Trophic effect of short chain fatty acids on mucosal handling of ions by the defunctioned colon.

Sodium and water absorption were measured in defunctioned loops of colon of dogs either in the presence or in the absence of the bacterial fatty acid, n-butyrate. In freshly defunctioned colonic loops n-butyrate enhanced sodium absorption twofold (P less than 0.05) and promoted sodium absorption for 48 h. In the absence of n-butyrate, defunctioned loops lost the ability to absorb sodium and water within 48 h. Pre-treatment of colonic loops with fatty acids for 3 h significantly diminished (P less than 0.05) sodium and water losses into the colonic lumen compared with loops pre-treated with saline only. Butyrate was absorbed at a steady rate even when no sodium was absorbed. Results suggest that fatty acids act on the colonic mucosa to exert a trophic effect on absorption of sodium. This trophic effect determines the efficiency of absorption of ions and could have clinical implications in the genesis of postoperative diarrhoea.