Regulation of SGLT1 expression in response to Na+ intake

In the chicken intestine, the reduction in Na+ intake led to a decrease in the transport of alpha-methyl-D-glucoside in the ileum (reduction of 42%) and in the rectum (51%). These reductions were reversed within 24 h after resalination and were inversely correlated to the changes in aldosterone plasma concentration. The reduction in intestinal hexose transport in the low Na+-fed animals was due to a decrease in the number of Na+-dependent D-glucose cotransporters (SGLT1) in the rectum (46%) and in the ileum (38%). Northern blot analysis showed that specific SGLT1 mRNA was expressed in the jejunum, ileum, and rectum. The amount of SGLT1 mRNA was the same in all intestinal regions and was not affected by Na+ intake, supporting the view that the effects of dietary Na+ on intestinal hexose transport involve posttranscriptional regulation of SGLT1. This study suggests that changes in SGLT1 expression may be involved in the homeostasis of Na+.