• Amanda R Scharenbrock, Luke A Borchardt, Zachariah P G Olufs, David A Wassarman, and Misha Perouansky.
• Department of Anesthesiology, SMPH, University of Wisconsin-Madison, Madison, Wisconsin, USA.
• Paediatr Anaesth. 2024 Dec 1; 34 (12): 124012491240-1249.

BackgroundIndividuals with mitochondrial defects, especially those in Complex I of the electron transport chain, exhibit behavioral hypersensitivity and toxicity to volatile anesthetics. In Drosophila melanogaster, mutation of ND23 (NDUFS8 in mammals), which encodes a subunit of the matrix arm of Complex I, sensitizes flies to toxicity from isoflurane but not an equipotent dose of sevoflurane. Also, in ND23 flies, both anesthetics activate expression of stress response genes, but to different extents. Here, we investigated the generality of these findings by examining flies mutant for ND2 (ND2 in mammals), which encodes a subunit of the membrane arm of Complex I.MethodsThe serial anesthesia array was used to expose ND2del1 and ND2360114 flies to precise doses of isoflurane, sevoflurane, and oxygen. Behavioral sensitivity was assessed by a climbing assay and toxicity by percent mortality within 24 h of exposure. Changes in expression were determined by qRT-PCR of RNA isolated from heads at 0.5 h after anesthetic exposure.ResultsUnlike ND2360114, ND2del1 did not affect behavioral sensitivity to isoflurane or sevoflurane. Furthermore, sevoflurane in hyperoxia as well as anoxia caused mortality of ND2del1 but not ND2360114 flies. Finally, the mutations had different effects on induction of stress response gene expression by the anesthetics.ConclusionMutations in different arms of Complex I resulted in different behavioral sensitivities and toxicities to isoflurane and sevoflurane, indicating that (i) the anesthetics have mechanisms of action that involve arms of Complex I to different extents and (ii) the lack of behavioral hypersensitivity does not preclude susceptibility to anesthetic toxicity.© 2024 The Author(s). Pediatric Anesthesia published by John Wiley & Sons Ltd.

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