Thiamine transport by basolateral rat liver plasma membrane vesicles

Gastroenterology. 1992 Sep;103(3):1056-65. doi: 10.1016/0016-5085(92)90043-x.


Hepatic thiamine transport is thought to be a saturable, Na(+)- and energy-dependent process. However, the transport of this organic cation has not been examined in experimental models that allow direct characterization of carrier-mediated processes. Recently, a sinusoidal organic cation/H+ antiport was identified, using N1-methylnicotinamide as a marker. To determine whether thiamine is a substrate for this antiport, the characteristics of thiamine uptake were examined in rat liver basolateral membrane vesicles. An inwardly directed Na+ gradient had no effect on thiamine uptake as compared with an identical K+ gradient. An outwardly directed H+ gradient stimulated thiamine uptake as compared with pH-equilibrated conditions, and H(+)-dependent uptake was not the result of an H+ diffusion potential. Identical pH gradients stimulated uptake under voltage-clamped conditions, consistent with electroneutral thiamine/H+ exchange. Unlabeled intravesicular thiamine trans-stimulated [3H]thiamine uptake. Choline and imipramine cis-inhibited thiamine/H+ exchange; a series of other organic cations and thiamine analogues had no effect. Carrier-mediated [3H]thiamine uptake showed two saturable systems. In conclusion, a thiamine/H+ antiport is present on the sinusoidal membrane, distinct from Na+/H+ and NMN+/H+ exchange.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Biological Transport / drug effects
  • Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / pharmacology
  • Cell Membrane / metabolism
  • Hydrogen / metabolism*
  • Hydrogen-Ion Concentration
  • Liver / metabolism*
  • Liver / ultrastructure
  • Osmolar Concentration
  • Potassium / metabolism
  • Rats
  • Sodium / metabolism
  • Thiamine / pharmacokinetics*
  • Valinomycin / pharmacology


  • Valinomycin
  • Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone
  • Hydrogen
  • Sodium
  • Potassium
  • Thiamine