Rundle 2018 Environ Sci Technol

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Rundle K, Sharaf M, Stevens D, Kamunde C, Van Den Heuvel MR (2018) Oil sands-derived naphthenic acids are oxidative uncouplers and impair electron transport in isolated mitochondria. Environ Sci Technol 52:10803-11.

» PMID: 30102860

Rundle K, Sharaf M, Stevens D, Kamunde C, Van Den Heuvel MR (2018) Environ Sci Technol

Abstract: Naphthenic acids (NAs) are predominant compounds in oil sands-influenced waters. These acids cause numerous acute and chronic effects in fishes. However, the mechanism of toxicity underlying these effects has not been fully elucidated. Due to their carboxylic acid moiety and the reported disruption of cellular bioenergetics by similar structures, we hypothesized that NAs would uncouple mitochondrial respiration with the resultant production of reactive oxygen species (ROS). Naphthenic acids were extracted and purified from 17-year-old oil sands tailings waters yielding an extract of 99% carboxylic acids with 90% fitting the classical O2-NA definition. Mitochondria were isolated from rainbow trout liver and exposed to different concentrations of NAs. Mitochondrial respiration, membrane potential, and ROS emission were measured using the Oroboros fluorespirometry system. Additionally, mitochondrial ROS emission and membrane potential were evaluated with real-time flow cytometry. Results showed NAs uncoupled oxidative phosphorylation, inhibited respiration, and increased ROS emission. The effective concentration (EC50) and inhibition concentration (IC50) values for the endpoints measured ranged from 21.0 to 157.8 mg/L, concentrations similar to tailings waters. For the same endpoints, EC10/IC10 values ranged from 11.8 to 66.7 mg/L, approaching concentrations found in the environment. These data unveil mechanisms underlying effects of NAs that may contribute to adverse effects on organisms in the

Keywords: Oil sands, Naphthenic acid, Mitochondria, ROS, Membrane potential Bioblast editor: Plangger M, Kandolf G O2k-Network Lab: CA Charlottetown Kamunde C

Labels: MiParea: Respiration, Pharmacology;toxicology 

Organism: Fishes  Tissue;cell: Liver  Preparation: Isolated mitochondria 

Regulation: Uncoupler  Coupling state: LEAK, OXPHOS, ET  Pathway: N, ROX  HRR: Oxygraph-2k 

Lables, 2018-08