Expression of Classical Mitochondrial Respiratory Responses in Homogenates of Rat Forebrain

Neil R. Sims, John P. Blass

Research output: Contribution to journalArticlepeer-review

59 Citations (Scopus)

Abstract

Abstract: Respiratory studies of brain mitochondria have, in general, been limited to purified preparations. Conventional procedures for mitochondrial isolation yield relatively small and potentially selected sub fractions of mitochondria. Examination of respiratory responses of homogenates of rat forebrain indicated that key respiratory properties of mitochondria are fully expressed in these preparations. In a high K+ buffer, comparable to those commonly used for purified mitochondria, forebrain homogenates exhibited many of the characteristics of oxygen uptake by “free” mitochondria: requirement for both pyruvate and malate for maximal respiration, stimulation (over threefold) by ADP, stimulation by uncoupling agent [carbonyl cyanide m‐chlorophenylhydrazone (CCCP)], but little effect of digitonin. In a modified Krebs‐Ringer phosphate buffer (a physiological buffer), respiratory responses were primarily due to mitochondria enclosed in synaptosomes: respiration with glucose was markedly stimulated by CCCP, further stimulated by pyruvate, and extensively inhibited by digitonin (which disrupts the cholesterol‐rich synaptosomal membranes). Studies with purified mitochondria and synaptosomes supported the specificity of these responses. These data indicate that classical mitochondrial responses are expressed in whole brain homogenates and, under appropriate conditions, provide functional measures of the total pools of free and synaptosomal mitochondria.

Original languageEnglish
Pages (from-to)496-505
Number of pages10
JournalJournal of Neurochemistry
Volume47
Issue number2
DOIs
Publication statusPublished - Aug 1986
Externally publishedYes

Keywords

  • MitochondriA
  • Oxygen uptake
  • Synaptosomes

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