Effect of whole gut irrigation solutions on gastrointestinal smooth muscle activity

It has been suggested that whole gut irrigation (WGI), which is a preparation method for large bowel surgery or colonoscopy, increases gastrointestinal motility by creating a gastrocolic reflex. An experimental study was performed to evaluate the effect of different WGI solutions on gastrointestinal smooth muscle activity.

Thirty Wistar albino rats weighing 200 to 250 g were enrolled in the study. After anesthetization with thiopental sodium (50 mg/kg), proximal ileum, terminal ileum, and colon segments were removed via median laparotomy to obtain a control group. Four different groups (n = 6) were designated as having WGI with saline solution (SS), lactated Ringer's solution (RL), polyethylene glycol (PEG), and dibasic sodium phosphate (DNP). Bowel cleaning was performed by infusing solutions at a rate of 2 mL/min via gastric tube, until the stool was cleared. After completing the bowel cleaning, 2 cm of tissues were removed and suspended in Tyrode solution in an isolated organ bath with a resting tension of 1 g, to obtain carbachol and potassium chloride (KCl) responses.

The mean bowel cleaning times were 87.5 +/- 9.35, 81.6 +/- 9.83, 86.6 +/- 11.6, and 85.0 +/- 0.0 minutes in SS, RL, PEG, and DNP groups, respectively. The total amounts of solutions needed for cleaning were 156.67 +/- 21.6, 195.0 +/- 20.0, 197.5 +/- 32.8, and 70.0 +/- 0.0 mL, respectively. Although there was no difference in cleaning time between the groups, the amount of solution required was significantly less in the DNP group (P = .02). In the proximal ileum segments, though there was no difference in carbachol responses between groups, KCl responses were significantly increased in the RL group (P < .05). When we evaluated the terminal ileum responses, carbachol responses were significantly increased in RL and PEG groups (P = .011) and decreased in the DNP group (P = .049). The KCl responses were also significantly increased in the RL group with respect to the other groups (P < .05). Colon segments showed no difference in contractile responses with respect to different WGI solutions (P > .05, analysis of variance, post hoc Dunn's test).

The different WGI solutions demonstrated no significant differences in colon contractions. The increased contractile responses in the proximal and terminal ileum segments after WGI with RL may be related to the electrolyte composition of RL. Although the lower amount of DNP solution required to achieve bowel cleaning seems to be an advantage, the decreased ileal contractions can be assessed as a disadvantage of DNP irrigations.