Changes in the neuronal activity of the ganglia of the myenteric plexus upon transmural electrical stimulation

The neuronal activity of the myenteric plexus is recorded extracellularly in preparations isolated from cat duodenum, using tungsten microelectrodes with tip diameter 5-10 micrometers and resistance 0.5-2 mOhms. Transmural electrical stimulation after Burn and Rand (1960) with a pair of platinum electrodes is applied at a distance of 1 cm proximally from the place of recording. The responses of the single-spike neurones and of the erratic burst-type neurones to transmural electrical stimulation (series of impulses with frequency 1-20 Hz, duration of impulses 0.1-0.5 ms and suprathreshold current intensity) depend on the background neuronal activity. Thus, in the case of weak activity, stimulation with a frequency of 1-8 Hz results in activation of both types of neurones. A particularly high neuronal activity, stimulation with the same frequency results in inhibition. Transmural electrical stimulation does not change the character of the activity of steady burst-type neurones.