Effects of oat β‐glucan on bile salts absorption across porcine intestinal mucosa using Ussing chamber system (372.4)

Abstract

Soluble dietary fibres (SDFs) such as oat β‐glucan decrease blood triglycerides and cholesterol. The current lead hypothesis is that this is caused by slowing the re‐absorption of bile salts (BS), possibly by SDF causing an increase in the barrier properties of the unstirred water layer lining the epithelium of the small intestine (SI) by adhering and/or penetrating between the microvilli, thus hindering the uptake of BS. Pigs used as a human model were fed on a control diet (n=6) and a diet containing 10% oat βG (n=6) for 27‐29 d. The SI was sectioned into proximal, mid jejunum and terminal ileum. Each section was prepared and mounted in triplicate into 18 Ussing chambers. Glycodeoxycholate (GDC) and fluorescein isothiocyanate‐labelled dextran (FITC‐dextran (4kDa), to check for tissue integrity) with or without oat βG were added to the mucosal side of the chambers and samples for GDC and FITC‐dextran analyses taken from the serosal side, every 20 min for 80 min. Fresh tissue and tissues after diffusion experiment in the Ussing chambers were fixed for microscopic comparison. The preliminary GDC results show that (1) there is a decrease in the amount of GDC diffusing across the epithelium with the βG diet compared to the control diet, (2) ileal passage is different to passage across the jejunum, and (3) added βG to the mucosal side causes a reduction in the absorption of GDC in the terminal ileum of pigs from the control diet and a reduction in both the proximal jejunum and terminal ileum for tissues from the βG diet. The Ussing chamber seems to be a useful system to test hypotheses on how SDF reduces the diffusion of BS across the epithelium of the SI and thereby helps to understand the mechanisms and properties of SDF required for lipid management and consequent reduction in risk for cardiovascular disease.Grant Funding Source: Supported by ARC Centre of Excellence in Plant Cell Walls