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  • 1
    Electronic Resource
    Electronic Resource
    Functional development of the parasympathetic innervation of the sino-auricular node in newborn rabbits, cats and guinea pigs (1983)
    Springer
    Pflügers Archiv 398 (1983), S. 73-77 
    Details
    ISSN: 1432-2013
    Keywords: Ontogenesis ; Autonomic nervous system ; SA-node ; Rabbit ; Cat ; Guinea pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects of supramaximal vagus nerve stimulation on heart rate were studied in newborn rabbits, cats and guinea pigs. The analysis of the stimulus-effect curve revealed that the carlier proposed relationship: logI f/I o=H·f (I o is the steady state PP-interval before andI f during stimulation,f is the stimulus frequency, andH the slope of the line) accurately summarizes the relation in rabbits, while with minor deviations it also holds for newborn cats and guinea pigs. Thus, the vagus effect for each nerve and animal is characterized by the slope of the line,H. In rabbits and cats the vagus effect decreased during the first postnatal week to about 1/3 and 1/5 of the initial value at birth. Guinea pigs, however, did not show such a postnatal change of the vagus effect. In comparison with rabbits and cats these animals are born at a relatively late ontogenetic stage. Therefore, we hypothesized that the decrease in vagus effect is related to the stage of development and occurs mainly before birth in this species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00584717
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Quantitative effect of vagal stimulation on heart interval in newborn and older rabbits (1971)
    Springer
    Pflügers Archiv 325 (1971), S. 61-76 
    Details
    ISSN: 1432-2013
    Keywords: Neonatal Heart ; Vagal Stimulation ; Sino-Auricular Node ; Heart Interval ; Neonatales Herz ; Vagusreizung ; Sinusknoten ; Herz-Intervall
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In two groups of young rabbits, aged 0–5 and 9–23 days, the effect on the heart interval of stimulation of the right and left vagal nerves separately was investigated at frequencies of 1, 2, 4, 8 and 16 stimuli per second. Up to and including 8 stimuli per second, this is well described by log10 (I f /I o )=Hf, orI f =I o L f =I o e hf , whereI o andI f are the heart intervals before and during stimulation respectively at frequencyf, L is a lengthening factor,H=log10 L andh=2.3026 H. Thus each increase in vagal stimulation multiplies the heart interval by a constant factor. the response as defined by H were estimated for both right and left vagal nerves in 15 rabbits, and right or left only in 7 others. The responses varied considerably in individual rabbits and were much larger for almost all in the younger group. The effects of right compared with left stimulation, and of deviations of observed from fitted interval ratios, are studied in detail. Some other mathematical forms given in the literature for the response curves are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00587492
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    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Negative power functions of time in pharmacokinetics and their implications (1985)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 13 (1985), S. 309-346 
    Details
    ISSN: 1573-8744
    Keywords: clearance curves ; pharmacokinetics ; tracer kinetics ; homogeneous compartments ; multiexponentials ; negative powers of time ; gamma functions ; random walks with drift ; distributions of time intervals ; Inverse Gaussian distributions ; convolutions ; models
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract When a clearance curve in pharmacokinetic studies- and in tracer kinetics in general — is well fitted by a sum of negative exponentials of time, in very many cases the data would also be well fitted over much or all of the same period by a function of time consisting mainly of a negative power or by a gamma function. There are also instances where two such power functions can be observed in the same clearance curve. Examples are given from numerous reanalyses of published results. These facts have not been explained, except as being fortuitous, by any existing theory or model based on two or more homogeneous compartments. Theoretical and practical implications are outlined and some general recipes are put forward with a view to replacing multicompartmental analysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01065658
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    Paper (German National Licenses)
    Fulltext
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