title: Zinc and calcium modulate mitochondrial redox state and morphofunctional integrity.
abstract: Zinc and calcium have highly interwoven functions that are essential for cellular homeostasis. Here we first present a novel real-time flow cytometric technique to measure mitochondrial redox state and show it is modulated by zinc and calcium, individually and combined. We then assess the interactions of zinc and calcium on mitochondrial H2O2 production, membrane potential (ΔΨm), morphological status, oxidative phosphorylation (OXPHOS), complex I activity, and structural integrity. Whereas zinc at low doses and both cations at high doses individually and combined promoted H2O2 production, the two cations individually did not alter mitochondrial redox state. However, when combined at low and high doses the two cations synergistically suppressed and promoted, respectively, mitochondrial shift to a more oxidized state. Surprisingly, the antioxidants vitamin E and N-acetylcysteine showed pro-oxidant activity at low doses, whereas at high antioxidant doses NAC inhibited OXPHOS and dyscoupled mitochondria. Individually, zinc was more potent than calcium in inhibiting OXPHOS, whereas calcium more potently dissipated the ΔΨm and altered mitochondrial volume and ultrastructure. The two cations synergistically inhibited OXPHOS but antagonistically dissipated ΔΨm and altered mitochondrial volume and morphology. Overall, our study highlights the importance of zinc and calcium in mitochondrial redox regulation and functional integrity. Importantly, we uncovered previously unrecognized bidirectional interactions of zinc and calcium that reveal distinctive foci for modulating mitochondrial function in normal and disease states because they are potentially protective or damaging depending on conditions.
authors.affiliation: Department of Biomedical Sciences, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE C1A 4P3, Canada; Faculty of Veterinary Medicine, Cairo University, Giza 12211, Egypt.
authors.forename: Mahmoud S
authors.initials: MS
authors.lastname: Sharaf
authors.affiliation: Department of Biomedical Sciences, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE C1A 4P3, Canada; Canadian Rivers Institute, Department of Biology, University of Prince Edward Island, Charlottetown, PE C1A 4P3, Canada.
authors.forename: Michael R
authors.initials: MR
authors.lastname: van den Heuvel
authors.affiliation: Department of Biomedical Sciences, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE C1A 4P3, Canada.
authors.forename: Don
authors.initials: D
authors.lastname: Stevens
authors.affiliation: Department of Biomedical Sciences, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE C1A 4P3, Canada. Electronic address: ckamunde@upei.ca.
authors.forename: Collins
authors.initials: C
authors.lastname: Kamunde
mesh_terms: D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D053078:Membrane Potential, Mitochondrial; D008930:Mitochondria, Liver / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D053142:Mitochondrial Size; D017686:Oncorhynchus mykiss; D010084:Oxidation-Reduction; D010085:Oxidative Phosphorylation; D018384:Oxidative Stress; D017382:Reactive Oxygen Species; D015032:Zinc / Q000494:pharmacology*
chemical_list: D017382:Reactive Oxygen Species; D015032:Zinc; D002118:Calcium
keywords: Calcium; Free radicals; Mitochondria; Mitochondrial membrane potential; Mitochondrial volume homeostasis; Real-time flow cytometry; Redox regulation; Zinc