Mixed function oxidation of hexobarbital and generation of NADPH by the hexose monophosphate shunt in isolated rat liver cells. |
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Authors: | O Junge K Brand |
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Institution: | Max-Planck-Institut für Ernährungsphysiologie, Dortmund, Federal Republic of Germany |
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Abstract: | Mixed function oxidation of hexobarbital and the generation of NADPH by the hexose monophosphate shunt were studied in isolated rat liver parenchymal cells from phenobarbital-pretreated and untreated animals. In cells isolated from untreated rats, a maximal rate of hexobarbital oxidation of 17 μmol·g?1 liver wet weight·(60 min)?1 was observed, while in cells isolated from phenobarbital-pretreated rats a maximal rate of 29 μmol·g?1 liver wet weight·(60 min)?1 has been obtained. On the basis of the specific radioactivity at carbon atom 1 of glucose 6-phosphate, fructose 6-phosphate and 6-phosphogluconate, determined by enzymatic decarboxylation, a ratio between NADPH formation via the hexose monophosphate shunt and NADH utilization for hexobarbital oxidation of 6:1 in untreated and 9.5:1 in pretreated cells has been obtained. With phenazine methosulfate the stimulation of NADPH generation via the hexose monophosphate shunt exceeded that observed in the presence of hexobarbital by 329 and 160%, respectively, indicating that the capacity of this pathway is sufficient to provide more reducing equivalents than are required for maximal rates of mixed function oxidation. |
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Keywords: | Present address: Institut für Physiologische Chemie Lehrstuhl II D-8520 Erlangen Egerlandstrasse 7 FRG to whom requests for reprints should be sent |
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