VASOMOTOR DISCHARGES IN TOAD'S SPLANCHNIC NERVE

Abstract

1. Tonic vasomotor discharges were observed in the toad's splanchnic nerve, which were sometimes grouped synchronously with the heart beat.
2. Electrical stimulation of various nerves evoked first an increase of the discharge (excitation) and thereafter a silent period (inhibition).
3. After the medulla oblongata had been removed the inhibition was no longer observed and stimulation effected the excitation phase only. After further removal of the upper spinal cord stimulation did not evoke any response in the splanchnic nerve, though the tonic discharge was still observable.
4. Almost similar discharge patterns and responses were observed with the medulla oblongata and spinal cord (the medullospinal preparation) which had been excised with the splanchnic nerve and kept in a Ringer's bath under aeration.
5. On the basis of the above stated results the automaticity of the segmental vasomotor center and the location of the higher vasomotor centers of this animal are discussed.