RESUMEN
Coagulation abnormalities have been implicated in the pathogenesis of sepsis and organ dysfunction. Nitric oxide (NO) is regarded as a critical mediator of many vascular pathologies, including sepsis. However, limited evidence is available to document a relationship between NO generated by inducible NO synthase (iNOS) and hemostatic abnormalities in sepsis. Therefore, we evaluated the effects of selective iNOS inhibition on markers of endothelial and coagulation homeostasis in a clinically relevant model of porcine bacteremia induced and maintained for 24 hours (h) with a continuous infusion of live P. aeruginosa. After 12 h of sepsis, animals received either vehicle (Control, n=7) or continuous infusion of selective iNOS inhibitor L-NIL (n=7). Before as well as 12, 18 and 24 h after starting P. aeruginosa following variables related to i) endothelial dysfunction (von Willebrand factor [vWf]; tissue plasminogen activator activity [t-PA]; ii) coagulation (thrombin-antithrombin complexes [TAT]; platelet count); iii) fibrinolysis (t-PA activity, activity of plasminogen activator inhibitor type 1 (PAI-1 act); and iv) oxidative/nitrosative stress (isoprostanes, nitrate/nitrite levels) were measured. L-NIL inhibited sepsis-induced increase in plasma nitrate/nitrite and isoprostanes concentrations, prevented hypotension and acidosis. L-NIL significantly attenuated sepsis-induced rise in plasma vWF and TAT. P. aeruginosa-induced drop in t-PA activity was blunted by iNOS inhibition, while increased PAI-1 and reduced platelet count were not reversed by the treatment. In conclusion, selective iNOS inhibition was associated with attenuation of sepsis-induced coagulation and endothelial dysfunction suggesting the interplay between mediators of vascular system and hemostatic balance. Reduction of oxidative stress probably contributes to the beneficial effects afforded by iNOS blockade.
Asunto(s)
Bacteriemia/sangre , Coagulación Sanguínea/efectos de los fármacos , Endotelio Vascular/efectos de los fármacos , Inhibidores Enzimáticos/farmacología , Lisina/análogos & derivados , Óxido Nítrico Sintasa de Tipo II/antagonistas & inhibidores , Infecciones por Pseudomonas/sangre , Equilibrio Ácido-Base/efectos de los fármacos , Animales , Bacteriemia/metabolismo , Bacteriemia/microbiología , Bacteriemia/fisiopatología , Sistema Cardiovascular/efectos de los fármacos , Modelos Animales de Enfermedad , Endotelio Vascular/metabolismo , Endotelio Vascular/fisiopatología , Fibrinógeno/efectos de los fármacos , Lisina/farmacología , Óxido Nítrico/metabolismo , Óxido Nítrico Sintasa de Tipo II/metabolismo , Estrés Oxidativo/efectos de los fármacos , Infecciones por Pseudomonas/metabolismo , Infecciones por Pseudomonas/microbiología , Infecciones por Pseudomonas/fisiopatología , Pseudomonas aeruginosa , Porcinos , Factores de TiempoRESUMEN
Complex interactions of nitric oxide and other free radicals have been implicated in the pathogenesis of sepsis and organ dysfunction. We hypothesized that simultaneous inducible nitric oxide synthase inhibition (L-N6-[1-iminoethyl]-lysine [L-NIL]) and neutralization of superoxide (O2-) (4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl [Tempol]) would protect from detrimental consequences of long-term, volume-resuscitated, hyperdynamic porcine bacteremia. In this prospective, randomized, controlled experimental study, 16 anesthetized, mechanically ventilated and instrumented pigs were exposed to 24 h of continuous infusion of live Pseudomonas aeruginosa. After 12 h of hyperdynamic sepsis, animals were randomized to receive either vehicle (control, n = 8) or combination of L-NIL and Tempol (n = 8). Systemic and hepatosplanchnic hemodynamics, oxygen exchange, metabolism, ileal mucosal microcirculation and tonometry, oxidative stress and coagulation parameters were assessed before, 12, 18, and 24 h of P. aeruginosa infusion. Combined treatment inhibited sepsis-induced increase in plasma nitrate/nitrite, 8-isoprostane, and thiobarbituric acid reactive species concentrations, prevented hypotension, and reversed hyperdynamic circulation. Despite lower intestinal macrocirculation, combined regimen attenuated the otherwise progressive deterioration in ileal mucosal microcirculation and prevented mucosal acidosis. Treatment substantially attenuated mesenteric and hepatic venous acidosis, preserved sepsis-induced impairment of hepatosplanchnic redox state, and prevented the development of renal dysfunction. Finally, coinfusion of L-NIL and Tempol largely attenuated the sepsis-induced rise in plasma von Willebrand factor and thrombin-antithrombin complexes. Thus, hemodynamic, microcirculatory, metabolic, renal, and coagulation data indicate that combining inducible inhibition with cell permeable O2(-) radical scavenger afforded significant protection in porcine sepsis, thus suggesting an important interactive role of O2(-) and nitric oxide in mediating organ dysfunction.
Asunto(s)
Bacteriemia/tratamiento farmacológico , Óxidos N-Cíclicos/farmacología , Depuradores de Radicales Libres/farmacología , Óxido Nítrico Sintasa de Tipo II/antagonistas & inhibidores , Infecciones por Pseudomonas/tratamiento farmacológico , Porcinos/microbiología , Animales , Bacteriemia/fisiopatología , Infecciones por Pseudomonas/fisiopatología , Pseudomonas aeruginosa/fisiología , Marcadores de Spin , Porcinos/fisiologíaRESUMEN
BACKGROUND: Brain natriuretic peptide (BNP) and N-terminal proBNP (NT-proBNP) are released into circulation as a result of congestive heart failure (HF). As HF and water overload are frequent complications in haemodialysis (HD) patients, we decided to study the levels of BNP and NT-proBNP and their changes during HD. METHODS: BNP and NT-proBNP levels were determined in 94 HD patients before and after a regular 4-h HD. We followed changes in these peptides during HD depending on age, sex, HF (NYHA classification and left ventricular ejection fraction [LVEF]), duration on HD, presence of hypertension, coronary artery disease, type of membrane used for HD [low-flux (LFx) or high-flux (HFx)] and body mass change during HD. Furthermore, patients basic medication and creatinine levels and presence of diabetes mellitus were monitored. RESULTS: Respectively,94% and 100% of the patients had pre-dialysis concentrations of BNP and NT-proBNP above the cut-off values for HF. The marker levels correlated significantly both before and after HD (r = 0.903 and 0.888, respectively, p < 0.001). BNP levels significantly decreased (p < 0.0001), whereas NT-proBNP significantly increased (p < 0.0001) during HD on LFx membranes. HD on HFx membranes caused greater decrease of BNP (compared to LFx membranes, p < 0.001), but also a decrease of NT-proBNP (p < 0.001).We did not find any significant differences in marker levels for HF and non-HF patients (NYHA classification). However, both peptides reached higher levels in the group with LVEF < or = 50% (p < 0.001 for both peptides). Body mass change during HD negatively correlated only with the change of NT-proBNP (r = -0.27, p < 0.05). In the multiple regression model, the change of both peptides during HD was significantly influenced by membrane type (p = 0.003 for BNP and p = 0.001 for NT-proBNP). NT-proBNP change during HD was further significantly influenced by LVEF (p = 0.012), sex (p = 0.002) and duration on HD (p = 0.006). CONCLUSIONS: Both BNP and NT-proBNP levels were significantly increased in HD patients prior to dialysis. The change in concentrations of both peptides during HD is influenced by membrane type. HD probably triggers increased production of both peptides and this increase is emphasized by impaired LVEF. This fact can be clinically observed only on NT-proBNP levels, because BNP levels are biased by significant removal of this protein during HD.
Asunto(s)
Insuficiencia Cardíaca/sangre , Insuficiencia Cardíaca/epidemiología , Fallo Renal Crónico/sangre , Péptido Natriurético Encefálico/sangre , Fragmentos de Péptidos/sangre , Diálisis Renal , Anciano , Índice de Masa Corporal , Comorbilidad , Femenino , Humanos , Fallo Renal Crónico/epidemiología , Fallo Renal Crónico/terapia , Masculino , Persona de Mediana Edad , Análisis de Regresión , Disfunción Ventricular Izquierda/epidemiologíaRESUMEN
OBJECTIVES: Pretreatment with tempol, a membrane-permeable radical scavenger, has been shown to be protective in rodent models of endotoxic and Gram-positive shock. However, neither the pretreatment design nor hypodynamic endotoxic shock in rodents mimics the clinical scenario. Therefore, we investigated the effects of tempol in a posttreatment model of long-term, volume-resuscitated, hyperdynamic porcine bacteremia. DESIGN: Prospective, randomized, controlled experimental study. SETTING: University animal laboratory. SUBJECTS: Sixteen anesthetized, mechanically ventilated, and instrumented pigs. INTERVENTIONS: Sepsis was induced and maintained for 24 hrs with continuous infusion of live Pseudomonas aeruginosa. After 12 hrs of hyperdynamic sepsis, animals were randomized to receive either vehicle (control, n = 8) or continuous infusion of tempol (n = 8, 30 mg/kg/hr). MEASUREMENTS AND MAIN RESULTS: Systemic and hepatosplanchnic hemodynamics, oxygen exchange, metabolism, ileal mucosal microcirculation, and tonometry as well as oxidative stress and coagulation variables were assessed before and after 12, 18, and 24 hrs of P. aeruginosa infusion. Tempol significantly attenuated reduction in mean arterial pressure. Despite comparable mesenteric macrocirculation, tempol attenuated the otherwise progressive deterioration in ileal mucosal microcirculation and prevented mucosal acidosis. By contrast, treatment with tempol failed to influence the P. aeruginosa-induced derangements of hepatosplanchnic redox state, liver lactate clearance, and regional acidosis but prevented the development of renal dysfunction. In addition, tempol reduced nitrosative stress without significant effect on the gradual increase in plasma 8-isoprostanes. Finally, tempol attenuated sepsis-induced endothelial (von Willebrand factor) and hemostatic dysfunction (thrombin-antithrombin complexes, plasminogen activator inhibitor-type 1). CONCLUSIONS: The radical scavenger tempol partially prevented live bacteria from causing key features of hemodynamic and metabolic derangements in porcine hyperdynamic sepsis and beneficially affected surrogate markers of sepsis-induced endothelial and coagulation dysfunction. Incomplete reduction of oxidative stress because of dilutional effects and/or missed optimal therapeutic window for antioxidant treatment when used in posttreatment approach may account for the only partial protection by tempol in this model.
Asunto(s)
Antioxidantes/uso terapéutico , Bacteriemia/tratamiento farmacológico , Óxidos N-Cíclicos/uso terapéutico , Hígado/efectos de los fármacos , Animales , Antioxidantes/farmacología , Bacteriemia/metabolismo , Bacteriemia/fisiopatología , Coagulación Sanguínea/efectos de los fármacos , Presión Sanguínea/efectos de los fármacos , Óxidos N-Cíclicos/farmacología , Metabolismo Energético , Femenino , Frecuencia Cardíaca/efectos de los fármacos , Hígado/metabolismo , Masculino , Microcirculación/efectos de los fármacos , Estrés Oxidativo/efectos de los fármacos , Marcadores de Spin , PorcinosRESUMEN
We have recently demonstrated that selective inducible nitric oxide (NO) synthase (iNOS) inhibition with 1400W attenuated the hemodynamic and metabolic alterations affiliated with hyperdynamic porcine endotoxemia. In contrast to endotoxemia, limited evidence is available to document a relationship between NO and organ dysfunction in large animal bacteremic models. Therefore, using the same experimental setup, we investigated the role of selective iNOS blockade in porcine bacteremia induced and maintained for 24 h with a continuous infusion of live Pseudomonas aeruginosa. After 12 h of sepsis, animals received either vehicle (Control, n = 8) or continuous infusion of selective iNOS inhibitor, L-N6-(1-iminoethyl)-lysine (L-NIL; n = 8). Measurements were performed before, and 12, 18, and 24 h after P. aeruginosa infusion. L-NIL inhibited sepsis-induced increase in plasma nitrate/nitrite concentrations and prevented hypotension without affecting cardiac output. Despite comparable hepatosplanchnic macrocirculation, L-NIL blunted the progressive deterioration in ileal mucosal microcirculation and prevented mucosal acidosis. L-NIL largely attenuated mesenteric and hepatic venous acidosis, significantly improved P. aeruginosa-induced impairment of hepatosplanchnic redox state, and mitigated the decline in liver lactate clearance. Furthermore, the administration of L-NIL reduced the hepatocellular injury and prevented the development of renal dysfunction. Finally, treatment with L-NIL significantly attenuated the formation of 8-isoprostane concentrations, a direct marker of lipid peroxidation. Thus, selective iNOS inhibition with L-NIL prevented live bacteria from causing key features of metabolic derangements in porcine hyperdynamic sepsis. Underlying mechanisms probably include reduced oxidative stress with improved microcirculatory perfusion and restoration of cellular respiration.