title: The role of monocarboxylate transporters in uptake of lactic acid in HeLa cells.
abstract: This study was aimed to identify the monocarboxylate transporters (MCTs) in HeLa cells and to delineate their role in transportation of L-lactic acid. The functional role of MCTs in lactic acid transport was evaluated at various mucosal pHs (4.5-7.4) or in the presence of various loading doses (0.2-2mM) of lactic acid, MCT substrates (nicotinic acid, n-butyric acid, etc.) and inhibitors (alpha-cyano-4-hydroxycinnamate and para-chloromercuribenzoic acid). The molecular properties of MCTs were characterized using reverse transcription-polymerase chain reaction (RT-PCR). The uptake rate of lactic acid by HeLa cells significantly increased from 0.353+/-0.052 to 1.103+/-0.196 micromol/mg protein as the extra-cellular pH changed from 7.4 to 4.5, indicating that activities of MCT were mediated through H(+)-linked mechanism. The uptake profile of lactic acid followed the saturable process with the K(m) value of 0.53 mM. The uptake rate of lactic acid is concentration dependent and is reduced in the presence of MCT inhibitors. MCT isoforms 1, 5 and 6 in HeLa cells were identified by RT-PCR. HeLa cell line can be used as an effective screening tool for intravaginally administered drugs targeted toward MCT.
authors.affiliation: Division of Pharmaceutical Sciences, University of Missouri, School of Pharmacy, 5005 Rock Hill Road, Kansas City, MO 64110-2499, USA.
authors.forename: Sravanthi
authors.initials: S
authors.lastname: Cheeti
authors.forename: Bharat K
authors.initials: BK
authors.lastname: Warrier
authors.forename: Chi H
authors.initials: CH
authors.lastname: Lee
mesh_terms: D001692:Biological Transport / Q000187:drug effects; D020148:Butyric Acid / Q000494:pharmacology; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / Q000494:pharmacology; D002470:Cell Survival; D003373:Coumaric Acids / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D006367:HeLa Cells; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007476:Ionophores / Q000494:pharmacology; D019344:Lactic Acid / Q000378:metabolism / Q000493:pharmacokinetics*; D027501:Monocarboxylic Acid Transporters / Q000235:genetics / Q000502:physiology*; D009539:Nicotinic Acids / Q000494:pharmacology; D020033:Protein Isoforms / Q000235:genetics / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D020245:p-Chloromercuribenzoic Acid / Q000494:pharmacology
chemical_list: D003373:Coumaric Acids; D007476:Ionophores; D027501:Monocarboxylic Acid Transporters; D009539:Nicotinic Acids; D020033:Protein Isoforms; D020148:Butyric Acid; C007175:alpha-cyano-4-hydroxycinnamate; D019344:Lactic Acid; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; D020245:p-Chloromercuribenzoic Acid