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  • 1
    Electronic Resource
    Electronic Resource
    Über die subcelluläre Verteilung von 3,3′-Dimethyl-4,4′-diacetyldiphenylbisguanylhydrazon im Meerschweinchenherzen (1969)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 263 (1969), S. 417-426 
    Details
    ISSN: 1432-1912
    Keywords: Bisguanylhydrazone ; Digitalis Like Activity ; Heart Muscle ; Subcellular Distribution ; Guinea Pig ; Bisguanylhydrazon ; herzglykosidartig wirkende Substanz ; Herz ; subcelluläre Verteilung ; Meerschweinchen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Meerschweinchenherzen wurden 0,5—30 min isoliert mit 3,3′-Dimethyl-4,4′-diacetyldiphenylbisguanylhydrazon (BG 60) perfundiert, anschließend homogenisiert und durch Differentialzentrifugation in Kern-Membran-Mitochondrien-, Mikrosomen- und Überstands-Fraktion getrennt. Im Homogenat und in den einzelnen Fraktionen wurde die BG 60-Konzentration und der Proteingehalt bestimmt. Außerdem wurden Herzen von Tieren unmittelbar nach Infusion der Substanz oder 7 Tage danach in gleicher Weise aufgearbeitet. Bei BG 60-Zusatz zum Homogenat lag die höchste auf Protein bezogene Konzentration in der Mitochondrien-Fraktion vor. Der BG 60-Gehalt der Mitochondrien wurde mit zunehmender Perfusionsdauer von demjenigen der Mikrosomen übertroffen. Eine ähnliche Akkumulation von BG 60 in der mikrosomalen Fraktion wurde nach Infusion der Substanz gefunden. Der BG 60-Gehalt der Partikel-Fraktion geht der positiv inotropen Wirkung der Substanz nicht parallel.
    Notes: Summary Isolated guinea pig hearts were perfused with the digitalis like substance 3,3′-dimethyl-4,4′-diacetyldiphenylbisguanylhydrazone (BG 60) for 0.5 to 30 min. The hearts were homogenized and separated by differential centrifugation into nuclear/cell membrane, mitochondrial, microsomal, and supernatant fractions. The hearts of animals given intravenous BG 60 were studied immediately after the end of infusion or 7 days later. The BG 60 and the protein contents of the homogenate and the different fractions were determined. When BG 60 was added to the homogenate, the highest concentration relative to protein content was found in the mitochondria. With increasing time of perfusion the BG 60 concentration of the microsomal fraction exceeded that of the mitochondrial fraction. A similar accumulation of BG 60 in the microsomal fraction was found after the infusion of the substance. The content of BG 60 in the particulate fractions does not parallel the positive inotropic effect.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00538775
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  • 2
    Electronic Resource
    Electronic Resource
    Heart rate deflection related to lactate performance curve and plasma catecholamine response during incremental cycle ergometer exercise (1995)
    Springer
    European journal of applied physiology 70 (1995), S. 175-179 
    Details
    ISSN: 1439-6327
    Keywords: Heart rate deflection ; Lactate performance curve ; Plasma catecholamines ; Cycle ergometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The correlation between the behaviour of the heart rate/work performance (f c W) curve and blood lactate ([la]b) and plasma adrenaline/noradrenaline concentrations ([A]/[NA]) during incremental cycle ergometer exercise was investigated. A group of 21 male sports students was divided into two groups: group I, with a clear deflection of thef c W curve; group II, without or with an inverse deflection of thef c W curve. The aerobic threshold (Thaer) and the lactate turn point (LTP) were defined. Between Thaer and maximal work performance (f c W max) the behaviour of thef c W curve as well as the behaviour of [la−]b and [A]. [NA] were described mathematically. Thef c, systolic blood pressure (BPS),W, [la−]b, [A] and [NA] at rest, Thaer, LTP,f c W max, after 3 and 6 min of recovery (Re3/Re6) were calculated. A significant difference between the two groups could only be detected forf c at LTP, Re3 and Re6 (P 〈 0.05). No significant, correlation could be found between individualf c W-behaviour and individual time course of [la−]b, [A] and [NA]. However, a significant correlation was visible between [la−/W-behaviour and individual catecholamine response. These results and the fact that the different flattening at the top of thef c W curve was related to diminished stress-dependent myocardial function led us to the conclusion that it is possible that sympathetic drive is not directly involved in mechanisms of regulation between load dependentf c and myocardial function. In addition, individualf c W behaviour was independent of BPS andW max, or individual conditions of energy supply.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00361546
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Correlation between inflection of heart rate/work performance curve and myocardial function in exhausting cycle ergometer exercise (1993)
    Springer
    European journal of applied physiology 67 (1993), S. 385-388 
    Details
    ISSN: 1439-6327
    Keywords: Cycle ergometry ; Myocardial function ; Left ventricular ejection fraction ; Radionuclide ventricular scintigraphy ; Inflection of heart rate/performance curve
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The heart rate/work performance (f c/W) curve is usually S-shaped but a flattening at the top is not always seen. By means of radionuclide ventricular scintigraphy, the left ventricular ejection fraction (LVEF) of 15 sports students was investigated. The behaviour of the f c/W curve during cycle ergometry with increasing exercise intensities was examined. During exercise, the LVEF showed a distinct initial increase reaching roughly constant values at stress levels below-maximum, and sometimes even falling again. The inflections of the f c/W curve and left ventricular ejection fraction/performance curve (LVEFPC) were calculated from a second degree polynomial fit. From this function, the slopes of the tangents at the points of aerobic threshold and maximum performance were calculated together with the differences of the angles as a measure of the f c/W curve and LVEFPC inflections. It follows that the f c/W curve inflection became less pronounced or was even absent altogether when the decrease in LVEF towards the end of the ergometer exercise became more distinct. A significant negative correlation was found between the existence and extent of the f c/W curve inflection and the stress-dependent myocardial function, expressed as the inflection of the LVEFPC (P〈0.01, r=0.673). Thus, it would seem that the absence of a f c/W curve inflection was related to a diminished stress-dependent myocardial function.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00376453
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    Paper (German National Licenses)
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