AR Chikh-Issa G Charpin C Dumas P Nicol D Pansu M Descroix-Vagne

ligated loops in response to different luminal saline loads: NaCl concentration varied from 150-0 mM, solutions being made isoosmotic with mannitol. The contact delay was 60 min. An exponential relationship was found between water, Na and CI movements and the initial saline concentration. Maximal absorption was obtained with 150 mM NaCi, and was significantly higher in the duodenum than in the jejunum and ileum. The NaCl concentration for which water, Na, and CI movements were null was = 70 mM NaCI in the duodenum and jejunum, 41 mM for Na and 18 mM for CI in the ileum. The water efflux induced by the 0-mM NaCl test solution was maximal in the duodenum (1.5 ± 0.2 ml/h) and decreased in the jejunum (0.8 ± 0.1 ml/h) and ileum (0.3 ± 0.1 ml/h) as did sodium, chloride and nonchloride anion efflux. These data support the functional heterogeneity of the small intestine regulating the water and ion exchange in response to luminal saline load, the main difference being connected with the efflux capacity of the mucosa, decreasing from the duodenum to the jejunum and ileum.