RESUMEN
Hepatorenal syndrome (HRS) is defined as the development of renal insufficiency in chronic liver disease with portal hypertension when other causes of functional renal failure are excluded. Incidence in patients with refractory ascites is 8%, with an overall incidence of renal failure in end stage liver disease being 75%. HRS is predictive for the prognosis of end stage liver failure but its pathogenesis is complex and currently not fully understood.
Asunto(s)
Síndrome Hepatorrenal/patología , Diagnóstico Diferencial , Síndrome Hepatorrenal/diagnóstico , Síndrome Hepatorrenal/fisiopatología , Síndrome Hepatorrenal/terapia , Humanos , Trasplante de Riñón , Trasplante de Hígado , Derivación Portosistémica Quirúrgica , Sistema Renina-Angiotensina/fisiología , Terminología como AsuntoRESUMEN
OBJECTIVES: Several studies have demonstrated altered platelet function during nitric oxide inhalation (iNO) in adults and neonates. In vitro NO inhibits activation of fibrinogen receptor glycoprotein (GP) IIb/IIIa in a dose-dependent manner. In neonates GPIIb/IIIa response to stimulation is physiologically attenuated during the first days after birth in comparison to adults; the effects of NO on GPIIb/IIIa in neonates, however, are less established. We investigated the response of platelets from neonates, their mothers, and nonpregnant controls to the NO donor SIN-1 in vitro. DESIGN: Umbilical cord and venous (mother, controls) platelet-rich plasma was stimulated in vitro with 10 microM ADP or 0.05 U/ml thrombin in the presence or absence of 10 microM SIN-1. GPIIb/IIIa activation was determined by two-color flow cytometry. SETTING: Delivery department of an university hospital. PATIENTS AND PARTICIPANTS: Ten healthy term neonates, their mothers and nonpregnant controls. MEASUREMENTS AND RESULTS: NO significantly reduced GPIIb/IIIa activation in thrombin- and ADP-stimulated platelets in all groups (p < 0.001). Neonatal platelets were significantly hyporeactive to stimulation (p < 0.05), but the relative response to SIN-1 was similar in all three groups (70 +/- 5 %). CONCLUSIONS: The relative amount of NO-induced inhibition of GPIIb/ IIIa activation in neonates is thus similar to that of adults. However, due to the intrinsic hyporesponsiveness of neonatal platelets and NO-synergistic pharmacodynamic profiles of other drugs (e.g., prostacyclin), possible adverse effects of iNO must be considered.
Asunto(s)
Plaquetas/efectos de los fármacos , Sangre Fetal/citología , Molsidomina/farmacología , Donantes de Óxido Nítrico/farmacología , Complejo GPIIb-IIIa de Glicoproteína Plaquetaria/efectos de los fármacos , Adulto , Factores de Edad , Estudios de Casos y Controles , Femenino , Humanos , Técnicas In Vitro , Recién Nacido , Molsidomina/análogos & derivados , Óxido Nítrico/farmacología , Complejo GPIIb-IIIa de Glicoproteína Plaquetaria/metabolismoRESUMEN
BACKGROUND: The absence of a protective endothelial surface on membrane oxygenators during extracorporeal circulation (ECC) promotes platelet trapping and damage, leading to increased bleeding complications. We investigated the effects of transmembranous diffusion of gaseous nitric oxide (NO) on platelets during simulated ECC. MATERIAL AND METHODS: Two paired circuits were run in parallel with fresh, heparinized (1 U mL-1) blood from healthy human donors for 240 min. To one of the paired circuits, 20 ppm NO was added transmembranously. RESULTS: NO significantly attenuated platelet trapping and reduced intracircuit platelet activation evaluated by the release of beta-thromboglobulin, platelet factor 4 and soluble P-selectin. Furthermore, NO significantly preserved platelet reactivity to stimulating agents (ADP and adrenaline), evaluated as the ability to expose P-selectins and activate glycoprotein (GP)-IIb-IIIa. Nevertheless, circulating activated platelets expressing P-selectin or activated GPIIb-IIIa were not different and were not significantly increased. The mean fluorescence intensity of GPIb and GPIIb-IIIa decreased in both circuits equally. CONCLUSIONS: Transmembranous diffusion of gaseous NO revealed protective effects on platelets by reducing thrombocytopenia/pathia and preserving platelet reactivity.
Asunto(s)
Circulación Extracorporea , Óxido Nítrico/metabolismo , Activación Plaquetaria/fisiología , Adenosina Difosfato/farmacología , Agonistas Adrenérgicos/farmacología , Anticuerpos Monoclonales , Análisis de los Gases de la Sangre , Plaquetas/química , Plaquetas/citología , Plaquetas/inmunología , Difusión , Epinefrina/farmacología , Compuestos Ferrosos/metabolismo , Compuestos Ferrosos/farmacología , Citometría de Flujo , Humanos , Metahemoglobina/análisis , Óxido Nítrico/análisis , Selectina-P/análisis , Activación Plaquetaria/efectos de los fármacos , Recuento de Plaquetas , Factor Plaquetario 4/análisis , Complejo GPIIb-IIIa de Glicoproteína Plaquetaria/metabolismo , Complejo GPIb-IX de Glicoproteína Plaquetaria/análisis , Complejo GPIb-IX de Glicoproteína Plaquetaria/inmunología , beta-Tromboglobulina/análisisRESUMEN
OBJECTIVE: Nitric oxide (NO) has antithrombotic properties by regulating platelet function, whereas direct effects on plasmatic coagulation are rarely described. In sepsis and inflammation, when synthesis of NO, oxygen radicals and toxic metabolites is crucial, the expression of tissue factor (TF) on monocytes stimulated by lipopolysaccharides (LPS) induces intravascular coagulation. This study was performed to examine the influence of NO and the NO-dependent metabolite peroxynitrite on LPS-induced TF expression and activity in human monocytes. DESIGN: Experimental study. SETTING: Laboratory for cell biology. METHODS: Human peripheral blood mononuclear cells were isolated from buffy coats by gradient centrifugation. The NO-releasing compounds SIN1 and NOC18 were used under different conditions. TF antigen was assayed by flow cytometry, and its activity by a clotting assay. TF-mRNA was measured by reverse transcriptase polymerase chain reaction (RT-PCR-ELISA). MEASUREMENTS AND RESULTS: Whereas NOC18, a pure NO donor, had no effect, SIN1, releasing both NO and superoxide (O2-), reduced TF expression and activity in a dose- and time-dependent manner; superoxide dismutase (SOD) reversed the SIN1-mediated effect. Adding the O2(-)-deliberating system hypoxanthin/xanthin oxidase (which had no significant effect per se) to NOC18, or using the NO and O2- reaction product peroxynitrite resulted in a reduction of TF expression. RT-PCR-ELISA indicated upregulation of TF-mRNA by SIN1 with a peak at 500 microM; higher doses had less effect. CONCLUSION: These data demonstrate an influence of NO on LPS-induced TF expression in monocytes by prior formation of peroxynitrite; furthermore, the balance between NO and O2- seems to play a crucial role.
Asunto(s)
Depuradores de Radicales Libres/farmacología , Regulación de la Expresión Génica/efectos de los fármacos , Monocitos/efectos de los fármacos , Nitratos/farmacología , Óxido Nítrico/farmacología , Oxidantes/farmacología , Tromboplastina/efectos de los fármacos , Tromboplastina/genética , Relación Dosis-Respuesta a Droga , Evaluación Preclínica de Medicamentos , Citometría de Flujo , Depuradores de Radicales Libres/metabolismo , Humanos , Lipopolisacáridos , Monocitos/inmunología , Monocitos/metabolismo , Óxido Nítrico/metabolismo , Tromboplastina/análisis , Tromboplastina/metabolismoRESUMEN
Nitric oxide (NO) is known as a regulator of platelet function by its anti-adhesive, anti-aggregating, and disaggregating properties. We investigated the modulating effects of the NO-releasing compound SIN-1 (3-morpholino-sydnonimine) on platelet surface glycoprotein (GP) expression during stimulation with human alpha-thrombin. Analysis was performed with two-color flow cytometry using fluoresceine-isothiocyanate (FITC) and phycoerythrin-(PE)-conjugated monoclonal antibodies (MoAbs) directed against GPIb CD42b), GP IIb-IIIa (CD41), P-selectin (CD62P), and MoAb PAC-1 directed against activated GP IIb-IIIa. Preincubation of platelets with SIN-1 (IC50: 1 microM) significantly decreased expression of both total and activated GP IIb-IIIa, and P-selectin in platelets stimulated with thrombin (ED50: 0.05 U/ml), whereas thrombin-induced downregulation of GP Ib was not attenuated. P-selectin expression increased in thrombin-stimulated platelets over time; in contrast, activated GP-IIb-IIIa decreased after an initial peak, indicating that thrombin-induced GP IIb-IIIa activation is spontaneously reversible. SIN-1 reduced P-selectin expression only when added before or at the same time as thrombin, whereas conformationally changed GP-IIb-IIIa was significantly reversed at up to 60 minutes after stimulation by SIN-1. In conclusion, NO attenuates activation marker expression in a dose and time dependent manner. GP-IIb-IIIa is highly sensitive to NO which not only prevents receptor activation but also promotes reversal of activated GP IIb-IIIa complex.
Asunto(s)
Plaquetas/efectos de los fármacos , Óxido Nítrico/farmacología , Trombina/metabolismo , Plaquetas/metabolismo , Regulación hacia Abajo , Humanos , Molsidomina/análogos & derivados , Molsidomina/farmacología , Selectina-P/metabolismo , Inhibidores de Agregación Plaquetaria/farmacología , Complejo GPIIb-IIIa de Glicoproteína Plaquetaria/metabolismo , Complejo GPIb-IX de Glicoproteína Plaquetaria/metabolismo , Trombina/farmacología , Regulación hacia Arriba/efectos de los fármacosRESUMEN
Bleeding during extracorporeal circulation (ECC) is often induced and/or aggravated by thrombocytopenia due to platelet-trapping in hollow fiber membrane oxygenators (HFMO). Nitric oxide (NO) has platelet anti-aggregating and dis-aggregating properties. In a paired system we tested whether gaseous NO, added to the gas compartment of one of two parallel running heparin-bonded HFMO attenuated platelet-trapping. Platelet consumption was markedly reduced in the NO-treated HFMO. These data strongly indicate that the application of gaseous NO could prove a new therapeutical approach to reduce bleeding during ECC, serving as a new way of preventing platelet loss, thus reducing the need for high systemic heparinization.