Aim: To evaluate and characterize motility patterns from small intestinal gut segments depending on different perfusion media and pressures.
Methods: Experiments were carried out in a custom designed perfusion chamber system to validate and standardise the perfusion technique used. The perfusion chamber was built with a transparent front wall allowing for optical motility recordings and a custom made fastener to hold the intestinal segments. Experiments with different perfusion and storage media combined with different luminal pressures were carried out to evaluate the effects on rat small intestine motility. Software tools which enable the visualization and characterization of intestinal motility in response to different stimuli were used to evaluate the videotaped experiments. The data collected was presented in so called heatmaps thus providing a concise overview of form and strength of contractility patterns. Furthermore, the effect of different storage media on tissue quality was evaluated. Haematoxylin-Eosin stainings were used to compare tissue quality depending on storage and perfusion mode.
Results: Intestinal motility is characterized by different repetitive motility patterns, depending on the actual situation of the gut. Different motility patterns could be recorded and characterized depending on the perfusion pressure and media used. We were able to describe at least three different repetitive patterns of intestinal motility in vitro. Patterns with an oral, anal and oro-anal propagation direction could be recorded. Each type of pattern finalized its movement with or without a subsequent distension of the wavefront. Motility patterns could clearly be distinguished in heatmap diagrams. Furthermore undirected motility could be observed. The quantity of the different patterns varies and is highly dependent on the perfusion medium used. Tissue preservation varies depending on the perfusion medium utilized, therefore media with a simple composition as Tyrode solution can only be recommended for short time experiments. The more complex media, MEM-HEPES medium and especially AQIX(®) RS-I tissue preservation reagent preserved the tissue much better during perfusion.
Conclusion: Perfusion media have to be carefully chosen considering type and duration of the experiments. If excellent tissue quality is required, complex media are favorable. Perfusion pressure is also of great importance due to the fact that a minimum amount of luminal pressure seems to be necessary to trigger intestinal contractions.
Keywords: Motility; Organ perfusion; Pharmacological testing; Small intestine; Visualization.