Oxidative stress indicators and trace element concentrations in tissues of mako shark (Isurus oxyrinchus)

Liver, kidney and muscle from juvenile mako sharks (Isurus oxyrinchus) were collected in Baja California Sur. Lead (Pb), cadmium (Cd), mercury (Hg) and arsenic (As) concentrations were determined by atomic absorption spectrophotometry. The production of superoxide radical (O₂^•-) was measured as an indicator of reactive oxygen species production; lipid peroxidation (TBARS) and protein carbonyl levels were quantified as indicators of oxidative damage, and the activity of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR) and glutathione-S-transferase (GST) was assessed as indicator of antioxidant defenses. Two discriminant functions separated muscle from liver and kidney samples. Cd concentration was lower in muscle than in kidney (p<0.05) and Hg concentration was higher in muscle than in liver and kidney (p<0.05). Although GR and SOD activities were higher, oxidative damage (TBARS and carbonyl protein levels) was also higher in kidney (p<0.05). SOD activity, TBARS levels, and Cd and Hg concentration were the set of predictors with significant relevance during tissue discrimination. Tissue metabolism, physiology of the organisms and environmental factors may be related to the differences in trace elements and oxidative stress indicators found in muscle, liver and kidney of the mako shark.