Function Of Fibronectin In Throm Bokinesis And Its Clinical Significance

Objective (1) To study and research mechanisms of fibronectin(Fn) anchoring platelet-surface and investigate its role in platelet thrombokinesis; (2) To detect plasma Fn levels and expression of platelet binding Fn from platelet-surface in acute myocardial infarction(AMI) patients before and after healing and normal subjects, to provide a new way for early diagnosis and pathogenetic condition prognosis analysis in AMI patients.Methods (1) Venous blood was collected from seventeen patients with AMI before healing, twelve patients with AMI after healing, and thirteen normal subjects into acid citrate dextrose anticoagulant. Washed human platelets were prepared by gel filtration on Sepharose 2B and finally resuspended in the PIPES buffer at 5×10~7 platelets/ml, platelet suspensions be dividatured into resting group, intracytoplasm group, thrombin(TT) stimulated group, and thrombin receptor-activating Peptides(TRAP) stimulated group. Percentage of platelets binding Fn were analysed by flow cytometry(FCM); (2) Expression of Fn bound to platelet-surface from AMI patients before and after healing and normal subjects by immunofluores staining; (3) Plasma Fn levels in AMI patients before and after healing and normal subjects detect by enzyme-linked immunosorbent Asszy(ELISA).Results (1) FCM detected the expression of Fn bound to platelet-surface in normal subjects were 14.35±5.31%, but in platelet intracytoplasm were 74.52± 15.52%, the expression of Fn bound to platelet-surface by TTstimulated were 56.79±19.15%, indicating a higher expression of Fn on platelet membrance with TT stimulated platelet than unstinulated platelet (P< 0.001) , the expression of Fn bound to platelet-surface by TRAP were 26.4±7.89%, its percentage were higher than unstinulated platelet, but obviously lower than TT stimulated platelet ( P< 0.001) ;(2) The expression of Fn on platelet membrance were 66.19±17.45% in AMI patients before healing, while those in AMI patients after healing were 14.35±5.31%, indicating a higher expression of Fn on platelet membrance in AMI patients before healing than after healing (P< 0.001 ) ; (3) Fluorescence intensity of Fn bound to platelet-surface from AMI patients before healing was superlative bright, but only a very light staining in AMI patients after healing and normal subjects; (4) Plasma Fn levels in normal subjects were 361.54±68.48 mg/1 by ELISA, but in AMI patients before healing were 449±139.11mg/l and after healing were 33O±55.3 mg/l, indicating a higher plasma Fn level in patients with AMI before healing than in control group (P< 0.001) ,but there were no different between AMI after healing and normal subjects (P>0.05) .Conclusions (1) There were low expression of platelet binding Fn from platelet-surface but high expression in platelet intracytoplasm, expression of platelet binding Fn from platelet-surface were step up after TT stimulation, indicating platelets contain a pool of endogenous Fn that can be released and may bind to surface membrane under TT stimulate, hint that Fn may also be involved in platelet adhesion and aggregation, serve as a scaffold for platelet thrombus formation process. (2) TRAP have a function of TT stimulate platelet, but no function of TT conversion fibrinogen(Fg) to fibrin(Fib), there were high expression of platelet binding Fn from...