Summary
In decerebrate or urethane-anesthetized cats with pneumothorax and neuromuscular blockade, evoked responses in the efferent splanchnic nerve, elicited by electric shocks to medullary regions, were studied as samples of sympathetic outflow related to vasocontrictor activity and were analyzed with an average-response computer.
Evoked responses of short latency were obtained from the classical medullary vasomotor sites. 1. Single shocks in the pressor region of the dorsolateral rostral medulla (level of apex of ala cinerea), where high-frequency stimulation produces marked blood pressure rises, evoked excitatory responses (wave of increased activity) having a modal latency of 40 msec and durations of 50–200 msec. 2. Single shocks in the depressor region of the ventromedial medullary reticular formation (level of the obex), where high-frequency stimulation produces marked blood pressure falls, evoked inhibitory responses (decrease of activity) having a modal latency of 30 msec and durations of 20–30 msec. The consistently shorter latency of the depressor point response suggests that this inhibition of splanchnic discharge is carried via descending pathways to spinal preganglionic neurons.
By delivery of shocks in the ventrolateral white matter of the cervical spinal cord, and measurement of differences between latencies of responses from different levels, it was estimated that the travel velocity in the cervical cord for the evoked excitatory response is about 5 m/sec.
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This work was supported by U.S. Public Health Service Grants NB-03970, NB-06590, NB-5304, and MH-6418.
Most of the material in this paper was included in a dissertation submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy at Albert Einstein College of Medicine, New York, N.Y.
Career Scientist of the Health Research Council of the City of New York (Contract I-292).
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Gootman, P.M., Cohen, M.I. Evoked splanchnic potentials produced by electrical stimulation of medullary vasomotor regions. Exp Brain Res 13, 1–14 (1971). https://doi.org/10.1007/BF00236427
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DOI: https://doi.org/10.1007/BF00236427