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  • 1995-1999  (3)
  • 1950-1954
  • 1945-1949
  • 1995  (3)
  • Programmed electrical stimulation  (2)
  • 5-HT1A  (1)
  • 1
    ISSN: 1432-1912
    Schlagwort(e): Dispersion ; Refractoriness ; ATP-sensitive potassium channel ; Canine ; Programmed electrical stimulation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The proarrhythmic effects of the ATP-sensitive potassium channel modulators cromakalim (n = 10; 0.01 to 0.3 mg/kg i.v.), glibenclamide (n = 10; 0.3 to 10 mg/kg i.v.) or volume equivalents of vehicle (n = 10) were evaluated in post-infarcted anaesthetised dogs. Dogs were anaesthetised, subjected to an anterior-apical myocardial infarction, and allowed to recover. At 7.4 ± 0.7 days post infarction, animals were anaesthetised again, electrophysiologic measurements (effective refractory periods, QT-intervals and ventricular fibrillation thresholds) were taken, and animals were tested for arrhythmias using a programmed electrical stimulation protocol. Only animals that did not have programmed electrical stimulation-inducible arrhythmias were used. Ventricular fibrillation thresholds were determined twice, once before the first dose then after the last dose of drug. At the end of the experiment, animals were subjected to ligation of the left circumflex coronary artery and survival was measured over the next two hours. Cromakalim significantly increased heart rate and decreased blood pressure. Although cromakalim significantly reduced effective refractory periods, it neither increased electrical dispersion, as determined by the standard deviation or coefficient of variance of the effective refractory period, nor did it enhance inducibility (0 out of 10 in both vehicle and cromakalim treated animals), change ventricular fibrillation thresholds, or reduce sudden death survival relative to vehicle. Glibenclamide did not increase electrical dispersion, but slightly increased the incidence of programmed electrical stimulation-induced arrhythmias (3 out of 10), and lowered ventricular fibrillation thresholds values. However, these changes were not statistically significant. Glibenclamide did not significantly affect survival relative to vehicle. Infarct sizes of the left ventricle were not statistically different among groups. In conclusion, cromakalim and glibenclamide did not affect dispersion of refractoriness. Glibenclamide did demonstrate a propensity towards proarrhythmic activity. However, the doses needed to observe proarrhythmic activity with glibenclamide were significantly higher than those needed for clinical treatment of hyperglycemia.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1432-1912
    Schlagwort(e): Key words Dispersion ; Refractoriness ; ATP-sensitive potassium channel ; Canine ; Programmed electrical stimulation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  The proarrhythmic effects of the ATP-sensitive potassium channel modulators cromakalim (n=10; 0.01 to 0.3 mg/kg i.v.), glibenclamide (n=10; 0.3 to 10 mg/kg i.v.) or volume equivalents of vehicle (n=10) were evaluated in post-infarcted anaesthetised dogs. Dogs were anaesthetised, subjected to an anterior-apical myocardial infarction, and allowed to recover. At 7.4±0.7 days post infarction, animals were anaesthetised again, electrophysiologic measurements (effective refractory periods, QT-intervals and ventricular fibrillation thresholds) were taken, and animals were tested for arrhythmias using a programmed electrical stimulation protocol. Only animals that did not have programmed electrical stimulation-inducible arrhythmias were used. Ventricular fibrillation thresholds were determined twice, once before the first dose then after the last dose of drug. At the end of the experiment, animals were subjected to ligation of the left circumflex coronary artery and survival was measured over the next two hours. Cromakalim significantly increased heart rate and decreased blood pressure. Although cromakalim significantly reduced effective refractory periods, it neither increased electrical dispersion, as determined by the standard deviation or coefficient of variance of the effective refractory period, nor did it enhance inducibility (0 out of 10 in both vehicle and cromakalim treated animals), change ventricular fibrillation thresholds, or reduce sudden death survival relative to vehicle. Glibenclamide did not increase electrical dispersion, but slightly increased the incidence of programmed electrical stimulation-induced arrhythmias (3 out of 10), and lowered ventricular fibrillation thresholds values. However, these changes were not statistically significant. Glibenclamide did not significantly affect survival relative to vehicle. Infarct sizes of the left ventricle were not statistically different among groups. In conclusion, cromakalim and glibenclamide did not affect dispersion of refractoriness. Glibenclamide did demonstrate a propensity towards proarrhythmic activity. However, the doses needed to observe proarrhythmic activity with glibenclamide were significantly higher than those needed for clinical treatment of hyperglycemia.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Psychopharmacology 117 (1995), S. 41-48 
    ISSN: 1432-2072
    Schlagwort(e): 8-OH-DPAT 8(-hydroxy-2(di-n-propylamino)tetralin ; (+)WAY 100,135 ; 5-HT1A ; Median raphe Dorsal raphe ; Prepulse inhibition ; Startle ; Serotonin
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Recent studies have implicated central serotonergic systems in the modulation of prepulse inhibition (PPI), an operational measure of sensorimotor gating, which has been used to identify gating deficits in psychiatric disorders, such as schizophrenia, Huntington's disease, and obsessive compulsive disorder. Both serotonin (5-HT) releasers and agonists at 5-HT1A, 5-HT1B, and 5-HT2 receptors reduce PPI in the rat. The present experiments demonstrate that the disruption of PPI in rats induced by the systemic administration of the 5-HT1A agonist, 8-OH-DPAT (8-hydroxy-2(di-n-propylamino)tetralin; 0.2 mg/kg), can be attenuated by the novel, selective 5-HT1A antagonist (+)WAY 100,135, (20.0 mg/kg),N-tert-butyl-3-(4-(2-methoxyphenyl)-piperazin-1-yl)-2-phenyl-propanamide. Further experiments addressing the central site of action of 8-OH-DPAT revealed that the microinjection of 8-OH-DPAT (5.0 µg/0.5 μl) into either the median raphe nucleus (MR) or dorsal raphe nucleus (DR) disrupts PPI. The reduction in PPI produced by intra-raphe microinjections of 8-OH-DPAT was prevented by a systemic injection of (+)WAY 100,135. These results support the hypothesis that somatodendritic 5-HT1A autoreceptors within the midbrain raphe subserve the PPI-disruptive effects of systemically administered 8-OH-DPAT. The decrement in PPI after intra-raphe infusions of a high dose of 8-OH-DPAT, however, was substantially less than the decrement in PPI after systemic administration of the drug. Hence, sites in addition to the somatodendritic autoreceptors may also play an important role in 8-OH-DPAT-induced disruption of PPI. Together with previous reports that 5-HT releasers and other 5-HT agonists also disrupt PPI, the results support the hypothesis that the serotonergic system modulates PPI through multiple receptor and anatomical systems.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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