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

Masako Inuyama, Fumihiko Ushigome, Akiko Emoto, Noriko Koyabu, Shoji Satoh, Kiyomi Tsukimori, Hitoo Nakano, Hisakazu Ohtani, Yasufumi Sawada

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Abstract

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-[14C]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-[14C]lactic acid uptake exhibited saturation kinetics with a Km value of 5.89 ± 0.68 mM in the presence of a pH gradient. p-Chloromercuribenzenesulfonate and α-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.

Original languageEnglish
Pages (from-to)C822-C830
JournalAmerican Journal of Physiology - Cell Physiology
Volume283
Issue number3 52-3
Publication statusPublished - 2002 Sep 1
Externally publishedYes

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Keywords

  • Human placenta
  • Monocarboxylic acid
  • Trophoblast

ASJC Scopus subject areas

  • Physiology
  • Cell Biology

Cite this

Inuyama, M., Ushigome, F., Emoto, A., Koyabu, N., Satoh, S., Tsukimori, K., Nakano, H., Ohtani, H., & Sawada, Y. (2002). Characteristics of L-lactic acid transport in basal membrane vesicles of human placental syncytiotrophoblast. American Journal of Physiology - Cell Physiology, 283(3 52-3), C822-C830.