ELECTROPHYSIOLOGICAL CLASSIFICATION OF SUBMUCOSAL PLEXUS NEURONS IN THE JEJUNUM OF THE NEWBORN PIG

Intracellular recordings were made from the internal and external subm ucosal ganglia of the porcine small intestine and neuronal properties were classified using two existing schemes for guinea-pig enteric neur ones. In the first analysis, 77% of cells were designated as Type 4 si nce they were a heterogeneous population of neurones with the overlapp ing properties of S/Type 1 and AH/Type 2. The simplicity and usefulnes s of the second classification scheme was due to its emphasis on a sin gle electrophysiological event, namely, the long-lasting after-hyperpo larization (AH) following the action potential. Eighty-eight percent o f the cells studied were thus categorized as either AH (with an AH) or S (without an AH). All S neurones displayed fast synaptic potentials in response to stimulation of interganglionic fibre strands. AH neuron es were subdivided into two groups dependent on whether they received fast synaptic inputs. Only by employing the second scheme of classific ation were differences in the neuronal characteristics and synaptic pr ofiles between the two submucosal plexuses detected. It is concluded t hat the S and AH system of classification is the most appropriate meth od for the analysis of intracellular recordings from submucosal neuron es in the porcine small intestine. (C) 1996 Elsevier Science Inc.