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  • 68.55  (1)
  • Parasympathetic nervous system  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Ouabain enhances release of acetylcholine in the heart evoked by unilateral vagal stimulation (1986)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 333 (1986), S. 7-12 
    Details
    ISSN: 1432-1912
    Keywords: Heart ; Parasympathetic nervous system ; Ouabain ; Release of acetylcholine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The aim of the study was to elucidate peripheral effects of ouabain on the parasympathetic innervation of the heart, effects that could contribute to the experimentally and clinically well established “vagal effect of cardiac glycosides”. The experiments were carried out with ouabain concentrations of 3×10−7 and 10−6 mol/l, which were considered “therapeutic”, as they increased force of contraction and did not elicit arrhythmias in incubated chicken atria. In atrial preparations of chickens and guinea-pigs the negative chronotropic and inotropic effects of acetylcholine (ACh) were not altered by 3×10−7 mol/l ouabain. Resting efflux of ACh from perfused chicken hearts was increased by ouabain from 10 to a maximum of 30 pmol/g min, whereas release of ACh evoked by bilateral vagal stimulation at 3 or 20 Hz for 1 min was unchanged (resting release subtracted). In contrast, release of ACh caused by unilateral vagal stimulation was augmented by ouabain up to 200% of the control. Release by unilateral stimulation (80 pmol/g; 20 Hz) was calculated for each experiment by averaging the releases evoked by consecutive stimulation of the right and left nerves. Ouabain infused for 90 min did not alter the tissue content of ACh (5.5 nmol/g). Within 2 days after unilateral (left) vagal transsection (denervation of cardiac ganglia) the release of ACh evoked by stimulation of the intact nerve (20 Hz) increased from about 80 to 200 pmol/g, whereas the release from the lesioned nerve markedly declined. One day after denervation, ouabain had lost the ability to facilitate the release of ACh evoked by stimulation of the intact nerve, whereas the release by stimulation of the lesioned nerve was still increased. It is concluded that ouabain at “therapeutic” concentrations increased resting release of ACh but did not influence the mechanism of action potential-evoked release of ACh. The effect of exogenous ACh on sinus node activity was not enhanced by ouabain. The observation that ouabain increased release of ACh caused by unilateral, but not by bilateral vagal stimulation was explained by an increase in the number of activated postganglionic neurons arising from those (contralateral) ganglia that received a subthreshold input from the stimulated vagus nerve.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00569652
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Optical gate realization with thin CdS films (1991)
    Springer
    Applied physics 53 (1991), S. 539-546 
    Details
    ISSN: 1432-0630
    Keywords: 42.65 P ; 42.65 G ; 68.55 ; 19.08 ; 78.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A spray deposited thin (6 μm) CdS film laser induced optical device (LIOD) was studied experimentally and theoretically. The all optical bistable (all-OB) and the hybrid bistable (HB) features at 210 K were investigated. It is shown for the first time that the observation of equal contrasted all-OB and HB loops is possible in thin CdS films. The slope of the all-OB loops were calculated with a new theoretical model which is established on the thermal enhanced shift of the absorption edge and the transmitted light equilibrium condition. A good agreement with the experiments is found. Furthermore, it is pointed out that the electron life time determines the fashion and the contrast of the HB loops. In this context the proof is furnished that the maximal possible HB loops is observed. Finally, the influence of Joule's heat on OB and HB is demonstrated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00331543
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    Paper (German National Licenses)
    Fulltext
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