Transport of D-lactate in perfused rat liver.
The transport of D-lactate across the plasma membrane was investigated in hemoglobin-free perfused rat livers, applying the multiple-indicator dilution technique (pulse labelling of D-lactate and indicator substances). The following results were obtained: 1. The steady state exchange rate at 1 mM D-lactate was 2.5 mumol x min-1 x g wet wt-1. It was proportional to the extracellular concentration in the range between 0.1 and 70 mM. 2. The transport of D-lactate was inhibited by L-lactate and pyruvate; 50% inhibition was observed at 40 mM L-lactate or 5 mM pyruvate. 3. The transport was also inhibited by alpha-cyanocinnamate and 4,4'-diisocyanostilbene-2,2'-disulfonic acid. The inhibition by cyanocinnamate was complete (with 25 mM) and fully reversible, whereas the inhibition by diisothiocyanostilbenedisulfonic acid was incomplete and irreversible; it was dependent upon the amount of diisothiocyanostilbenedisulfonic acid bound by the liver. Maximal inhibition (80%) was observed with 2 mumol diisothiocyanostilbenedisulfonic acid bound per g wet weight. 4. The intracellular concentration (ci) of D-lactate was proportional to the extracellular concentration (ce); the ratio ci/ce was 0.5 throughout the concentration range studied. It decreased in the presence of L-lactate or pyruvate. It is concluded that the transport of D-lactate is carrier-mediated, and, at least partially, electroneutral.
D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport; D002462:Cell Membrane / Q000378:metabolism; D002934:Cinnamates / Q000494:pharmacology; D003201:Computers; D066298:In Vitro Techniques; D007536:Isomerism; D007700:Kinetics; D007773:Lactates / Q000378:metabolism* / Q000494:pharmacology; D008099:Liver / Q000378:metabolism*; D008297:Male; D009570:Nitriles / Q000494:pharmacology; D010477:Perfusion; D011773:Pyruvates / Q000494:pharmacology; D051381:Rats
D002934:Cinnamates; D007773:Lactates; D009570:Nitriles; D011773:Pyruvates; C018253:alpha-cyanocinnamate; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid