Hormonal regulation of chicken intestinal NHE and SGLT-1 activities

The effects of aldosterone and arginine vasotocin (AVT) on intestinal Na+/H + exchange (NHE) and Na+-sugar cotransport (SGLT-1) activities have been in vestigated using brush-border membrane vesicles isolated from Hubbard chick en small and large intestines, and they were compared with those induced by either Na+ depletion or dehydration. Na+ depletion was induced by feeding the chickens with either a low- or a high-Na+ diet for either 0.5, 1, 2, 4, or 8 days. Ileal and colonic NHE2 activity increased with the duration of the Na+ depletion, whereas that of intestinal SGLT-1 decreased, reaching a plateau after 2 days of treatment. Three-hour incubation of the intestine w ith aldosterone produced the same effects on NHE activity as does Na+ deple tion, without altering SGLT-1 activity. However, 3-h incubation of the inte stine with AVT increased intestinal SGLT-1 activity, without affecting inte stinal NHE activity. It is concluded that aldosterone regulates apical ilea l and colonic NHE2 activity, whereas that of SGLT-1 is regulated by AVT.