Electrophysiology of porcine myenteric neurons revealed after vital staining of their cell bodies. A preliminary report.

Due to practical limitations in visualizing and getting access to the ganglionic components of large mammals, electrophysiology of the enteric nervous system has been restricted mainly to small laboratory animals, more particularly the guinea-pig. The use of the vital dye 4-(4-diethylaminostyry1)-N-methylphyridinium iodide (4-Di-2-ASP), however, overcomes some of these difficulties. A 20-min incubation period with this dye, followed by a minimum period of 4 h in Krebs solution, suffices to stain the neuronal cell bodies, permitting selection of a neuron and positioning of the microelectrode for impalement and recording. The method has been applied to pig ileum and guinea-pig large and small bowel myenteric neurons. Impalements of untreated guinea-pig myenteric neurons were compared with those of 4-Di-2-ASP-pretreated ones. According to our preliminary data, the staining did not suppress the expression of apparently normal electrophysiological activity. Moreover, the procedure permitted impalement and recording of myenteric plexus neurons in pig ileal tissue with a rate of success equalling blind impalement on guinea-pig tissue. In contrast with formerly published results whereby staining of the neuronal cell bodies only occurred when the cells had been chemically damaged, our experiments suggest a possible correlation between fluorescence and cell viability.