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  • blood pressure reflexes  (3)
  • Springer  (3)
  • American Physical Society
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  • Springer  (3)
  • American Physical Society
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  • 1
    Electronic Resource
    Electronic Resource
    The rhombencephalon and vasomotor reflexes to impulses in somatic A-fibers (1978)
    Springer
    Bulletin of experimental biology and medicine 86 (1978), S. 1421-1424 
    Details
    ISSN: 1573-8221
    Keywords: decerebration ; somatic afferents ; blood pressure reflexes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Cats were decerebrated so that the medulla preserved its connections with a greater or lesser part of the pons, after which they were immobilized with flaxedil or succinylcholine and the response of their arterial blood pressure (BP) to volleys of impulses in various subgroups of fibers of the tibial nerve (frequency of volleys 10 sec−1) was investigated. Impulses in Aβ + Aδ1-afferents and the most excitable fraction of Aδ2-afferents lowered BP in all animals. Application of impulses in all Aδ2-afferents potentiated the fall in BP in 79% of the experiments and led to a rise in BP in only 21% of the experiments. The addition of impulses in Aδ3-fibers to the afferent flow either did not change the mean decrease in BP or led to a small or sometimes more considerable increase in BP. The critical factor producing a sharp reduction in the pressor reflexes or their replacement by depressor reflexes was the integrity of the structures of the pontobulbar junction and the most rostral part of the medulla. This region of the hindbrain thus contains formations causing tonic depression of the excitatory action of impulses in somatic A-afferents on vasoconstrictor neurons and which thereby unmask the existence of an inhibitory component of their action on these neurons. In unanesthetized cats this action of hindbrain structures is depressed tonically by the mesencephalon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00800273
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  • 2
    Electronic Resource
    Electronic Resource
    Characteristics of late vasoconstrictor A-response in cats after decerebration at different levels of the brain stem (1979)
    Springer
    Bulletin of experimental biology and medicine 87 (1979), S. 88-92 
    Details
    ISSN: 1573-8221
    Keywords: decerebration ; somatosympathetic responses ; blood pressure reflexes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Single stimulation of A-fibers of the tibial nerve in cats decerebrated at the rostral border of the mesencephalon (mesencephalic animals) at various levels of the pons, including the region of the pontobulbar junction, and the most rostral levels of the medulla (pontine animals), or rather more caudally to this region (bulbar animals), evoked a late response in the renal nerve, consisting of excitatory and inhibitory components. In 53% of experiments on pontine animals, 42% of experiments on mesencephalic animals, but only 18% of experiments on bulbar animals the excitatory component of the response was small or even absent. The system generating the inhibitory component of the response was most active and most excitable in the pontine cats. However, features indicating relative potentiation of the inhibitory component of action of impulses in A-afferents on vasoconstrictor neurons in the pontine animals were not sufficiently constant to account for the switch from hypertensive reflexes to impulses from somatic A-afferents into hypotensive, taking place after disconnection of the structures of the pontobulbar junction and rostral levels of the medulla from the mesencephalon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00833955
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  • 3
    Electronic Resource
    Electronic Resource
    Blood pressure reflexes to stimulation of tibial nerve a fibers in mesencephalic and bulbar cats (1977)
    Springer
    Bulletin of experimental biology and medicine 84 (1977), S. 1381-1385 
    Details
    ISSN: 1573-8221
    Keywords: decerebration ; somatic afferents ; blood pressure reflexes ; general anesthesia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The role of the various subgroups of A fibers of the tibial nerve (pulse frequency of electrical stimulation 10/sec) in the formation of reflex changes in blood pressure (BP) was investigated in unanesthetized cats with total transection of the brain stem at the level of the pontomedullary junction (bulbar animals) or at the rostral border of the mesencephalon (mesencaphalic animals), and also in anesthetized cats with an intact brain. The lowest thresholds for the reflexes were found in anesthetized animals with an intact brain, the highest in bulbar cats. Excitation of A fibers in anesthetized cats with an intact brain evoked only depressor reflexes. In some bulbar and mesencephalic animals only pressor reflexes appeared. In the experiments of this group excitation of fibers with a conduction velocity of over 15 m/sec in mesencephalic cats evoked reflexes of near maximal strengths, whereas in bulbar cats excitation of thinner A fibers also was necessary. In unanesthetized animals disconnection of the suprabulbar structures thus lowers the sensitivity of the central mechanisms of vasomotor regulation to impulses in lowthreshold A fibers. No such effect was found in another group of experiments in which depressor reflexes appeard in response to stimulation of fast-conducting A fibers only. In these experiments, if slower A fibers also were stimulated, the reflexes became pressor but the difference between their magnitude in the bulbar and mesencephalic cats was not signicant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00801101
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