Effect of ATP applied to the mucosa on myenteric S neurons and circular muscle. ATP (1 mm) was applied to mucosa directly circumferential from the impalement. Calibrations inA applies to all traces.A, Representative voltage traces from two S neurons; thedotted lines indicate RMP. Top, ATP evoked a burst of fast EPSPs, two of which reach threshold for AP generation. Bottom, ATP evoked a slow EPSP-like depolarization that evoked many APs. B, Voltage traces from a single circular muscle cell. Top, Electrical stimulation of the mucosa, directly circumferential to the recording site, evoked a biphasic inhibitory junction potential (RMP of −48 mV).Bottom, Application of ATP to the same site on the mucosa evoked a biphasic inhibitory event, similar to that evoked electrically (RMP of −55 mV). ES, Electrical stimulation.