Absorption of Lactic Acid from an Isolated Intestinal Segment in the Intact Rat

Summary Lactic acid absorption was studied in anesthetized rats by perfusing isolated segments of small intestine or colon with sodium lactate-1-14C for 2 hours. The concentration and pH of the perfusate were varied. Absorption was maximum at pH 2.8, near the pK of lactate, and minimum at physiologic pH. Absorption was directly related to concentration of the lactate perfused and it was not affected by a metabolic inhibitor. The jejunum was the site of maximum absorption. Absorbed lactate was metabolized to 14CO2. Poor lactate absorption at physiologic pH and in the distal intestine might lead to an osmotic diarrhea in certain patients with malabsorption.