Effect of lipopolysaccharide on rabbit small intestine muscle contractility in vitro: role of prostaglandins.

The purpose of this study was to investigate the effect of lipopolysaccharide (LPS) on spontaneous contractions and acetylcholine (ACh) induced contractions of rabbit intestinal segments in vitro, with two different protocols: intestinal segments isolated from LPS-treated rabbits and intestinal segments incubated with LPS. The frequency of spontaneous movements decreased significantly in LPS-treated rabbits at 2 microg kg-1 in the duodenum and 20 microg kg-1 in the duodenum, jejunum and ileum. LPS (0.2 microg kg-1) reduced significantly the ACh contractions (10-6 mol L-1) in the duodenum (61%), jejunum (48%) and ileum (21%). Indomethacin (1, 5 and 10 mg kg-1) administered 15 min before LPS (0.2 microg kg-1) antagonized the LPS effects on the ACh-induced contractions. Prostaglandin (PG)E2 (8 microg kg-1) inhibited significantly the frequency of spontaneous contractions in the ileum and reduced the ACh-induced contractions in the three segments, mimicking the LPS effects. The amplitude and frequency of contractions in rabbit intestinal segments previously incubated with LPS (0.03, 0.3, 3 and 30 microg mL-1) were not modified with respect to the control. The ACh-induced contractions (10-4 mol L-1) were significantly reduced after 90 min of incubation with LPS. The inhibition of LPS (0.3 microg mL-1) was 43% in the duodenum, 35% in the jejunum and 17% in the ileum. Indomethacin added before LPS blocked the effect of LPS on the ACh-induced contractions in the duodenum, jejunum and ileum. These results show that LPS decreases intestinal contractility in rabbits and suggest that PGs are implicated in these actions.