Effect of pentagastrin, secretin and cholecystokinin on intestinal water and sodium absorption in the rat.

To test the effect of pentagastrin, secretin and cholecystokinin on intestinal absorption of water and sodium, duodenal , jejunal and ileal loops were prepared in situ in fasted rats, filled with NaCl solution containing 14C PEG and 22Na as markers. Hormones were given by intracardiac injection, the content of the loops was collected 1 h later. In control rats, water and sodium absorption were 5, 30 and 50% of the injected quantities in duodenum, jejunum and ileum, respectively. Pentagastrin (ICI; 1.25, 5 and 20 microgram/100 g) increased the duodenal absorption of water and sodium and decreased the ileal absorption. Secretin (GIH; 0.17, 0.85 AND 3.5 CU/100 g) induced a duodenal secretion and decreased the ileal absorption. Cholecystokinin (GIH; 1, 4, 8 AND 12 IDU) induced a duodenal secretion and decreased the ileal absorption at the lowest dose while the effect disappeared with higher doses. As previously known, the gastrointestinal hormones modulate intestinal absorption of water and sodium. This study indicates that the effect depends on dose and segment under study.