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Effect of fluorocitrate on cerebral oxidation of lactate and glucose in freely moving rats
Author(s) -
Ronald Zielke H.,
Zielke Carol L.,
Baab Peter J.,
Tyson Tildon J.
Publication year - 2007
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.2006.04335.x
Subject(s) - microdialysis , lactic acid , chemistry , metabolism , carbohydrate metabolism , in vivo , glucose uptake , interstitial fluid , catabolism , biochemistry , medicine , endocrinology , biology , extracellular , insulin , microbiology and biotechnology , bacteria , genetics
Glucose is the primary carbon source to enter the adult brain for catabolic and anabolic reactions. Some studies suggest that astrocytes may metabolize glucose to lactate; the latter serving as a preferential substrate for neurons, especially during neuronal activation. The current study utilizes the aconitase inhibitor fluorocitrate to differentially inhibit oxidative metabolism in glial cells in vivo . Oxidative metabolism of 14 C‐lactate and 14 C‐glucose was monitored in vivo using microdialysis and quantitating 14 CO 2 in the microdialysis eluate following pulse labeling of the interstitial glucose or lactate pool. After establishing a baseline oxidation rate, fluorocitrate was added to the perfusate. Neither lactate nor glucose oxidation was affected by 5 μ mol/L fluorocitrate. However, 20 and 100 μ mol/L fluorocitrate reduced lactate oxidation by 55 ± 20% and 68 ± 12%, respectively ( p < 0.05 for both). Twenty and 100 μ mol/L fluorocitrate reduced 14 C‐glucose oxidation by 50 ± 14% ( p < 0.05) and 24 ± 19% (ns), respectively. Addition of non‐radioactive lactate to 14 C‐glucose plus fluorocitrate decreased 14 C‐glucose oxidation by an additional 29% and 38%, respectively. These results indicate that astrocytes oxidize about 50% of the interstitial lactate and about 35% of the glucose. By subtraction, neurons metabolize a maximum of 50% of the interstitial lactate and 65% of the interstitial glucose.