Uptake of L-carnitine by a human intestinal epithelial cell line, Caco-2.
| Autor: | McCloud E; Department of Pediatrics, University of California College of Medicine, Irvine, USA., Ma TY, Grant KE, Mathis RK, Said HM |
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| Jazyk: | angličtina |
| Zdroj: | Gastroenterology [Gastroenterology] 1996 Dec; Vol. 111 (6), pp. 1534-40. |
| DOI: | 10.1016/s0016-5085(96)70015-x |
| Abstrakt: | Background & Aims: The mechanism of intestinal uptake of L-carnitine is controversial. The aim of this study was to clarify the mechanism and regulation of L-carnitine uptake. Methods: Uptake of [3H]-L-carnitine was measured across the apical membrane of confluent monolayers of Caco-2 cells. Results: [3H]-L-carnitine uptake was linear and appreciable for up to 7 minutes with minimal metabolic alteration, was temperature- and Na(+)-(but not pH-) dependent, and included a saturable component with an apparent Michaelis constant of 45.5 +/- 6.5 mumol/L and a maximum velocity of 83.5 +/- 5.6 nmol.mg protein-1.5 min-1. Unlabeled L-carnitine and its structurally related analogues significantly (P < 0.01) inhibited [3H]-L-carnitine uptake, whereas unrelated compounds were ineffective. L-Carnitine uptake was also energy-dependent, being significantly (P < 0.01) inhibited by metabolic inhibitors. Our results also suggested that a calmodulin- but not a protein kinase C- or protein kinase A-mediated pathway plays a role in regulating L-carnitine uptake by Caco-2 cells. Conclusions: L-carnitine uptake by intestinal epithelial cells (Caco-2) involves a carrier-mediated system that is temperature-, Na(+)-, and energy-dependent and seems to be under the regulation of a calmodulin-mediated pathway. |
| Databáze: | MEDLINE |
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