Cross-talk along gastrointestinal tract during electrical stimulation: effects and mechanisms of gastric/colonic stimulation on rectal tone in dogs

Gastric electrical stimulation (GES) has been shown to alter motor and sensory functions of the stomach. However, its effects on other organs of the gut have rarely been investigated. The study was performed in 12 dogs implanted with two pairs of electrodes, one on the serosa of the stomach and the other on the colon. The study was composed of two experiments. Experiment 1 was designed to study the effects of GES on rectal tone and compliance in nine dogs compared with colonic electrical stimulation (CES). Rectal tone and compliance were assessed before and after GES or CES. Experiment 2 was performed to study the involvement of sympathetic pathway in 8 of the 12 dogs. The rectal tone was recorded for 30-40 min at baseline and 20 min after intravenous guanethidine. GES or CES was given for 20 min 20 min after the initiation of the infusion. It was found that both GES and CES reduced rectal tone with comparable potency. Rectal compliance was altered neither with GES, nor with CES. The inhibitory effect of GES but not CES on rectal tone was abolished by an adrenergic blockade, guanethidine. GES inhibited rectal tone with a comparable potency with CES but did not alter rectal compliance. The inhibitory effect of GES on rectal tone is mediated by the sympathetic pathway. It should be noted that electrical stimulation of one organ of the gut may have a beneficial or adverse effect on another organ of the gut.