Background/aims: morphine is known to inhibit cholinergic contractions of the guinea pig small intestine. This has been compared to the human small intestinal innervated longitudinal muscle in the current study.
Methods: cholinergic primary contractions of human small intestinal longitudinal strips were evoked by electrical field stimulation (EFS; 0.5- 5 Hz in the presence of purinergic and nitrergic blockers or 5 Hz without pretreatment) and recorded isotonically in organ bath experiments. Guinea pig small intestinal segments were also studied.
Results and conclusion: neurogenic cholinergic contractions of human preparations were unaffected by morphine (1, 2 or 10 micromol/l). Longitudinal contractions of the guinea pig ileum were concentration-dependently suppressed by morphine (0.1-10 micromol/l). It is concluded that myenteric neurons supplying the longitudinal muscle of the human small intestine are much less sensitive to morphine than those of the guinea pig.
2010 S. Karger AG, Basel.