[Characteristics of the late A-response of vasoconstrictor neurons in cats decerebrated at different brain stem levels].

In cats decerebrated at the level of the rostral border of the midbrain (the mesencephalic animals) and in those decerebrated at different pontine levels, including the ponto-bulbar junction level, and the most rostral parts of the medulla oblongata (the "pontine" animals), or more caudal parts (the bulbar animals), single stimulus of the tibial nerve A-fibres elicited a late response in the renal nerve consisting of excitatory and inhibitory components. The excitatory component was relatively small or absent in 53% of the "pontine" animals, in 42% of the mesencephalic animals, and in 18% of the bulbar animals. The "pontine" animals had the most active and most excitable system of the inhibitory component generation. However, the signs of a comparatively more powerful inhibitory component of the A-afferent action of the vasoconstrictor neurones in the "pontine" animals were not as constant as to explain completely the transition of somatic A-afferent hypertensive reflexes into the hypotensive ones, occurring in separating the ponto-bulbar structure and the rostral parts of the medulla oblongata from the mesencephalon.