Role of colonic short-chain fatty acid transport in diarrhea.
Short-chain fatty acids (SCFA) are the major anion in stool and are synthesized from nonabsorbed carbohydrate by the colonic microbiota. Nonabsorbed carbohydrate are not absorbed in the colon and induce an osmotically mediated diarrhea; in contrast, SCFA are absorbed by colonic epithelial cells and stimulate Na-dependent fluid absorption via a cyclic AMP-independent process involving apical membrane Na-H, SCFA-HCO(3), and Cl-SCFA exchanges. SCFA production represents an adaptive process to conserve calories, fluid, and electrolytes. Inhibition of SCFA synthesis by antibiotics and administration of PEG, a substance that is not metabolized by colonic microbiota, both result in diarrhea. In contrast, increased production of SCFA as a result of providing starch that is relatively resistant to amylase digestion [so-called resistant starch (RS)] to oral rehydration solution (RS-ORS) improves the efficacy of ORS and represents an important approach to improve the effectiveness of ORS in the treatment of acute diarrhea in children under five years of age.
Binder
Henry J
HJ
Departments of Internal Medicine and Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT 06520, USA. henry.binder@yale.edu
D000818:Animals; D001693:Biological Transport, Active / Q000502:physiology; D003106:Colon / Q000378:metabolism*; D000242:Cyclic AMP / Q000502:physiology; D003967:Diarrhea / Q000378:metabolism*; D005232:Fatty Acids, Volatile / Q000378:metabolism* / Q000494:pharmacology; D005440:Fluid Therapy; D006801:Humans; D007408:Intestinal Absorption; D009997:Osmotic Pressure; D012964:Sodium / Q000378:metabolism; D017923:Sodium-Hydrogen Exchangers / Q000502:physiology
D005232:Fatty Acids, Volatile; D017923:Sodium-Hydrogen Exchangers; D012964:Sodium; D000242:Cyclic AMP