Effects And Mechanisms Of Colonic Electrical Stimulation On Colonic Transit In Rats

Part I Effects of Colonic Electrical Stimulation with Trains of Short Pulses and Long Pulses on Colonic Transit in ratsBackground: Gastrointestinal electrical stimulation has been proposed for the treatment of gastrointestinal motor disorders. However, little is known about potential roles of colonic electrical stimulation (CES).Objective: The aim of our study was to evaluate the effects of CES with trains of short pulses and CES with long pulses on colonic transit in conscious rats.Methods: Male rats were equipped with colonic electrodes for stimulation and a catheter in the colon. Colonic transit was assessed by calculating the output of phenol red from the anus every 10-min for 90-min in 3 randomized sessions, including saline without CES; saline with CES of trains of short pulses; and saline with CES of long pulse.Results: 1. CES with trains of short pulses significantly enhanced colonic transit. The colonic emptying was 57.3±6.1% in the control session and 81.9±4.6 % in the session of CES with trains of short pulses at 90 min, reflecting a 43% increase.2. CES with long pulses didn't promote colonic transit. The colonic emptying was 57.3±6.1% in the control session and 51.6±6.6% in the session of CES with long pulses. There is nonsignificant difference between the two sessions. Conclusions: Colonic electrical stimulation with trains of short pulses has an excitatory effect on colonic transit. Colonic electrical stimulation with long pulses doesn't have promotive effect on colonic transit.Part II Effects and Mechanisms of Colonic Electrical Stimulation with Trains of Short Pulses on Colonic Transit in RatsBackground: Gastrointestinal electrical stimulation has been proposed for the treatment of gastrointestinal motor disorders. However, little is known about potential roles of colonic electrical stimulation (CES).Objective: The aim of our study was to evaluate the effects and mechanisms of CES with trains of short pulses on colonic transit in conscious rats.Methods: Male rats were equipped with colonic electrodes for stimulation and a catheter in the colon. Colonic transit was assessed by calculating the output of phenol red from the anus every 10-min for 90-min in 6 randomized sessions, including saline with or without CES; nitric oxide synthesis blocker, L-NNA, with or without CES; and atropine with or without CES. Results: 1. CES with trains of short pulses significantly enhanced colonic transit. The colonic emptying was 57.3±6.1% in the control session and 81.9±4.6 % in the session of CES with trains of short pulses at 90 min, reflecting a 43% increase.2. L-NNA delayed colonic transit compared with saline and prevented the accelerative effect of CES with trains of short pulses on colonic transit.3. Atropine delayed colonic transit compared with saline and did not prevent the accelerative effect of CES with trains of short pulses on colonic transit.Conclusions: Colonic electrical stimulation with trains of short pulses has an excitatory effect on colonic transit and this excitatory effect may be mediated via the nitrergic pathway, not the cholinergic pathway.