Carrier-mediated lactate entry into isolated hepatocytes from fed and starved rats: Zonal distribution and temperature dependence |
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Authors: | M A Staricoff R D Cohen J P Monson |
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Institution: | (1) Cellular Mechanisms Research Group, The London Hospital Medical College, University of London, UK;(2) University of Bristol, Department of Biochemistry, School of Medical Sciences, University Walk, BS8 1TD Bristol, UK |
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Abstract: | We examined the possibility of quantitative differences in lactate entry into periportal and perivenous hepatocytes under different nutritional states. The rate of14C-L(+)-lactate uptake was determined after 15-second incubations with freshly isolated zonally separated hepatocytes using a centrifuge stop technique at 37 °C and 4 °C, in the presence or absence of either differing amounts of unlabelled lactate or of a hepatocyte lactate transport inhibitor,-cyano-3-hydroxycinnamate. Total entry as well as carrier mediated entry of14C-L(+)-lactate into the isolated cell populations was found to be similar in periportal and perivenous hepatocytes, irrespective of the nutritional state of the animal. Periportal and perivenous hepatocytes showed 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 eightfold in transport studies conducted at 4 °C; similar results were obtained in unseparated and zonally separated suspensions. Temperature dependence of the hepatocyte transporter is markedly less than that reported for the erythrocyte transporter. |
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Keywords: | lactate transport hepatic heterogeneity temperature dependence |
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