Cardiac bioenergetics and mitochondrial pathways in a rat model of low and severe endotoxemia.

VANASCO, VIRGINIA; EVELSON, PABLO; VICO, TAMARA; MARCHINI, TIMOTEO; ADÁN AREÁN, JUAN SANTIAGO; ALVAREZ, SILVIA

Congreso; III International Congress in Translational Medicine; 2016

Despite being the major source of energy in the cell, mitochondria participate in multiple cell signaling pathways. Besides, mitochondria dysfunction is suggested to play a central role in inflammatory pathologies like metabolic, cardiovascular and neurological diseases, and also in acute endotoxemia and sepsis. The aim of this study was to analyze cardiac bioenergetics and mitochondrial function in low and severe endotoxemia. Female Sprague-Dawley rats (50 days old) were separated in three experimental groups and i.p. injected with a single dose of LPS (0.5 or 8 mg/kg) or vehicle. After 6 h of treatment, mitochondria were isolated from left ventricle. O2 uptake in state 4 (rest respiration state) and state 3 (active state) was measured, and a 9 % decrease in state 3 was observed in LPS 8 mg/kg groups (Control: 64.1±21 ng-atO/min.mg protein). A 10% and 15% decrease in the respiratory control ratio was also observed for LPS 0.5 mg/kg and LPS 8 mg/kg treated animals compared to control group (Control: 5.4, p˂0.05). Complex I-III activity showed a 20% decrease at the highest dose of LPS (Control: 96.7±14 nmol/min.mg protein, p˂0.05). Complex II-III and IV activities showed no statistical differences. ATP production was observed decreased by 33% at LPS 8 mg/kg treatment (Control: 186.2±55 nmol ATP/min.mg protein, p˂0.05). The calculated P/O ratios were 2.8; 2.2 and 2 for control, LPS 0.5 and 8 mg/kg; respectively. Mitochondrial membrane potential was measured by flow cytometry using a cationic die and showed a 10% decrease in LPS 8 mg/kg dose (Control IFM: 214±25, p˂0.05). To evaluate NO role in this inflammatory processes, iNOS and eNOS expression were measured by Western Blot in left ventricle tissue, showing an increase in both enzyme expressions for LPS 8 mg/kg treatment. Nitrate and nitrite concentration in plasma was also measured and a 10-hold and a 20-hold increase were observed in LPS 0.5 mg/kg and LPS 8 mg/kg respectively (Control: 37.4±10 µM, p˂0.0001). These results suggest that mitochondrial dysfunction occurs in different levels of endotoxemia, setting the mitochondria as a potential therapeutic target to treat inflammatory diseases.