothalamus of anaesthetized cats was superfused with artificial cerebrospinal fluid through a push-pull cannula and the release of endogenous GABA from the hypothalamus into the superfusate was studied. The resting release of GABA varied rhythmically, since phases of high rate of release were separated from each other by phases of low rate of release. The time interval between two adjacent phases of high rate of release was about 70 min. Electrical stimulation of the posterior hypothalamus with the tip of the cannula enhanced the rate of release of GABA in a frequency-dependent way. Superfusion of the hypothalamus with CSF which contained a high concentration of potassium and a low concentration of sodium increased the rate of release of GABA; this effect was dependent on the presence of calcium ions in the superfusing fluid. Pretreatment of the cats with reserpine reduced the levels of GABA in hypothalamus and rest of brain and the concentration of GABA in the superfusate as well. Stimulation of the locus coeruleus with a bipolar electrode elicited an increased release of GABA in the hypothalamus.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00499056
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  • 3
    Digitale Medien
    Digitale Medien
    In vivo release of endogenous catecholamines in the hypothalamus (1979)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 308 (1979), S. 137-142 
    Details
    ISSN: 1432-1912
    Schlagwort(e): Hypothalamus ; Superfusion ; Catecholamine release ; Electrical stimulation ; Locus coeruleus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The posterior hypothalamus of anaesthetized cats was superfused with a push-pull cannula and the release of the endogenous catecholamines noradrenaline, adrenaline and dopamine was determined in the superfusate. The rate of release of the three catecholamines followed an ultradian rhythm, the time interval between two adjacent phases of high rate of release being about 70 min. Pretreatment of the animals with reserpine decreased the levels of catecholamines in the hypothalamus and rest of the brain and reduced their rate of release into the superfusate. Hypothalamic superfusion with superfusing fluid of high concentration of potassium and low concentration of sodium enhanced the rate of release of noradrenaline and adrenaline; this effect was abolished when the hypothalamus was superfused with calcium-free solution. Electrical stimulation of the locus coeruleus ipsilateral to the superfused hypothalamus increased the release of noradrenaline and adrenaline, stimulation of the contralateral locus coeruleus enhanced the release of noradrenaline, adrenaline and dopamine. In both cases, the rate of release of adrenaline was enhanced to a lesser extent than the rate of release of noradrenaline. The release of noradrenaline and adrenaline was increased to a higher extent on stimulation of the ipsilateral locus coeruleus than on stimulation of the contralateral one.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00499055
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  • 4
    Digitale Medien
    Digitale Medien
    Uptake of serotonin, gamma-aminobutyric acid and histamine into synaptic vesicles of the pig caudate nucleus (1975)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 287 (1975), S. 191-204 
    Details
    ISSN: 1432-1912
    Schlagwort(e): Synaptic Vesicles ; Dopamine ; GABA ; Serotonin ; Histamine ; ATP
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Dopamine-containing vesicles were isolated from the caudate nucleus of the pig by differential centrifugation and incubated with 14C-serotonin (14C-5-HT), 14C-gamma-aminobutyric acid (14C-GABA), 14C-dopamine or 14C-histamine. At 25°C the uptake of 14C-5-HT and 14C-GABA was enhanced by ATP and magnesium. The Km for the uptake of 14C-5-HT in the presence of ATP and magnesium was 0.67×10−6 M, that of 14C-GABA 1.33×10−4 M. 14C-Histamine was also taken up into the vesicles but its uptake was not influenced by ATP and magnesim. The ATP-magnesium-dependent uptake of 14C-5-HT and 14C-GABA was abolished at 0°C. At 37°C the accumulation of 14C-GABA in the presence of ATP and magnesium reached a steady state after 20 min, while the accumulation of 14C-5-HT reached a maximum after 2.5 min of incubation and then gradually declined. Osmotic lysis of the vesicles followed by sonication abolished the enhanced uptake of 14C-GABA, 14C-5-HT and 14C-dopamine in the presence of ATP and magnesium. Determination of the endogenous contents of the vesicles revealed 14.6 pmoles per mg protein for 5-HT and 22.7 nmoles per mg protein for GABA. It is concluded that the caudate nucles preparation used in this study contains not only dopamine-storing vesicles able to take up biogenic amines but also GABA-containing vesicles which take up GABA by an ATP-magnesium-dependent process.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00510450
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  • 5
    Digitale Medien
    Digitale Medien
    Uptake of tyramine into synaptic vesicles of the caudate nucleus (1977)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 300 (1977), S. 25-30 
    Details
    ISSN: 1432-1912
    Schlagwort(e): Synaptic vesicles ; Uptake ; Dopamine ; Tyramine ; Reserpine ; Filtration
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Synaptic vesicles isolated from the caudate nucleus of the pig were preincubated with reserpine, serotonin or tyramine at concentrations which caused a 90% inhibition of the ATP-Mg2+-dependent uptake of 14C-dopamine. The preincubated vesicles were sedimented by centrifugation and resuspended in drug-free buffer. The vesicles were incubated with 14C-dopamine in the presence or in the absence of ATP-Mg2+; at the end of the incubation period they were separated from the incubation medium by centrifugation. The inhibitory effect of reserpine on the ATP-Mg2+-dependent uptake of 14C-dopamine was slightly diminished, that of serotonin reduced while the inhibitory effect of tyramine was abolished. Hence, tyramine seems to be more easily removable than the other substances. In another series of experiments the vesicles were incubated with 3H-tyramine and immediately separated by filtration through membrane filters. Addition of ATP-Mg2+ enhanced the uptake of 3H-tyramine. The Km of the ATP-Mg2+-dependent uptake of 3H-tyramine was 1.4×10−7 M, the Vmax 29.2 pmoles/mg protein/min. At 0°C the uptake of 3H-tyramine in the absence of ATP-Mg2+ was reduced, that in the presence of ATP-Mg2+ abolished. Incubation of the vesicles with 3H-dopamine revealed K m and V max values similar to those previously found when the vesicles were isolated from the incubation medium by centrifugation. Incubation in the presence of reserpine inhibited the ATP-Mg2+-dependent uptake of 3H-tyramine (IC50 1.4×10−8 M) and 3H-dopamine (IC50 4.1×10−8 M). The results demonstrate that tyramine is taken up into the vesicles by a process which is dependent on ATP-Mg2+ and temperature. Failure of previous attempts to prove an ATP-Mg2+-dependent uptake of tyramine when the vesicles were separated by centrifugation seems to be due to release of the accumulated tyramine during the centrifugation procedure.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00505076
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