NUTRIENT REGULATION OF HUMAN INTESTINAL SUGAR TRANSPORTER (SGLT1) EXPRESSION

Background-The activity of most intestinal nutrient transporters is ad aptively regulated by the type and amounts of nutrients entering the i ntestinal lumen. The concentration and activity of the intestinal Na+/ glucose cotransporter (SGLT1) are regulated by dietary sugars in most animal species. The activity and abundance of SGLT1 in biopsy specimen s removed from human jejunal regions exposed to, and having limited ac cess to, luminal nutrients have been measured and compared. Aims-To st udy the effects of luminal nutrients on the expression of SGLT1 in the human intestine. Patient and Methods-Brush border membrane vesicles ( BBMV) were prepared from biopsy specimens removed from the intestine o f a 50 year old man who had developed a high output jejunal fistula, a nd adjacent mucosal fistula, a condition present for 12 months after s urgery for a strangulated hernia. BBMV prepared from intestine exposed to luminal nutrients, and from dysfunctional intestine with a limited exposure to nutrients, were used to measure Na+ dependent glucose tra nsport and abundance of SGLT1 protein. Results-The levels of SGLT1 act ivity and abundance in the BBMV prepared from control biopsy specimens were similar to those found in BBMV prepared from the intestine of he althy individuals. BBMV from the dysfunctional intestine, exposed to l imited levels of luminal nutrients, had reduced levels of SGLT1 activi ty. This reduction in SGLT1 activity and abundance was above that asso ciated with any villus atrophy, as assessed by the abundance/activity of lactase and villin concentrations. Conclusions-These data indicate that the activity and expression of SGLT1 in human intestine is mainta ined by the presence of luminal nutrients.