Effect of magnetic stimulation on the electromechanical activity of the rectum: an experimental study

We recently studied the effect of sacral magnetic stimulation (MS) on the rectal mechanical activity. The current communication investigates its effect on the rectal electric activity. Twelve mongrel dogs (weight 15.2 +/- 3.2 kg, 7 male, 5 female) were anesthetized, the abdomen was opened, and three electrodes were sutured to the rectal serosa. The rectal pressure was recorded by a manometric catheter. The effect of sacral MS on the rectal electric activity and pressure was recorded before and after anesthetization of the sacral skin. Stimulation parameters were set at 70% intensity, 20 Hz frequency, and 1 to 5 s burst activity. Sacral MS of the empty and full rectum effected a significant increase of the rectal electric activity and pressure as well as a decrease of the rectal neck (anal canal) pressure. MS of the anesthetized sacral skin produced no significant changes in the rectal electromechanical activity or the anal canal pressure. MS of the saline-injected sacral skin produced rectal and anal changes similar to those without saline injection. In conclusion, MS presumably produces its effect on the rectum by increasing the rectal electric activity. It might provide a more convenient method for rectal evacuation than electrostimulation through implanted electrodes. The procedure is simple, easy, and noninvasive.