RESUMEN
Vascular or tissue-type plasminogen activator (plasma t-PA) is the circulating physiological fibrinolytic enzyme of endothelial cell origin which function is regulated by fibrin and a specific inhibitor (PAI). To study the pattern of release of t-PA and the behavior of t-PA-PAI complexes in plasma we determined t-PA activity in 44 healthy subjects before and after 10 min of forearm venous occlusion using a new spectrophotometric solid-phase fibrin-tPA activity assay. The assay is based on 1) the high affinity binding of t-PA to fibrin, and 2) the detection of fibrin-bound t-PA by measuring the release of pNA from a chromogenic substrate in the presence of plasminogen. Values at rest were rather undetectable in plasma (0.05 +/- 0.03 IU/ml, in 23 out of 44 samples) but were positively detected in all the euglobulins: 0.88 +/- 0.68 IU/ml. After venous occlusion the majority of plasmas (36 out of 44) showed a slight increase in t-PA activity (0.65 +/- 0.63 IU/ml) as compared to the important level observed in all the euglobulins (9.78 +/- 9.58 IU/ml). So, the ratio plasma/euglobulin t-PA activity was very low (0.06) and remained identical in both pre- and postocclusion samples. However, when diluted plasmas were tested the inhibitory effect disappeared and t-PA activity increased indicating that although t-PA circulates in a neutralized state it can be available for fibrinolysis.(ABSTRACT TRUNCATED AT 250 WORDS)
Asunto(s)
Glicoproteínas/sangre , Activador de Tejido Plasminógeno/sangre , Enfermedades Vasculares/sangre , Adulto , Fibrina , Humanos , Técnicas In Vitro , Cinética , Inactivadores Plasminogénicos , Espectrofotometría/métodosAsunto(s)
Espectrofotometría/métodos , Activador de Tejido Plasminógeno/análisis , Activador de Plasminógeno de Tipo Uroquinasa/análisis , Anticuerpos , Fibrina/fisiología , Gelatina/farmacología , Humanos , Concentración de Iones de Hidrógeno , Unión Proteica , Activador de Tejido Plasminógeno/inmunología , Activador de Plasminógeno de Tipo Uroquinasa/inmunologíaRESUMEN
A method of dosage of X Ag factor by laser immunonephelemetry is proposed. This technique, carried out with a rabbit antiserum in the presence of PEG and EDTA, presents the advantage to be sensitive, reproducible and mostly faster than the other immunological methods, such as Electroimmunodiffusion (EID) and Enzyme Linked Immuno-Sorbent Assay (ELISA). It constitutes a simple tool, applicable in the demonstration of an enzyme dysfunction or liver pathology. Finally, it could bring a supplement of information in monitoring antivitamin K therapy.