Hepatic taurine transport: a Na/sup +/-dependent carrier on the basolateral plasma membrane

Journal Article · Tue Sep 01 00:00:00 EDT 1987 · Am. J. Physiol.; (United States)

OSTI ID:7039932

Bucuvalas, J C; Goodrich, A L; Suchy, F J

Highly purified rat basolateral liver plasma membrane vesicles were used examine the mechanism and the driving forces for hepatic uptake of the ..beta..-amino acid, taurine. An inwardly directed 100 mM NaCl gradient stimulated the initial rate of taurine uptake and energized a transient twofold accumulation of taurine above equilibrium (overshoot). In contrast, uptake was slower and no overshoot was detected in the presence of a KCl gradient. A negative intravesicular electrical potential generated by the presence of permeant anions or an outwardly directed K/sup +/ gradient with valinomycin increased Na/sup +/-stimulated taurine uptake. External Cl/sup -/ stimulated Na/sup +/-dependent taurine uptake independent of effects on the transmembrane electrical potential difference. Na/sup +/-dependent taurine uptake showed a sigmoidal dependence on extravesicular Na/sup +/ concentration, suggesting multiple Na/sup +/ ions are involved in the translocation of each taurine molecule. Na/sup +/-dependent taurine uptake demonstrated Michaelis-Menten kinetics with a maximum velocity of 0.537 nmol x mg protein/sup -1/ x min/sup -1/ and an apparent K/sub m/ of 174 ..mu..M. (/sup 3/H)taurine uptake was inhibited by the presence of excess unlabeled taurine, ..beta..-alanine, or hypotaurine but not by L-glutamine or L-alanine. In summary, using basolateral liver plasma membrane vesicles, the authors have shown that hepatic uptake of taurine occurs by a carrier-mediated, secondary active transport process specific for ..beta..-amino acids. Uptake is electrogenic, stimulated by external Cl/sup -/, and requires multiple Na/sup +/ ions for the translocation of each taurine molecule.

• Research Organization: Univ. of Cincinnati College of Medicine, OH (USA)
• OSTI ID: 7039932
• Journal Information: Am. J. Physiol.; (United States), Vol. 253:3
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
TAURINE
BIOCHEMICAL REACTION KINETICS
MEMBRANE TRANSPORT
TRITIUM COMPOUNDS
CATIONS
CELL MEMBRANES
DOSE-RESPONSE RELATIONSHIPS
LIVER
RATS
SODIUM CHLORIDES
TIME DEPENDENCE
ALKALI METAL COMPOUNDS
AMINES
ANIMALS
BODY
CELL CONSTITUENTS
CHARGED PARTICLES
CHLORIDES
CHLORINE COMPOUNDS
DIGESTIVE SYSTEM
GLANDS
HALIDES
HALOGEN COMPOUNDS
IONS
KINETICS
LABELLED COMPOUNDS
MAMMALS
MEMBRANES
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
ORGANS
REACTION KINETICS
RODENTS
SODIUM COMPOUNDS
SULFONIC ACIDS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques