Carnitine Absorption: Effects of Sodium Valproate and Sodium Octanoate in the Caco-2 Cell Culture Model of Human Intestinal Epithelium

• Published in: The Journal of nutritional biochemistry Vol. 9; no. 4; pp. 228 - 235
• Main Author: Rebouche, Charles J
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01.04.1998; Elsevier Science
• Subjects: ABSORCION DE SUSTANCIAS NUTRITIVAS; ABSORCION DIGESTIVA; absorption; ABSORPTION DE SUBSTANCES NUTRITIVES; ABSORPTION DIGESTIVE; ACIDE CAPRYLIQUE; ACIDO CAPRILICO; ALANINA; ALANINE; ANALOGS; APICAL MEDIUM; BASAL MEDIUM; Biological and medical sciences; BLOOD CIRCULATION; Caco-2 cells; CAPRYLIC ACID; CARNITINA; CARNITINE; CATION; CATIONES; CATIONS; cell culture; CIRCULACION SANGUINEA; CIRCULATION SANGUINE; DEBIT; DIGESTIVE ABSORPTION; FLOW RATE; Fundamental and applied biological sciences. Psychology; GASTO; GRADIENTS; HIDROGENO; HYDROGEN; HYDROGENE; INHIBICION; INHIBITION; INTESTIN; INTESTINAL ABSORPTION; Intestine. Mesentery; INTESTINES; INTESTINOS; KINETICS; MEDICAMENT NEUROTROPE; MEDICAMENTOS NEUROTROPICOS; MEMBRANA MUCOSA; MUCOUS MEMBRANE; MUQUEUSE; NEUROTROPIC DRUGS; NUTRIENT UPTAKE; NUTRIENTES; NUTRIENTS; OCTANOIC ACID; SODIO; SODIUM; STRUCTURE ACTIVITY RELATIONSHIPS; SUBSTANCE NUTRITIVE; TEMPS; TIEMPO; TIME; TRANSMONOLAYER FLUX; VALPROIC ACID; Vertebrates: digestive system; carnitine; Caco-2 cells; valproic acid; absorption; cell culture; Human; Cell line; Absorption; Nutrition; Digestive system; Biological transport; Colon; Valproic acid; In vitro; Octanoic acid; Mechanism; Carnitine
• ISSN: 0955-2863; 1873-4847
• DOI: 10.1016/S0955-2863(98)00004-7

The Caco-2 cell culture system was used as a model to investigate the mechanism of carnitine absorption in human small intestinal epithelium, and to determine if valproic acid inhibits this process in the model system. The hypotheses tested were: Carnitine is absorbed by a mechanism not involving carrier-mediated transport; and valproic acid specifically inhibits carnitine absorption. Results of the investigation were consistent with exclusively passive, paracellular absorption of carnitine across the Caco-2 cell monolayer. Saturable and structure-specific intracellular accumulation of carnitine from the apical medium was observed, but was independent of the process of absorption. At high concentration (10 mmol/L), both sodium valproate and its straight-chain analog sodium octanoate inhibited cellular accumulation of carnitine from the apical medium, but enhanced transmonolayer passage of carnitine from the apical to the basal medium. Lower concentrations of these organic acid salts (0.1 or 1 mmol/L) did not affect cellular accumulation of carnitine, but at 1 mmol/L concentration, they slightly enhanced transmonolayer flux. Paradoxically, cells cultured for 5 days in the presence of sodium valproate or sodium octanoate accumulated carnitine at a faster rate than cells cultured in the absence of these compounds. It is concluded that carnitine is absorbed across the Caco-2 monolayer by a passive, paracellular route that is not inhibited by sodium valproate.