Dynamic responses in small intestinal mucus: Relevance for the maintenance of an intact barrier

• Small intestinal mucus is a complex secretion with complex dynamic behavior.
• Viscoelastic measurements of SI mucus vary with sample mechanical history.
• SI mucus strain hardens in both small and large deformation regimes.

Mucus in the small intestine acts as both a lubricant and a barrier to reduce mucosal exposure to damaging agents, and must perform these functions in a highly mechanically dynamic environment, both in terms of luminal shear and gut wall contractility. Here we investigate the dynamic responses of ex vivo pig small intestinal mucus to applied shear of different magnitudes over different timescales. At low levels of applied stress of 1 Pa, which is of the order of magnitude of that induced by gut wall contractility, the mucus demonstrates stress hardening responses to the applied deformation. This hardening behavior is lost at higher levels of applied stress. Such hardening behavior is likely to contribute to the ability of small intestinal mucus to maintain a barrier at the mucosal surface in the mechanically dynamic gut environment.

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