Mitochondrial oxygen consumption and ATP content in control and pyrene‐exposed frogs

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are a class of ubiquitous environmental contaminants. Exposure to pyrene, a PAH, elicits significant decreases in exercise performance, muscle contractile strength, and mitochondrial membrane potential and O2 consumption in R. pipiens. This study quantified mitochondrial O2 consumption and ATP content in R. pipiens and R. catesbeiana liver, muscle, and skin following a 7 day in‐water pyrene exposure. Mitochondria were isolated by differential centrifugation, and complex I (CI) and complex II (CII)‐initiated mitochondrial O2 consumption was measured using a Clark‐type O2 electrode. CI ‐ initiated O2 consumption was stimulated by addition of malate/glutamate while CII was stimulated by succinate. Mitochondrial ATP content was quantified via a luciferin‐luciferase chemiluminescent assay. CI and CII ‐ initiated mitochondrial O2 consumption significantly decreased 15‐50% in the three tissues following pyrene exposure. ATP content significantly decreased after pyrene exposure. Decreased ATP could disrupt numerous ATP‐dependent processes and offer an explanation for impaired muscle performance following pyrene exposure. Funding was provided by the National Tri‐Beta Research Scholarship Foundation, Bjorklund Endowed Research Fund, NSF‐REU, Biotechnology Research and Development Corporation, and Bradley University Research Excellence Grant.