Ma. Staricoff et al., CARRIER-MEDIATED LACTATE ENTRY INTO ISOLATED HEPATOCYTES FROM FED ANDSTARVED RATS - ZONAL DISTRIBUTION AND TEMPERATURE-DEPENDENCE, Bioscience reports, 15(2), 1995, pp. 99-109
We examined the possibility of quantitative differences in lactate ent
ry into periportal and perivenous hepatocytes under different nutritio
nal states. The rate of C-14-L(+)-lactate uptake was determined after
15-second incubations with freshly isolated zonally separated hepatocy
tes using a centrifuge stop technique at 37 degrees C and 4 degrees C,
in the presence or absence of either differing amounts of unlabelled
lactate or of a hepatocyte lactate transport inhibitor, alpha-cyano-3-
hydroxycinnamate. Total entry as well as carrier mediated entry of C-1
4-L(+)-lactate into the isolated cell populations was found to be simi
lar in periportal and perivenous hepatocytes, irrespective of the nutr
itional state of the animal. Periportal and perivenous hepatocytes sho
wed a greater tendency to transport lactate when isolated from starved
animals, in agreement with previously reported data from non-zonally
separated isolated hepatocytes. The activity of the hepatocyte plasma-
membrane lactate transporter was diminished between fourfold and eight
fold in transport studies conducted at 4 degrees C; similar results we
re obtained in unseparated and zonally separated suspensions. Temperat
ure dependence of the hepatocyte transporter is markedly less than tha
t reported for the erythrocyte transporter.