Effects of sevoflurane and its metabolite hexafluoroisopropanol on hypoxia/reoxygenation-induced injury and mitochondrial bioenergetics in murine cardiomyocytes

Birgit Roth Z'graggen; Martin Urner; Beatrice Beck-Schimmer; Martin Schläpfer

doi:10.1016/j.bjao.2022.100116

Effects of sevoflurane and its metabolite hexafluoroisopropanol on hypoxia/reoxygenation-induced injury and mitochondrial bioenergetics in murine cardiomyocytes

BJA Open. 2022 Dec 30:5:100116. doi: 10.1016/j.bjao.2022.100116. eCollection 2023 Mar.

Authors

Birgit Roth Z'graggen¹, Martin Urner^{1

2

3}, Beatrice Beck-Schimmer^{1

4}, Martin Schläpfer^{1

4}

Affiliations

¹ Institute of Physiology, University of Zurich, Zurich, Switzerland.
² Interdepartmental Division of Critical Care Medicine and University of Toronto, Toronto, Canada.
³ Institute of Health Policy, Management, and Evaluation, University of Toronto, Toronto, Canada.
⁴ Institute of Anaesthesiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland.

Abstract

Background: The volatile anaesthetic sevoflurane protects cardiac tissue from reoxygenation/reperfusion. Mitochondria play an essential role in conditioning. We aimed to investigate how sevoflurane and its primary metabolite hexafluoroisopropanol (HFIP) affect necrosis, apoptosis, and reactive oxygen species formation in cardiomyocytes upon hypoxia/reoxygenation injury. Moreover, we aimed to describe the similarities in the mode of action in a mitochondrial bioenergetics analysis.

Methods: Murine cardiomyocytes were exposed to hypoxia (0.2% O₂ for 6 h), followed by reoxygenation (air with 5% CO₂ for 2 h) in the presence or absence sevoflurane 2.2% or HFIP 4 mM. Lactate dehydrogenase (LDH) release (necrosis), caspase activation (apoptosis), reactive oxygen species, mitochondrial membrane potential, and mitochondrial function (Seahorse XF analyser) were measured.

Results: Hypoxia/reoxygenation increased cell death by 44% (+31 to +55%, P<0.001). Reoxygenation in the presence of sevoflurane 2.2% or HFIP 4 mM increased LDH release only by +18% (+6 to +30%) and 20% (+7 to +32%), respectively. Apoptosis and reactive oxygen species formation were attenuated by sevoflurane and HFIP. Mitochondrial bioenergetics analysis of the two substances was profoundly different. Sevoflurane did not influence oxygen consumption rate (OCR) or extracellular acidification rate (ECAR), whereas HFIP reduced OCR and increased ECAR, an effect similar to oligomycin, an adenosine triphosphate (ATP) synthase inhibitor. When blocking the metabolism of sevoflurane into HFIP, protective effects of sevoflurane - but not of HFIP - on LDH release and caspase were mitigated.

Conclusion: Together, our data suggest that sevoflurane metabolism into HFIP plays an essential role in cardiomyocyte postconditioning after hypoxia/reoxygenation injury.

Keywords: hexafluoroisopropanol; hypoxia/reoxygenation injury; mitochondrial bioenergy measurements; mitochondrial membrane potential depolarisation; oxygen consumption rate; postconditioning; sevoflurane; volatile anaesthetic protection.