Estudos comparativos da bioenergética mitocondrial do Lophiosilurus alexandri

Abstract

Mitochondria are organelles responsible for the synthesis of ATP, and the complex of the respiratory chain and the enzyme ATP synthase those responsible for this process. Mitochondria are also one of the sources of generation of reactive oxygen species, yet has an efficient antioxidant system. Lophiosilurus alexandri (pacamã) is a native fish from the São Francisco river and has a great economic potential for the region. However, energy metabolism parameters from this fish has never been assessed. In this study, we sought to investigate the transport chain activity of electrons evaluating each of its complexes, as well as evaluated the mitochondrial H2O2 production and activity of antioxidant enzymes: superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) from liver pacamã and tilapia. In vitro experiments showed that phosphorylation velocity (V3), using a substrate for the complex I, was higher than complex II, this result was not found for the resting velocity (V4) and uncoupling velocity (VFCCP), which were higher when used for substrate complex II. Furthermore, the respiratory control (RC), which is a ration between V3 and V4, in pacamã shown a lower result than in tilapia, in both complexes 20% lower for substrate to complex I and 28% lower using substrate to complex II. It was also observed an average of 19% increase in mitochondrial H2O2 production from pacamã compared to tilapia. In relation to the antioxidant activity of liver enzymes, SOD had a reduced activity when comparing tilapia to pacamã, which showed a decrease of 27.2%. But in the case of CAT and GPx enzymes, such enzymes from tilapia shown to have greater activity than those from pacamã. The results indicate that, liver mitochondria from pacamã was the four functional complexes of the respiratory chain and H2O2 there is mitochondria H2O2 production, additionally pacamã liver SOD activity is reduced.