Hyposmotically-activated efflux of L-carnitine from a human mammary cancer cell line.
Cell-swelling, induced by a hyposmotic challenge, stimulated the efflux of L-carnitine from a human mammary cancer cell line, MDA-MB-231. The response was dependent upon the extent of the osmotic shock. Hyposmotically-activated L-carnitine efflux was inhibited by the anion transport blocker diiodosalicylate. The efflux of taurine from MDA-MB-231 cells was also stimulated by a hyposmotic shock via a pathway sensitive to diiodosalicylate. L-carnitine efflux from MDA-MB-231 cells was stimulated by isosmotic swelling in a manner which was inhibited by diiodosalicylate. The results suggest that L-carnitine may exit cells via a volume-sensitive pathway: it is possible that L-carnitine efflux may utilize the same pathway as amino acids. The efflux of L-carnitine via this route could have a major effect on the intracellular concentration of L-carnitine and could facilitate transepithelial L-carnitine transport.
Shennan
D B
DB
Hannah Research Institute, Ayr. shennand@hri.sari.ac.uk
D001692:Biological Transport; D001943:Breast Neoplasms / Q000378:metabolism*; D002331:Carnitine / Q000378:metabolism*; D005260:Female; D006801:Humans; D009994:Osmolar Concentration; D012459:Salicylates / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D013654:Taurine / Q000378:metabolism; D014407:Tumor Cells, Cultured
D012459:Salicylates; D013654:Taurine; D012964:Sodium; D002331:Carnitine