Effect of Ethanol Exposure on Slow Wave Activity and Smooth Muscle Contraction in the Rat Small Intestine

Background: Ethanol ingestion causes a variety of gastrointestinal disturbances including motility alterations. Slow wave propagation coordinates gastrointestinal motility, and abnormal slow wave activity is thought to contribute to motility disorders. To date, however, little is known about the effect of acute ethanol on motility disturbances associated with slow wave activity. Aim: To investigate the effect of ethanol on small intestine slow wave activity. Methods: Segments (3–5 cm long) were isolated from the rat duodenum, jejunum, and ileum and mounted in an organ bath superfused with a normal Tyrode solution or with 1, 3, or 5 % ethanol containing Tyrode. The electrical activities were recorded using an array of 121 extracellular electrodes, and motility recordings were performed using a digital video camera. Results: The frequency and amplitude of slow wave activity were not altered at 1, 3, or 5 % ethanol concentrations, but a significant drop in velocity was found at 3 and 5 % ethanol. Furthermore, inexcitable areas appeared in a dose-dependent manner. Slow wave was sometimes also seen to propagate in a circular fashion, thereby describing a reentrant loop. Finally, in all duodenal, jejunal, and ileal segments, ethanol inhibited contractions and became fully quiescent at 3–5 %. Conclusions: These studies for the first time demonstrate that ethanol significantly inhibits slow wave and spike activity in a dose-dependent manner and could also initiate reentrant activities. Intestinal contractions were also inhibited in a dose-dependent manner. In conclusion, ethanol inhibits both slow wave activity and motor activity to cause ethanol-induced intestinal disturbances.