Characteristics of L-lactic acid transport in basal membrane vesicles of human placental syncytiotrophoblast

• Published in: American Journal of Physiology: Cell Physiology Vol. 283; no. 3; pp. C822 - C830
• Main Authors: Inuyama, Masako, Ushigome, Fumihiko, Emoto, Akiko, Koyabu, Noriko, Satoh, Shoji, Tsukimori, Kiyomi, Nakano, Hitoo, Ohtani, Hisakazu, Sawada, Yasufumi
• Format: Journal Article
• Language: English
• Published: United States 01.09.2002
• Subjects: 4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid - pharmacology; 4-Chloromercuribenzenesulfonate - pharmacology; Biological Transport, Active - drug effects; Biological Transport, Active - physiology; Carbon Radioisotopes; Carboxylic Acids - pharmacology; Cell Membrane - chemistry; Cell Membrane - metabolism; Cell Separation; Coumaric Acids - pharmacology; Enzyme Inhibitors - pharmacology; Female; Humans; Hydrogen-Ion Concentration; Kinetics; Lactic Acid - metabolism; Lactic Acid - pharmacokinetics; Microvilli - chemistry; Microvilli - metabolism; Monocarboxylic Acid Transporters - metabolism; Phloretin - pharmacology; Placenta - cytology; Sodium - metabolism; Subcellular Fractions - chemistry; Subcellular Fractions - metabolism; Trophoblasts - chemistry; Trophoblasts - cytology
• ISSN: 0363-6143; 1522-1563
• DOI: 10.1152/ajpcell.00545.2001

1  Department of Medico-Pharmaceutical Sciences, Graduate School of Pharmaceutical Sciences, and 2  Department of Reproduction and Gynecology, Graduate School of Medical Sciences, Kyushu University, Higashi-ku, Fukuoka 812-8582, Japan The characteristics of L -lactic acid transport across the trophoblast basal membrane were investigated and compared with those across the brush-border membrane by using membrane vesicles isolated from human placenta. The uptake of L -[ 14 C]lactic acid into basal membrane vesicles was Na + independent, and an uphill transport was observed in the presence of a pH gradient ([H + ] out  > [H + ] in ). L -[ 14 C]lactic acid uptake exhibited saturation kinetics with a K m value of 5.89 ± 0.68 mM in the presence of a pH gradient. p -Chloromercuribenzenesulfonate and -cyano-4-hydroxycinnamate inhibited the initial uptake, whereas phloretin or 4,4'-diisothiocyanostilbene-2,2'-disulfonate did not. Mono- and dicarboxylic acids suppressed the initial uptake. In conclusion, L -lactic acid transport in the basal membrane is H + dependent and Na + independent, as is also the case for the brush-border membrane transport, and its characteristics resemble those of monocarboxylic acid transporters. However, there were several differences in the effects of inhibitors between basal and brush-border membrane vesicles, suggesting that the transporter(s) involved in L -lactic acid transport in the basal membrane of placental trophoblast may differ from those in the brush-border membrane. human placenta; trophoblast; monocarboxylic acid