Regional capacities of gastrointestinal absorption and lymphatic transport for lipid-soluble dyes in rats.

Abstract

The regional differences in the capacities of absorption and lymphatic transport for lipid-soluble dyes, Sudan Blue and Oil Red XO, from oil-in-water emulsions were investigated in the gastrointestinal tract of rats. The absorptive capacity was the highest in duodenum, followed by jejunum, ileum and large intestine,absorptive capacity was the lowest in stomach. This was compatible with the regional absorption of vehicle oil, triolein. Lymphatic transport of Sudan Blue was seen only in duodenal and jejunal regions. This was supported by lymphatic staining. Lipid-soluble dyes are taken up into the intestinal epithelial cells from emulsions by an energy-independent process, since little or no inhibition was observed in various pretreated duodenum preparation except the decrease of lymphatic transport observed in acetone washed intestine. Severe villi damage was observed light microscopically when pretreated with high acetone concentrations (80%), Sudan Blue absorption was significantly decreased in this case. The normality of macromorphological structure of mucosal surface probably is important for the absorption of lipid-soluble drugs from oil-in-water emulsions.