Abnormal mitochondrial fusion-fission balance contributes to the progression of experimental sepsis.

Sepsis-associated multiple organ failure is a major cause of mortality characterized by a massive increase of reactive oxygen and nitrogen species (ROS/RNS) and mitochondrial dysfunction. Despite intensive research, determining events in the progression or reversal of the disease are incompletely understood. Herein, we studied two prototype sepsis models: endotoxemia and cecal ligation and puncture (CLP)-which showed very different lethality rates (2.5% and 67%, respectively)-, evaluated iNOS, ROS and respiratory chain activity, and investigated mitochondrial biogenesis and dynamics, as possible processes involved in sepsis outcome. Endotoxemia and CLP showed different iNOS, ROS/RNS, and complex activities time-courses. Moreover, these alterations reverted after 24-h endotoxemia but not after CLP. Mitochondrial biogenesis was not elicited during the first 24 h in either model but instead, 50% mtDNA depletion was observed. Mitochondrial fusion and fission were evaluated using real-time PCR of mitofusin-2 (Mfn2), dynamin-related protein-1 (Drp1), and using electron microscopy. During endotoxemia, we observed a decrease of Mfn2-mRNA levels at 4-6 h, and an increase of mitochondrial fragmentation at 6 h. These parameters reverted at 24 h. In contrast, CLP showed not only decreased Mfn2-mRNA levels at 12-18 h but also increased Drp1-mRNA levels at 4 h, and enhanced and sustained mitochondrial fragmentation. The in vivo pretreatment with mdivi-1 (Drp1 inhibitor) significantly attenuated mitochondrial dysfunction and apoptosis in CLP. Therefore, abnormal fusion-to-fission balance, probably evoked by ROS/RNS secondary to iNOS induction, contributes to the progression of sepsis. Pharmacological targeting of Drp1 may be a potential novel therapeutic tool for sepsis.

Modulation of liver mitochondrial NOS is implicated in thyroid-dependent regulation of O(2) uptake.

Changes in O(2) uptake at different thyroid status have been explained on the basis of the modulation of mitochondrial enzymes and membrane biophysical properties. Regarding the nitric oxide (NO) effects, we tested whether liver mitochondrial nitric oxide synthase (mtNOS) participates in the modulation of O(2) uptake in thyroid disorders. Wistar rats were inoculated with 400 microCi (131)I (hypothyroid group), 20 microg thyroxine (T(4))/100 g body wt administered daily for 2 wk (hyperthyroid group) or vehicle (control). Basal metabolic rate, mitochondrial function, and mtNOS activity were analyzed. Systemic and liver mitochondrial O(2) uptake and cytochrome oxidase activity were lower in hypothyroid rats with respect to controls; mitochondrial parameters were further decreased by L-arginine (-42 and -34%, P < 0.05), consistent with 5- to 10-fold increases in matrix NO concentration. Accordingly, mtNOS expression (75%) and activity (260%) were selectively increased in hypothyroidism and reverted by hormone replacement without changes in other nitric oxide isoforms. Moreover, mtNOS activity correlated with serum 3,5,3'-triiodothyronine (T(3)) and O(2) uptake. Increased mtNOS activity was also observed in skeletal muscle mitochondria from hypothyroid rats. Therefore, we suggest that modulation of mtNOS is a substantial part of thyroid effects on mitochondrial O(2) uptake.

Nitric oxide regulates oxygen uptake and hydrogen peroxide release by the isolated beating rat heart.

Isolated rat heart perfused with 1.5-7.5 microM NO solutions or bradykinin, which activates endothelial NO synthase, showed a dose-dependent decrease in myocardial O2 uptake from 3.2 +/- 0.3 to 1.6 +/- 0.1 (7.5 microM NO, n = 18, P < 0.05) and to 1.2 +/- 0.1 microM O2.min-1.g tissue-1 (10 microM bradykinin, n = 10, P < 0.05). Perfused NO concentrations correlated with an induced release of hydrogen peroxide (H2O2) in the effluent (r = 0.99, P < 0.01). NO markedly decreased the O2 uptake of isolated rat heart mitochondria (50% inhibition at 0.4 microM NO, r = 0.99, P < 0.001). Cytochrome spectra in NO-treated submitochondrial particles showed a double inhibition of electron transfer at cytochrome oxidase and between cytochrome b and cytochrome c, which accounts for the effects in O2 uptake and H2O2 release. Most NO was bound to myoglobin; this fact is consistent with NO steady-state concentrations of 0.1-0.3 microM, which affect mitochondria. In the intact heart, finely adjusted NO concentrations regulate mitochondrial O2 uptake and superoxide anion production (reflected by H2O2), which in turn contributes to the physiological clearance of NO through peroxynitrite formation.

Characteristics of neutrophil influx in rat lungs following fecal peritonitis.

Neutrophil accumulation in rat lungs during fecal peritonitis was estimated by the increase in myeloperoxidase content. The oxidative response of lung neutrophils was monitored as the increase in low-level chemiluminescence from intact lungs, before and after stimulation by phorbol myristate acetate (PMA). Myeloperoxidase activity increased 20-fold within 6 h of the surgical procedure, declining over the next 10 h to 12 times control. There was no significant increase over controls in either bronchoalveolar lavage protein or spontaneous chemiluminescence unless neutrophils were stimulated by PMA. When neutrophils were stimulated with PMA, lung chemiluminescence was not proportional to neutrophil content. The oxidative response increased as sepsis progressed from 51 +/- 4.5 cps/pair lungs in controls to 410 +/- 204 at 16 h after surgery, even though at that time point myeloperoxidase content had begun to decrease. The oxidative response of bronchoalveolar lavage cells was threefold greater in 16-h septic rats than in controls.

Oxidative stress in skeletal muscle during sepsis in rats.

Skeletal muscle is a target organ during sepsis; nevertheless, there is no evidence of a possible free radical overproduction with tissue damage in this situation. We studied Sprague Dawley female rats in two groups: a septic group with cecal ligation and double cecal perforation and a control group that was sham operated. Hind limb adductor muscles spontaneous chemiluminescence was measured at 2, 4, 6, 12, 24, and 30 hr after the surgical procedure as the expression of oxygen excited species generation. Muscle samples were also taken and activity of the principal antioxidant enzymes--superoxide dismutase (SOD), catalase, and glutathione peroxidase--as well as myeloperoxidase, an index of neutrophil infiltration was determined. CPK seric assays at 12 and 24 hr were used to reflect muscle injury and revealed high levels. Previously administered bovine superoxide dismutase was employed to prevent or attenuate oxidative stress. The results showed that light emission by rat skeletal muscle doubled from 4 to 12 hr of sepsis and could be attenuated with SOD pretreatment. Observed changes may be attributed to the production of oxygen free radicals that do not depend on local neutrophil infiltration. The detoxifying antioxidant enzyme activities in skeletal muscle were diminished (Mn SOD 46% at 6 hr, catalase 83% at 12 hr glutathione peroxidase 55% at 12 hr), which would also facilitate muscle septic damage.

Captopril versus hydralazine in primary pulmonary hypertension.

Captopril was tested as the treatment for a patient with primary pulmonary hypertension (PPH) and its effects were compared with those of hydralazine. Captopril induced a rise in pulmonary pressures and in intrapulmonary shunt; hydralazine lowered pulmonary resistances and increased paO2 and blood O2 transport. Prospective studies in PPH treated with captopril are recommended and evaluation of all drugs not only by hemodynamic but also respiratory and O2 transport measurements.

Shock no asociado a deplecion hidrosalina en un caso de insuficiencia suprarrenal de etiologia metastasica. / Shock non associated with hydrosaline depletion in a case of adrenal gland insufficiency of metastasic etiology

Se presenta el caso de una paciente de 46 anos portadora de un carcinoma pulmonar con metastasis suprarrenales bilaterales que reemplazan casi totalmente las glandulas. El diagnostico se confirmo por la tomografia computada y los hallazgos necropsicos. Se trata de un caso poco comun de insuficiencia suprarrenal que reune un estado de colapso circulatorio junto a edemas. Se jerarquiza el rol de la falta de cortisol en la genesis de los fenomenos descriptos debido a que no pudo corregirse el shock con la administracion de cloruro de sodio en solucion al 0,9% o con la infusion de dopamina, pero si ocurrio luego de la administracion de hidrocortisona intravenosa

Shock no asociado a deplecion hidrosalina en un caso de insuficiencia suprarrenal de etiologia metastasica. / Shock non associated with hydrosaline depletion in a case of adrenal gland insufficiency of metastasic etiology

Se presenta el caso de una paciente de 46 anos portadora de un carcinoma pulmonar con metastasis suprarrenales bilaterales que reemplazan casi totalmente las glandulas. El diagnostico se confirmo por la tomografia computada y los hallazgos necropsicos. Se trata de un caso poco comun de insuficiencia suprarrenal que reune un estado de colapso circulatorio junto a edemas. Se jerarquiza el rol de la falta de cortisol en la genesis de los fenomenos descriptos debido a que no pudo corregirse el shock con la administracion de cloruro de sodio en solucion al 0,9% o con la infusion de dopamina, pero si ocurrio luego de la administracion de hidrocortisona intravenosa