PODEROSO Juan Jose
capítulos de libros
Nitric oxide decreases oxidative metabolism in the rat diaphragm during endotoxemia by the formation of oxygen active species an peroxynitrite in mitochondria
LISDERO, CL, LANONE, S, CARRERAS, MC, AUBIER, M, PODEROSO, JJ, BOCZKOWSKI, J
The Biology of Nitric Oxide, Part 6
Año: 1998; p. 135 - 138
Diaphragmatic failure accounts for an increase in morbility and mortality of critically ill septic patients. The causes of muscular insufficiency are not clearly defined though oxidative stress, cytokine effects and, recently, nitric oxide overproduction have been reported. In this study, we analyzed rat diaphragm iNOS expression and activity, mitochondrial respiration and production of hydrogen peroxide (H2O2) related to diaphragm function in an endotoxemia model. Three Sprague-Dawley rat groups were I.P. injected with saline solution (group A), 10 mg/kg E.coli endotoxin (group B) and the same dose of endotoxin plus 1 mg/kg L-NMMA I.V(group C). The diaphragms were excised 6 hs later and muscle contractility (force-transducer), iNOS expression (western-blot) and activity (citrulline method) were determined; in addition, diaphragm mitochondria were isolated by differential centrifugation and O2 uptake (with and without ADP acceptor) and release of H2O2 (by fluorometry) were assayed. The results showed that, in group B, a fall in diaphragm force-frequency was associated with a 3 fold increase in NO production and iNOS expression, a 40% decrease in mitochondrial respiratory control and an 80% increase in released H2O2, compared to group A. In group C, the parameters approached to group A. Moreover, nitrotyrosine residues were found by HPLC only in group B mitochondria. These results suggest that in endotoxemia, NO overproduction induces a concomitant production of oxygen active species and the formation of peroxynitrite with a decrease in mitochondrial respiration and muscle contractility. These effects are partially prevented by previous administration of L-NMMA.