Fig. 5.

Model of intestinal fluid movement in health and in acute cholera treated with ORS. (Width of arrows provides approximation of fluid movement; values presented are per 24 h.) a In health, the major fraction of fluid entering the small intestine is absorbed with approximately 2 l reaching the colon where all but less than 200 ml is also absorbed.b In cholera, there is significant small intestinal fluid secretion secondary to active Cl secretion and inhibition of NaCl absorption (see Fig. 1) resulting in enhanced ileo-cecal flow; in addition, colonic Na-Cl and fluid absorption is reduced resulting in up to 7 l of diarrhea per day. c Administration of ORS does not alter active Cl secretion but enhances fluid absorption by stimulating active Na absorption (via a cAMP-independent process) in the small intestine correcting dehydration but only modestly reducing ileo-cecal flow. Colonic fluid absorption is not altered. d Administration of HAMS (a resistant starch)-ORS results in identical changes in the small intestine but in the colon HAMS is fermented to SCFA that stimulates Na absorption (also via a cAMP-independent process) resulting in further rehydration and a substantial reduction in diarrhea