Mitochondrial lactate dehydrogenase is involved in oxidative-energy metabolism in human astrocytoma cells (CCF-STTG1).
Lactate has long been regarded as an end product of anaerobic energy production and its fate in cerebral metabolism has not been precisely delineated. In this report, we demonstrate, for the first time, the ability of a human astrocytic cell line (CCF-STTG1) to consume lactate and to generate ATP via oxidative phosphorylation. (13)C-NMR and HPLC analyses aided in the identification of tricarboxylic acid (TCA) cyle metabolites and ATP in the astrocytic mitochondria incubated with lactate. Oxamate, an inhibitor of lactate dehydrogenase (LDH), abolished mitochondrial lactate consumption. Electrophoretic and fluorescence microscopic analyses helped localize LDH in the mitochondria. Taken together, this study implicates lactate as an important contributor to ATP metabolism in the brain, a finding that may significantly change our notion of how this important organ manipulates its energy budget.
Lemire
Joseph
J
Department of Chemistry and Biochemistry, Laurentian University, Sudbury, Ontario, Canada.
Mailloux
Ryan J
RJ
Appanna
Vasu D
VD
D000255:Adenosine Triphosphate / Q000378:metabolism; D001254:Astrocytoma / Q000378:metabolism*; D045744:Cell Line, Tumor; D019069:Cell Respiration; D004734:Energy Metabolism; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000032:analysis / Q000378:metabolism*; D019344:Lactic Acid / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000032:analysis / Q000378:metabolism*; D010085:Oxidative Phosphorylation
D024101:Mitochondrial Proteins; D019344:Lactic Acid; D000255:Adenosine Triphosphate; D007770:L-Lactate Dehydrogenase