Complex I and ATP synthase mediate membrane depolarization and matrix acidification by isoflurane in mitochondria.

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Citation

Pravdic D, Hirata N, Barber L, Sedlic F, Bosnjak ZJ, Bienengraeber M

Complex I and ATP synthase mediate membrane depolarization and matrix acidification by isoflurane in mitochondria.

Eur J Pharmacol. 2012 Sep 5;690(1-3):149-57. doi: 10.1016/j.ejphar.2012.07.003. Epub 2012 Jul 11.

PubMed ID
22796646 [ View in PubMed
]
Abstract

Short application of the volatile anesthetic isoflurane at reperfusion after ischemia exerts strong protection of the heart against injury. Mild depolarization and acidification of the mitochondrial matrix are involved in the protective mechanisms of isoflurane, but the molecular basis for these changes is not clear. In this study, mitochondrial respiration, membrane potential, matrix pH, matrix swelling, ATP synthesis and -hydrolysis, and H(2)O(2) release were assessed in isolated mitochondria. We hypothesized that isoflurane induces mitochondrial depolarization and matrix acidification through direct action on both complex I and ATP synthase. With complex I-linked substrates, isoflurane (0.5mM) inhibited mitochondrial respiration by 28 +/- 10%, and slightly, but significantly depolarized membrane potential and decreased matrix pH. With complex II- and complex IV-linked substrates, respiration was not changed, but isoflurane still decreased matrix pH and depolarized mitochondrial membrane potential. Depolarization and matrix acidification were attenuated by inhibition of ATP synthase with oligomycin, but not by inhibition of mitochondrial ATP- and Ca(2+)-sensitive K(+) channels or uncoupling proteins. Isoflurane did not induce matrix swelling and did not affect ATP synthesis and hydrolysis, but decreased H(2)O(2) release in the presence of succinate in an oligomycin- and matrix pH-sensitive manner. Isoflurane modulated H(+) flux through ATP synthase in an oligomycin-sensitive manner. Our results indicate that isoflurane-induced mitochondrial depolarization and acidification occur due to inhibition of the electron transport chain at the site of complex I and increased proton flux through ATP synthase. K(+) channels and uncoupling proteins appear not to be involved in the direct effects of isoflurane on mitochondria.

DrugBank Data that Cites this Article

Drug Targets
DrugTargetKindOrganismPharmacological ActionActions
IsofluraneATP synthase subunit delta, mitochondrialProteinHumans
Unknown
Unknown
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