Characterization of the very late cardiosympathetic A-reflex in high-mesencephalic cats.

In unanaesthetized mid-collicular decerebrate cats, stimulation of low-threshold afferents running in the inferior cardiac nerve can evoke in renal nerve a long-latency reflex response, which is able to reduce or overcome the inhibition developing after the late response. The spatial and temporal summation have great importance in generating this very late response (VLR). Increasing the stimulus intensity and the frequency of the impulses, using short trains or a previous A + C tetanic stimulation of the segmental inputs considerably increased the chance of the VLR overcoming the late inhibition.

[Noradrenaline suppression of the spinal efferent component of the pressor reflexes].

Noradrenaline applied to the dorsal surface of spinal cord segments C6-T1 suppressed the pressor components of the blood pressure reflexes evoked by stimulation of radial nerve afferents in anesthetized cats. Noradrenaline applied to spinal cord segments L4-S1 suppressed pressor reflexes elicited by stimulation of tibial nerve afferents. The increase in noradrenaline concentration from 0.

[Reactions of arterial pressure to sciatic nerve A-fiber impulses in decerebrate and spinal frogs].

Contrary to mammals, cutting of the spinal cord on the caudal part of the first segment in high-decerebrated nonanesthetized frogs does not evoke any statistically significant changes in blood pressure or lead to the depression of pressor responses to sciatic nerve A fibres stimulation. The intensity of the responses remains unchanged following cordotomy when stimulation frequency is low and increases when stimulation frequency is high. The results are believed to corroborate the conception on the predominant role of spinal shock in the depression of somato-sympathetic reflex reactions in cordotomized mammals.

[Arterial pressure reactions due to A- and C-afferent discharges of the sciatic nerve in anesthetized and unanesthetized frogs].

The role of impulses of sciatic nerve A- and C-afferents in the reflex changes of arterial pressure was studied in anesthetized and unanesthetized frogs. In anesthetized frogs, A-fiber excitation(A beta- and "fast" A delta-fiber subgroups) evoked depressor reflexes, impulses of "slow" A delta-fibers decrease them and C-fiber excitation evoked pressor reflexes. In unanesthetized frogs, only pressor reflexes can be evoked.