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Energy Metabolism in Rat Brain Synaptosomes from Nembutal‐Anesthetized and Nonanesthetized Animals
Author(s) -
Rafalowska Urszula,
Erecińska Maria,
Wilson David F.
Publication year - 1980
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.1471-4159.1980.tb11218.x
Subject(s) - synaptosome , creatine , oxidative phosphorylation , chemistry , mitochondrion , metabolism , cytochrome , halothane , biochemistry , respiration , medicine , biology , pharmacology , endocrinology , anatomy , membrane , enzyme , organic chemistry
Cellular energetic parameters including the intramitochondrial and cytosolic [NAD + ]/[NADH] ratios, the cellular [ATP]/[ADP][P i and [creatine phosphate]/[creatine] ratios, the concentration of cytochrome c and its redox state and the respiratory rate were studied in suspensions of rat brain synapto‐somes isolated from nembutal‐anesthetized and nonanesthetized animals. The ratio of [3‐hydroxybutyrate] to [acetoacetate] was 2.0 in synaptosomes isolated from nonanesthetized rats and 5.55 in those from anesthetized animals. The [lactate]/[pyruvate] ratio was 3.8 in the former and 10.9 in the latter preparation. The [ATP]/[ADP][P i ] was 3838 M −1 in the synaptosomes from anesthetized rats and 840 M −1 in those from nonanesthetized animals and the [creatine phosphate]/[creatine] ratios were 0.79 and 0.39, respectively. Cytochrome c was about 15% reduced in both preparations; however, the mitochon‐drial cytochrome concentration was almost twofold higher in the synaptosomes from nonanesthetized animals. Calculations of the free energy relationships between the mitochondrial redox reactions and ATP synthesis showed that in synaptosomes isolated from the brains of nembutal‐anesthetized rats the first two sites of oxidative phosphorylation were at near‐equilibrium, in agreement with observations for intact cells and tissues. The energetic parameters for synaptosomes from anesthetized rats are very similar to the values for intact whole brain, whereas those for synaptosomes from nonanesthetized rats are lower and suggest that nembutal anesthesia protects against some irreversible damage to the synaptosome during isolation. It is concluded that synaptosomes isolated from brains of nembutal‐anesthetized rats can be used as a convenient model system for studies of neuronal metabolism.