In vitro transport of β-lactoglobulin across the jejunum of lactose-fed rats

Abstract

Summary &horbar; Changes in protein absorption through the intestinal mucosa occur with aging and might reflect modifications in enterocyte membrane characteristics. We have observed that bovine [3-lactoglobulin (P-LG) was efficiently transported across the small intestine of adult rats in vitro and that 12-16% of the absorbed protein was recovered intact or as large hydrophobic peptides. Ten percent lactose-feeding resulted in decreased tissue conductance and significantly reduced (-58%, P < 0.05) j3-LG transport across rat small intestinal mucosa. The amounts of j3-LG absorbed, either as amino acids and peptides or as intact protein, were reduced to the same extent. Therefore, the effect of lactose feeding might be related to a decrease in protein endocytosis at the brush-border level, rather than to reduced protein transport across tight junctions. intestine / (3-lactoglobulin / lactose / transport / rat

Transport of β-lactoglobulin and α-lactalbumin in enterocyte-like Caco-2 cells

“…R-Lg is also believed to be resistant to peptic and chymotryptic digestion (Reddy et al, 1988) and to play a role as a carrier of small, lipid-soluble molecules (Papiz et al, 1986;Brown etal, 1988). Both (Stern and Walker, 1984;Gardner, 1988;MarconGenty et al, 1989;Huneau and Tome, 1990;Tome, 1992, 1994). Since the Caco-2 cell line grown on permeable filters forms a polarized monolayer, it has been proposed as an intestinal epithelium model (Pinto etal, 1983;Hidalgo etal, 1989).…”