[Responses of enterometasympathetic neurons to transmural electric stimulation].

Transmural electrical stimulation evokes a multicomponent response in the enterometasympathetic ganglion, the response consisting of early low-amplitude APs and late single AP or bursts of APs. Some of the neurons developed a high-amplitude antidromic spike following the stimulation. Application of ganglio-blocking agent hexonium (10(-6) g/ml), solutions with high magnesium concentration (up to 10 mM) and high-frequency stimulation (30 Hz) led to disappearance of single APs but not the bursts of APs. This suggests that some components of the response are synaptically evoked in ortho- and antidromic stimulations. The remaining spikes reflect conduction of excitation along continuous nerve fibers. Transmural electrical stimulation leads to either increase or decrease in the spontaneous firing rate of neurons except the cells generating stable burst-like firing. Reasons and significance of these changes are discussed.