Synaptic potentials recorded from neurones of the submucous plexus of guinea-pig small intestine.

1. Intracellular recordings have been made from neurones lying in the submucous plexus of guinea-pig mid small intestine. 2. Most neurones in this plexus receive an extensive excitatory input which could be abolished by tubocurarine. 3. A proportion of neurones also received a single inhibitory input which was activated by transmural stimulation. 4. Some of the characteristics of the inhibitory potentials evoked by transmural stimulation are described. 5. The observations are discussed in relation to the concept of descending excitation (Hirst, Holman & McKirdy, 1975).