3-nitrotyrosine and Airway-Obstruction

Neuronal nitric oxide synthase is critically involved in the pathogenesis of acute lung injury resulting from combined burn and smoke inhalation injury. We hypothesized that 7-nitroindazole, a selective neuronal nitric oxide synthase inhibitor, blocks central molecular mechanisms involved in the pathophysiology of this double-hit insult. Twenty-five adult ewes were surgically prepared and randomly allocated to 1) an uninjured, untreated sham group (n = 7), 2) an injured control group with no treatment (n = 7), 3) an injury group treated with 7-nitroindazole from 1-h postinjury to the remainder of the 24-h study period (n = 7), or 4) a sham-operated group subjected only to 7-nitroindazole to judge the effects in health. The combination injury was associated with twofold increased activity of neuronal nitric oxide synthase and oxidative/nitrosative stress, as indicated by significant increases in plasma nitrate/nitrite concentrations, 3-nitrotyrosine (an indicator of peroxynitrite formation), and malondialdehyde lung tissue content. The presence of systemic inflammation was evidenced by twofold, sixfold, and threefold increases in poly(ADP-ribose) polymerase, IL-8, and myeloperoxidase lung tissue concentrations, respectively (each P < 0.05 vs. sham). These molecular changes were linked to tissue damage, airway obstruction, and pulmonary shunting with deteriorated gas exchange. 7-Nitroindazole blocked, or at least attenuated, all these pathological changes. Our findings suggest 1) that nitric oxide formation derived from increased neuronal nitric oxide synthase activity represents a pivotal reactive agent in the patho-physiology of combined burn and smoke inhalation injury and 2) that selective neuronal nitric oxide synthase inhibition represents a goal-directed approach to attenuate the degree of injury.

Topics: Airway Obstruction; Animals; Cell Nucleus; Enzyme Activation; Hemodynamics; Indazoles; Interleukin-8; Lung Injury; Malondialdehyde; Nitrates; Nitric Oxide Synthase Type I; Nitrites; Peroxidase; Poly(ADP-ribose) Polymerases; Pressure; Regional Blood Flow; Respiratory Function Tests; Sheep; Survival Analysis; Trachea; Transcription Factor RelA; Tyrosine

Thermal injury results in reduced plasma levels of arginine (Arg). With reduced Arg availability, NOS produces superoxide instead of NO. We hypothesized that Arg supplementation after burn and smoke inhalation (B + S) injury would attenuate the acute insult to the lungs and, thus, protect pulmonary function. Seventeen Suffolk ewes (n = 17) were randomly divided into three groups: (1) sham injury group (n = 6), (2) B + S injury plus saline treatment (n = 6), and (3) B + S injury plus L-ARG infusion at 57 mg.kg(-1).h(-1) (n = 5). Burn and smoke inhalation injury was induced by standardized procedures, including a 40% area full thickness flame burn combined with 48 breaths of smoke from burning cottons. All animals were immediately resuscitated by Ringer solution and supported by mechanical ventilation for 48 h, during which various variables of pulmonary function were monitored. The results demonstrated that Arg treatment attenuated the decline of plasma Arg concentration after B + S injury. A higher plasma Arg concentration was associated with a less decline in Pao2/Fio2 ratio and a reduced extent of airway obstruction after B + S injury. Histopathological examinations also indicated a remarkably reduced histopathological scores associated with B + S injury. Nitrotyrosine stain in lung tissue was positive after B + S injury, but was significantly reduced in the group with Arg. Therefore, L-Arg supplementation improved gas exchange and pulmonary function in ovine after B + S injury via its, at least in part, effect on reduction of oxidative stress through the peroxynitrite pathway.

Topics: Airway Obstruction; Animals; Arginine; Blood Pressure; Burns; Female; Hematocrit; Lung; Lung Injury; Nitrates; Nitrites; Random Allocation; Sheep; Smoke Inhalation Injury; Survival Analysis; Tyrosine; Urination

To investigate the effects of recombinant human activated protein C (rhAPC) on pulmonary function in acute lung injury (ALI) resulting from smoke inhalation in association with a bacterial challenge.. Prospective, randomized, controlled, experimental animal study with repeated measurements.. Investigational intensive care unit at a university hospital.. Eighteen sheep (37.2 +/- 1.0 kg) were operatively prepared and randomly allocated to either the sham, control, or rhAPC group (n = 6 each). After a tracheotomy had been performed, ALI was produced in the control and rhAPC group by insufflation of 4 sets of 12 breaths of cotton smoke. Then, a 30 mL suspension of live Pseudomonas aeruginosa bacteria (containing 2-5 x 10(11) colony forming units) was instilled into the lungs according to an established protocol. The sham group received only the vehicle, i.e., 4 sets of 12 breaths of room air and instillation of 30 mL normal saline. The sheep were studied in the awake state for 24 hrs and were ventilated with 100% oxygen. RhAPC (24 mug/kg/hr) was intravenously administered. The infusion was initiated 1 hr post-injury and lasted until the end of the experiment. The animals were resuscitated with Ringer's lactate solution to maintain constant pulmonary artery occlusion pressure.. In comparison with nontreatment in controls, the infusion of rhAPC significantly attenuated the fall in Pao2/Fio2 ratio (control group values were 521 +/- 22 at baseline [BL], 72 +/- 5 at 12 hrs, and 74 +/- 7 at 24 hrs, vs. rhAPC group values of 541 +/- 12 at BL, 151 +/- 29 at 12 hours [p < .05 vs. control], and 118 +/- 20 at 24 hrs), and significantly reduced the increase in pulmonary microvascular shunt fraction (Qs/Qt; control group at BL, 0.14 +/- 0.02, and at 24 hrs, 0.65 +/- 0.08; rhAPC group at BL, 0.24 +/- 0.04, and at 24 hrs, 0.45 +/- 0.02 [p < .05 vs. control]) and the increase in peak airway pressure (mbar; control group at BL, 20 +/- 1, and at 24 hrs, 36 +/- 4; rhAPC group at BL, 21 +/- 1, and at 24 hrs, 28 +/- 2 [p < .05 vs. control]). In addition, rhAPC limited the increase in lung 3-nitrotyrosine (after 24 hrs [%]: sham, 7 +/- 2; control, 17 +/- 1; rhAPC, 12 +/- 1 [p < .05 vs. control]), a reliable indicator of tissue injury. However, rhAPC failed to prevent lung edema formation. RhAPC-treated sheep showed no difference in activated clotting time or platelet count but exhibited less fibrin degradation products (1/6 animals) than did controls (4/6 animals).. Recombinant human activated protein C attenuated ALI after smoke inhalation and bacterial challenge in sheep, without bleeding complications.

Topics: Airway Obstruction; Animals; Blood Pressure; Body Temperature; Disease Models, Animal; Female; Fibrinolytic Agents; Infusions, Intravenous; Lung; Nitrates; Nitrites; Organ Size; Prospective Studies; Protein C; Pulmonary Edema; Random Allocation; Recombinant Proteins; Respiratory Function Tests; Sepsis; Sheep; Smoke Inhalation Injury; Tyrosine