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  • Chemical Engineering  (2)
  • Adrenoceptors  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 348 (1993), S. 643-649 
    ISSN: 1432-1912
    Keywords: Epicardial mapping ; Class-III-antiarrhythmic drugs ; Adrenoceptors ; Propranolol ; β-blockers ; Norepinephrine ; Dispersion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Isolated perfused spontaneously beating rabbit hearts were treated with increasing concentrations of norepinephrine (0.01, 0.1, 0.5 μmol/l) either alone or in presence of propranolol (0.1 μmol/l). For analysis of the epicardial activation and repolarization process and epicardial mapping (256 unipolar leads) was performed. For each electrode the activation and repolarization time was determined. From these data the “breakthrough-points” (BTP) of epicardial activation were determined. At each electrode an activation vector (VEC) was calculated giving direction and velocity of the local excitation wave. The beat similarity of various heart beats (under NE) compared to control was evaluated by determination of the percentage of identical BTP and of similar VEC (deviation ≤5°). Moreover at each electrode the local activation recovery interval (ARI) and its standard deviation (of 256 leads, dispersion, DISP) were determined. Norepinephrine alone (0.01, 0.1, 0.5 μmol/l) led to an increase in left ventricular pressure, heart rate and DISP with concomittant frequency dependent reduction in ARI, and to changes in the epicardial activation pattern (reduction in BTP, VEC). We found that in the presence of propranolol (0.1 μmol/l) norepinephrine prolonged ARI and reduced ARI-dispersion. This effect was not due to changes in heart rate. The disturbing effects on the activation pattern were dimished. These effects could be prevented by pretreatment with 1 μmol/l prazosine. From these results we conclude, that norepinephrine prolongs the relative action potential duration via stimulation of α1-adrenoceptor and enhances cellular coupling. Thus, the antiarrhythmic properties of propranolol may at least in part be due to an unmasking of class III like norepinephrine effects and additional reduction in dispersion.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 36 (1990), S. 1433-1438 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 31 (1991), S. 1461-1466 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A model for predicting the contact duration, force, indentation, and displacement under impact has been developed for impact of a composite laminated plate with a hemispherical indenter. The governing equations were first proposed and then solved with the initial conditions along with the peak force condition. An expression forr each parameter has been obtained in a simple expression through straightforward derivation. Both static and dynamic tests have been conducted. Ten impact tests were conducted using a weight drop tower tester. Comparison between the, model predictions and the experimental data on the impact duration and impulse are provided, and were found to be within 14% for all tests involved. Comparison of the impact force-history also shows good accord.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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