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  • 1
    ISSN: 1432-2013
    Keywords: Flow-autoregulation ; Ventricular function ; External heart work ; Myocardial oxygen consumption ; Efficiency ; Pyruvate decarboxylation ; Noradrenaline
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Cardiac performance and some parameters of glycolytic and oxidative metabolism were analyzed in isolated perfused guinea pig hearts performing pressure-volume work. Perfusion medium was an oxygenated Krebs-Henseleit bicarbonate buffer (pH 7.4) which contained glucose and physiological concentrations of pyruvate and insulin. The pressure-flow relationship in the coronary vascular bed indicated autoregulation of coronary flow. Left ventricular function was influenced by aortic pressure (Pa) and venous filling pressure (Pv) in accordance with the Frank-Starling principle, i.e. stroke work increased as a function of Pa or Pv to a certain maximum and then decreased. Myocardial oxygen consumption (MVO2), on the other hand, was linearly correlated with Pa and Pv, respectively, over the entire pressure range. Efficiency of the left ventricle, therefore, increased to an optimum (16%) and decreased at higher pressures. Myocardial contents of glycogen, ATP and creatine phosphate were not markedly influenced by a change in Pa or Pv.l-Noradrenaline (0.08 μM, NA) stimulated stroke work and MVO2 at a all Pv tested; efficiencies reached physiologic values (21%) at high volume loads. The increased MVO2 was associated with an acceleration of pyruvate decarboxylation and lactate release up to 10- and 15-fold, respectively, at elevated but physiological NA concentrations (0.2 μM). Our results demonstrate that the isolated perfused working guinea pig heart compares favourably with the non-failing Starling heart-lung preparation and hearts in situ, as far as coronary function, left ventricular performance and oxidative metabolism are concerned.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 571 (1989), S. 21-28 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: CsB3H8: Crystal Structure and Upgrading of the SynthesisA simple method for a high yield preparation of NaB3H8 and CsB3H8 respectively is described.The single crystal structure determination of CsB3H8 shows, that the general arrangement of cations Cs+ and anions (B3H8)- corresponds to a rocksalt structure with an orthorhombic distortion. No disorder of the fluxional (B3H8)-anion, as frequently observed in compounds with complex cations, can be detected. The study indicates that the triangular anion has Cs symmetry with two asymmetric hydrogen bridges and three BH2 groups. The two hydrogen bridged B—B connectivities are significantly shorter (179 pm) than the non-bridged one (185 pm).
    Notes: Ein Eintopfverfahren zur Herstellung von NaB3H8 bzw. CsB3H8 in hoher Ausbeute wird beschrieben.Wie die Einkristallstrukturanalyse von CsB3H8 zeigt, entspricht die Anordnung der Kationen Cs+ und Anionen (B3H8)- Anionen, wie häufig in entsprechenden Verbindungen mit komplexen Kationen, beobachtet. Das (B3H8)-Anion besitzt im CsB3H8 Cs-Symmetrie mit zwei asymmetrischen H-Brücken und drei terminalen BH2-Gruppen. Die beiden H-überbrückten Seiten des gleichschenkligen Dreiecks aus drei B-Atomen sind signifikant kürzer (179 pm) als die nicht überbrückte Seite (185 pm).
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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