Platelets stimulate endothelial cells to synthesize type 1 plasminogen activator inhibitor. Evaluation of the role of transforming growth factor beta.

A model system consisting of thrombin-stimulated bovine platelet releasates (PRthr) and bovine aortic endothelial cells (BAEs) was developed to determine if the interaction between platelets and endothelial cells regulates fibrinolysis. Zymographic analysis indicated that PRthr treatment of BAEs decreases urokinase and increases type 1 plasminogen activator inhibitor (PAI-1) activity. Although PRthr did not affect the overall rate of BAE protein synthesis, it increased PAI-1 biosynthesis within 6 hours. This increase was complete by 12 hours, with maximum stimulation at 10 to 15 micrograms/mL PRthr (1 microgram approximately 10(7) platelets). Neutralizing antibodies to transforming growth factor beta (TGF beta) reduced this effect by 75%. Treatments that activate latent TGF beta (eg, acidification or plasmin) increased this effect approximately fivefold, suggesting that TGF beta in PRthr exists in both a latent (approximately 80%) and an active (approximately 20%) form. In contrast to PRthr, adenosine diphosphate-prepared platelet releasates did not increase PAI-1 synthesis before acidification, indicating that they contain only the latent form of TGF beta. These results suggest that platelets can modulate the fibrinolytic system of the endothelium through the release of TGF beta, and that the mechanism by which the platelets are activated can influence the relative amount of active TGF beta.     

Presence of active and latent type 1 plasminogen activator inhibitor associated with porcine platelets.

Data from a number of laboratories indicate that human platelets contain type I plasminogen activator inhibitor (PAI-1) primarily in a latent form; however, one report (Biochemistry 28:5773, 1989) indicated that it is predominantly the active form of PAI-1 that is present in and can be purified from an ammonium sulfate precipitate of porcine platelets. To clarify this situation, we investigated and compared the status of PAI-1 in porcine and human platelets. Immunologic analysis of the ability of PAI-1 to form complexes with immobilized t-PA indicated that porcine and human platelets contained 3.7 +/- 0.4 and 1.7 +/- 0.3 U of PAI activity per 10(8) platelets (n = 6; +/- SD), respectively; sodium dodecyl sulfate (SDS)-activation of the lysates increased PAI-1 activity to 10.8 +/- 3.0 and 3.8 +/- 0.5 U per 10(8) platelets. Platelet lysates were also treated with an excess of soluble t-PA, which formed complexes with active PAI-1, whereas the latent form was detected by SDS-polyacrylamide gel electrophoresis and reverse fibrin autography. Furthermore, immobilized t-PA was able to deplete active PAI-1 from the platelet extracts, and the latent form remaining in the absorbed extract could be quantitated by activation with 4 mol/L guanidine. To investigate the differences between our observations and the published data, porcine platelets were extracted, and PAI-1 was partially purified as described in the literature. For quantitative analysis, porcine platelet PAI-1 was also purified to homogeneity using standard chromatographic procedures optimized in our laboratory for endothelial PAI-1, and the purified protein was used to develop an enzyme-linked immunoabsorbent assay for porcine PAI-1 antigen. Our results indicate that: (1) latent PAI-1 in concentrated ammonium sulfate precipitates of porcine platelet lysates cannot be detected unless the precipitates are diluted before treatment with denaturants; and (2) active and latent porcine platelet PAI-1 can be separated by gel filtration over molecular sieving columns. In summary, this report documents that PAI-1 in porcine platelets is present in both an active and a latent form.     

Improvement by the insulin-sensitizing agent, troglitazone, of abnormal fibrinolysis in type 2 diabetes mellitus

This study evaluated abnormal fibrinolysis in diabetic patients in terms of the pathophysiological significance and reversibility by oral hypoglycemic agents. Forty-seven patients with type 2 diabetes mellitus were randomly treated for 4 weeks with glibenclamide (n = 23) or troglitazone (n = 24). Before and after treatment, glycemic control, steady-state plasma glucose and insulin (SSPG and SSPI, respectively), and markers of fibrinolysis (tissue plasminogen activator [tPA] and plasminogen activator inhibitor-1 [PAI-1]) were analyzed in each patient. Pretreatment plasma PAI-1 in diabetic patients, but not tPA, was well correlated with the severity of retinopathy assessed by the fluorescence technique. Four weeks of treatment with troglitazone significantly decreased hemoglobin A1c (HbA1c), SSPG, and PAI-1 without an alteration of tPA. The troglitazone-induced decrease in plasma PAI-1 (50.3 v28.8 micromol/L; P < .05) was correlated with HbA1c (8.80% v7.21%, r = .539, P < .01) and SSPG (16.2 v 8.97 mmol/L, r = .562, P < .01) but not with SSPI. In contrast, treatment with glibenclamide for 4 weeks also reduced the HbA1c titer to almost the same extent as troglitazone (1.38% v 1.59%), but did not change the plasma PAI-1 or SSPG titer. These results suggest that an abnormal fibrinolytic state, especially overproduction of PAI-1, may be a pathogenic factor in the development of diabetic complications such as retinopathy, which may be improved by correction of the insulin resistance with troglitazone.     

纤维蛋白原、纤维蛋白及其降解产物对共培养血管内皮细胞纤溶活性的影响

目的研究纤维蛋白原（Fg）、纤维蛋白（Fb）及其降解产物（FDP）对共培养体系中人脐静脉内皮细胞组织型纤溶酶原激活物和纤溶酶原激活物抑制剂表达的影响。方法应用Transwell膜建立人脐静脉内皮细胞-兔主动脉平滑肌细胞共培养体系，在不同浓度（0、0．5、1．5、3．0、4．5和6．0g／L）Fg、Fb和FDP干预24h后，分别检测该共培养体系中人脐静脉内皮细胞组织型纤溶酶原激活物和纤溶酶原激活物抑制剂mRNA水平（RT-PCR法）以及培养上清中组织型纤溶酶原激活物和纤溶酶原激活物抑制剂抗原含量（ELISA法）与活性（发色底物法）的变化情况。结果Fg对组织型纤溶酶原激活物的表达没有显著影响，较高浓度的Fg（3．0～4．5g／L）可明显促进纤溶酶原激活物抑制剂mRNA表达、抗原含量及活性升高，但过高浓度的Fg（6．0g／L）却抑制纤溶酶原激活物抑制剂的表达。3．0-4．5g／L的Fb对组织型纤溶酶原激活物mRNA和抗原含量都起上调作用，同时显著下调组织型纤溶酶原激活物活性。较高浓度的Fb（1．5-4．5g／L）则可明显上调纤溶酶原激活物抑制剂的表达，且在mRNA、蛋白和活性水平趋势基本一致。3．0-6．0g／L的FDP均可明显下调组织型纤溶酶原激活物mRNA、蛋白和活性水平，1．5-6．0mg／ml的FDP均可促进纤溶酶原激活物抑制剂的高表达。结论Fg、Fb和FDP可以通过影响组织型纤溶酶原激活物和纤溶酶原激活物抑制剂的表达，引起纤溶活性降低，参与动脉粥样硬化的发展进程。     

ACE inhibition versus angiotensin type 1 receptor antagonism: differential effects on PAI-1 over time

ACE inhibition reduces plasminogen activator inhibitor-1 (PAI-1), a risk factor for myocardial infarction, whereas the effect of angiotensin receptor antagonism on PAI-1 is uncertain. The present study compares the time course of effects of ACE inhibition and angiotensin type 1 (AT1) receptor antagonism on morning plasma PAI-1 antigen. Blood pressure and endocrine, metabolic, and fibrinolytic variables were measured in 20 insulin-resistant (defined by fasting glucose >8.3 mmol/L, body mass index >28 kg/m2, or fasting serum triglyceride > or =2.8 mmol/L) hypertensive subjects (mean age, 47.9+/-2.1 years) (1) before and after 1 week of hydrochlorothiazide 12.5 mg/d, and (2) before and 1, 3, 4, and 6 weeks after addition of ramipril (escalated to 10 mg/d) or losartan (escalated to 100 mg/d). Hydrochlorothiazide decreased systolic (P=0.011) and diastolic (P=0.019) pressure. Ramipril (from 133.6+/-5.1/94.5+/-2.4 to 127.0+/-3.1/91.4+/-3.3 mm Hg) or losartan (from 137.0+/-3.9/93.1+/-2.9 to 123.7+/-2.6/86.4+/-2.1 mm Hg) further reduced systolic (P=0.009) and diastolic (P=0.037) pressure. The pressure effects of the 2 drugs were similar. Hydrochlorothiazide increased plasma PAI-1 (P=0.013) but not tissue-type plasminogen activator (tPA) (P=0.431) antigen. Addition of either ramipril or losartan significantly decreased plasma PAI-1 antigen (P=0.046). However, the effect of losartan on PAI-1 antigen was not sustained throughout the 6-week treatment period, such that there was a significant drugxtime interaction (P=0.043). tPA antigen decreased during either ramipril or losartan (P=0.032), but tPA activity decreased only during losartan (P=0.018). Short-term interruption of the renin-angiotensin-aldosterone system by either ACE inhibition or AT1 receptor antagonism decreases PAI-1 antigen, but the duration of this effect is greater for ACE inhibition than for AT1 receptor antagonism.     

Is thyroid hormone suppression therapy prothrombotic?

The purpose of this study was to determine whether chronic thyroid hormone suppression therapy (THST) is prothrombotic.We obtained blood samples from 14 thyroid cancer patients while on THST and after they had become hypothyroid for radioiodine whole-body scanning and therapy. Prothrombin fragment 1 + 2, fibrinogen, factor VIII, antithrombin, tissue plasminogen activator antigen (tPA), plasminogen activator inhibitor 1 (PAI-1), PAI-1/tPA, and C-reactive protein were significantly (P < 0.05) higher in the hyper- than in the hypothyroid state, whereas protein C and plasmin-antiplasmin complexes were significantly lower during the hyperthyroid period. When the 10 female patients were hyperthyroid, their levels of prothrombin fragment 1 + 2, fibrinogen, protein S, antithrombin, tPA, PAI-1, and PAI-1/tPA were significantly higher (P 相似文献   

Protection by α2-macroglobulin of tissue plasminogen activator against inhibition by plasminogen activator inhibitor-1

Tissue plasminogen activator (tPA) is widely used in the treatment of acute myocardial infarction (MI). However, its thrombolytic efficacy does not correlate with the dose administered. The interactions between tPA, α2-macroglobulin (α2-M), and plasminogen activator inhibitor-1 (PAI-1) were investigated both in vitro and in patients undergoing tPA therapy for MI in an attempt to identify variables that might affect the clinical efficacy of tPA.
Purified α2-M (5.4 mg/ml) protected 16.0% or 22.4% of tPA (12.5 IU/ml) activity from inhibition by PAI-1 at 4 or 8 IU/ml in vitro . Of nine patients treated with 5–20 mega IU of tPA for MI, the plasma activity of tPA remained increased for 15–30 min after the cessation of infusion in eight; the patient who failed to exhibit a persistent increase in tPA activity had a low plasma concentration of α2-M. Total tPA activity, derived from the area under the activity-versus-time curve (AUC), showed a significant inverse correlation with the ratio of the plasma PAI-1 activity to the plasma α2-M concentration. Total tPA activity did not correlate with plasma PAI-1 activity or plasma α2-M concentration alone. Results suggest that α2-M, by binding to tPA, protects the latter against inhibition by PAI-1.     

同型半胱氨酸对人脐静脉内皮细胞纤溶系统的影响

目的探讨同型半胱氨酸（homocysteine,Hcy）对血管内皮细胞纤溶系统影响。方法（1）将体外培养的人脐静脉血管内皮细胞（HUVEC）分为10个实验组（0、10、50、200、500μmol／L Hcy组及叶酸和上述各Hcy点共同培养组）,培养24h后,酶联免疫吸附实验法（ELISA）测定各组细胞上清液中纤溶酶原激活剂（plasminogen activator,tPA）及纤溶酶原激活物抑制剂1（plasminogen activator inhibitor1,PAI-1）抗原含量,逆转录聚合酶链反应分析（RT-PCR）法分析各组tPA及PAI-1的mRNA表达水平。（2）急性心肌梗死（AMI）患者53例及健康对照组48例,ELISA测定空腹血浆tPA及PAI-1含量,高效液相色谱法测定血浆Hcy水平。结果（1）500μmoL／L Hcy组PAI-1抗原及mRNA表达水平均明显增高（P〈0．05）。（2）以单纯培养基为对照组,生理浓度Hcy组内皮细胞tPA抗原合成及mRNA表达明显增高（P〈0．05）,而以10μmoL／L Hcy组为对照组时,500μmoL／L Hcy组tPA抗原合成及mRNA表达水平则明显减少（P〈0．05）。（3）500μmoL／L Hcy与叶酸共同培养组和单纯Hcy组相比,可以明显提高内皮细胞tPA抗原的合成及mRNA表达,减少PAI-1抗原合成及mRNA表达（P〈0、05）。（4）AMI组Hcy、tPA及PAI-1均明显高于健康对照组（P〈0．05）。结论在体外细胞时,超生理浓度Hcy可以通过下调tPA、上调PAI-1的mRNA表达,减少内皮细胞tPA抗原的分泌及增加PAI-1抗原的合成,可能降低纤溶系统的活性。叶酸则可以减少Hcy引起内皮细胞纤溶系统的损害,起到保护作用。Hcy是AMI的一个独立危险因素。     

Increased expression of plasminogen activator and plasminogen activator inhibitor during liver fibrogenesis of rats: role of stellate cells.

BACKGROUND/AIMS: Plasminogen activators and plasminogen activator inhibitors are important regulators of the balance between the proteolytic and antiproteolytic activities that determine extracellular matrix turnover. We examined the expression of plasminogen activator-plasmin system components in experimental liver fibrosis of rats. METHODS: Liver fibrosis was produced in rats by injecting carbon tetrachloride for 6 to 12 weeks. Gene expression for plasminogen activator inhibitor-1 (PAI-1), urokinase and tissue plasminogen activators (uPA and tPA), urokinase plasminogen activator receptor (uPAR), and transforming growth factor-beta1 (TGF-beta1) was examined by Northern analysis. Western analysis was performed to detect protein expression of PAI-1, uPA and uPAR. An immunohistochemical study was performed to detect the localization of PAI-1. Additionally, primary cultured liver cells were examined by Northern and Western analyses for this protein with or without prior incubation with TGF-beta1. RESULTS: At 6 weeks, when fibrosis had occurred, uPA and uPAR mRNAs had increased 2.8-fold and 1.8-fold, respectively; PAI-1 and tPA mRNA levels were unchanged. At the cirrhotic stage (9 to 12 weeks), mRNA levels for PAI-1, uPA, uPAR and tPA were all increased. Western analysis also showed increased uPA and uPAR expressions in fibrotic liver, and increased PAI-1, uPA and uPAR expressions in cirrhotic liver. PAI-1 protein was also demonstrated immunohistochemically along sinusoids, vessels, and bile duct cells of normal and fibrotic liver. In liver cell cultures, Kupffer cells, hepatocytes, and especially stellate cells, expressed PAI-1. Expression was enhanced in stellate cells cultured from fibrotic or cirrhotic liver or stimulated in vitro with TGF-beta1. CONCLUSION: Though increased uPA and uPAR may act on matrix degradation in fibrotic liver, increased PAI-1 together with uPA, uPAR and tPA are associated with overall inhibition of matrix degradation in cirrhotic liver. Hepatic stellate cells are an important source of PAI-1 during liver fibrosis.     

氯沙坦和阿替洛尔对高血压患者纤溶系统及血浆血管性血友病因子的作用比较

目的比较血管紧张素受体拮抗剂(ARB)氯沙坦和β受体阻滞剂阿替洛尔对原发性高血压患者纤溶系统及血浆血管性血友病因子(vWF)的影响。方法轻中度原发性高血压患者60例随机分成氯沙坦组和阿替洛尔组(每组30例),分别给予氯沙坦50mg/(次.d)或阿替洛尔50mg/(次.d),共治疗8周。每4周随访1次,4周时血压如不达标(BP<140/90mmHg)则加用双氢克尿噻12.5mg/(次.d)。治疗前后行血浆组织型纤溶酶原激活物(tPA)及纤溶酶原激活物抑制剂1(PAI-1)检测,并计算PAI-1/tPA作为纤溶参数,同时测定血浆vWF的含量。结果两组的基线血压等一般情况具有可比性。治疗4周及8周时两组血压均较治疗前显著下降,组间比较无差异。同治疗前相比,氯沙坦组治疗8周时血浆PAI-1和vWF水平下降(P值分别<0.05及<0.01),PAI-1/tPA也有显著下降(P<0.05),而tPA则无显著变化(P>0.05);阿替洛尔组治疗8周时血浆PAI-1和vWF水平及PAI-1/tPA均无显著变化,而tPA则有所上升(P<0.05)。治疗后血浆vWF两组间比较,差异有非常显著意义。结论氯沙坦治疗能改善原发性高血压患者的纤溶系统并降低血浆vWF,而阿替洛尔则未见有此作用。     

Tissue plasminogen activator,plasminogen activator inhibitor-1 and von willebrand factor in rheumatoid arthritis

Summary Tissue plasminogen activator (tPA), plasminogen activator inhibitor-1 (PAI-1) and von Willebrand factor (vWF), all of endothelial origin and active in the haemostasis, were analysed in 74 patients with rheumatoid arthritis. The concentrations were related to extra-articular disease and to the incidence of thromboembolic events (TE) registered in a 2-year follow-up period. Patients with extra-articular disease had a significant increase in PAI-1 activity and reduced tPA release in the venous occlusion test. von Willebrand factor, PAI-1 and also haptoglobin and triglycerides were significantly increased in the group of patients who later suffered from TE. In a multiple regression model, in which cholesterol, triglycerides and lipoprotein (a) showed significant association with TE, vWF had the strongest additive explanatory value. No distinct acute phase pattern of PAI-1 was found in any patient subgroup.     

Effect of PAI-1 levels on the molar concentrations of active tissue plasminogen activator (t-PA) and t-PA/PAI-1 complex in plasma

We determined the in vivo molar concentrations of active tissue plasminogen activator (t-PA), active plasminogen activator inhibitor type 1 (PAI-1), and t-PA/PAI-1 complex. t-PA activity was measured in plasma stabilized by immediate acidification. PAI-1 activity and t- PA/PAI-1 complex antigen were measured in citrated plasma; these measurements were corrected for the loss in PAI-1 activity and increase in complex that occurs in unacidified plasma samples due to the continued reaction between t-PA and PAI-1 after the sample was drawn. To convert t-PA and PAI-1 activity measurements into molar concentrations we determined the specific molar activity of t-PA and PAI-1 in vivo: 4.48 x 10(13) IU/mol. Of 72 subjects studied, 13 had less than 150 pmol/L active PAI-1; in these individuals 33% +/- 21% of their t-PA was active and the molar ratio of active t-PA to active PAI- 1 was 0.20 +/- 0.13. In the 11 subjects with greater than 500 pmol/L active PAI-1, 1.5% = 1.1% of the t-PA was active and the molar ratio of active t-PA to active PAI-1 was 0.0043 +/- 0.0036. Overall, the fraction of active t-PA declined exponentially as a function of the active PAI-1 concentration. During the day, the percentage of total t- PA that was active increased from 12% at 8:00 AM to 31% at 8:00 PM, while the molar ratio of active t-PA to active PAI-1 increased from 0.05 to 0.22 from morning to evening (n = 12).     

In vitro and in vivo effects of tPA and PAI-1 on blood vessel tone

Tissue type plasminogen activator (tPA) is a key enzyme in the fibrinolytic cascade. In this paper we report that tPA contains 2 independent epitopes that exert opposite effects on blood vessel tone. Low concentrations of tPA (1 nM) inhibit the phenylephrine (PE)-induced contraction of isolated aorta rings. In contrast, higher concentrations (20 nM) stimulate the contractile effect of PE. The 2 putative vasoactive epitopes of tPA are regulated by the plasminogen activator inhibitor-1 (PAI-1) and by a PAI-1-derived hexapeptide that binds tPA. TNK-tPA, a tPA variant in which the PAI-1 docking site has been mutated, stimulates PE-induced vasoconstriction at all concentrations used. The stimulatory, but not the inhibitory, effect of tPA on the contraction of isolated aorta rings was abolished by anti-low-density lipoprotein receptor-related protein/alpha(2)-macroglobulin receptor (LRP) antibodies. Administering tPA or TNK-tPA to rats regulates blood pressure and cerebral vascular resistance in a dose-dependent mode. In other in vivo experiments we found that the vasopressor effect of PE is more pronounced in tPA knockout than in wild-type mice. Our findings draw attention to a novel role of tPA and PAI-1 in the regulation of blood vessel tone that may affect the course of ischemic diseases.     

Transcriptional profiling after bile duct ligation identifies PAI-1 as a contributor to cholestatic injury in mice

Extrahepatic cholestasis leads to complex injury and repair processes that result in bile infarct formation, neutrophil infiltration, cholangiocyte and hepatocyte proliferation, extracellular matrix remodeling, and fibrosis. To identify early molecular mechanisms of injury and repair after bile duct obstruction, microarray analysis was performed on liver tissue 24 hours after bile duct ligation (BDL) or sham surgery. The most upregulated gene identified encodes plasminogen activator inhibitor 1 (PAI-1, Serpine 1), a protease inhibitor that blocks urokinase plasminogen activator (uPA) and tissue-type plasminogen activator (tPA) activity. Because PAI-1, uPA, and tPA influence growth factor and cytokine processing as well as extracellular matrix remodeling, we evaluated the role of PAI-1 in cholestatic liver injury by comparing the injury and repair processes in wild-type (WT) and PAI-1-deficient (PAI-1-/-) mice after BDL. PAI-1-/- mice had fewer and smaller bile infarcts, less neutrophil infiltration, and higher levels of cholangiocyte and hepatocyte proliferation than WT animals after BDL. Furthermore, PAI-1-/- mice had higher levels of tPA activation and mature hepatocyte growth factor (HGF) after BDL than WT mice, suggesting that PAI-1 effects on HGF activation critically influence cholestatic liver injury. This was further supported by elevated levels of c-Met and Akt phosphorylation in PAI-1-/- mice after BDL. In conclusion, PAI-1 deficiency reduces liver injury after BDL in mice. These data suggest that inhibiting PAI-1 might attenuate liver injury in cholestatic liver diseases.     

Increased PAI-1 and tPA antigen levels are reduced with metformin therapy in HIV-infected patients with fat redistribution and insulin resistance

Cardiovascular disease (CVD) risk associated with fat redistribution seen among HIV-infected individuals remains unknown, but may be increased due to hyperlipidemia, hyperinsulinemia, increased visceral adiposity, and a prothrombotic state associated with these metabolic abnormalities. In this study we characterized plasminogen activator inhibitor-1 (PAI-1) and tissue-type plasminogen activator (tPA) antigen levels, markers of fibrinolysis and increased CVD risk, in HIV lipodystrophic patients compared to controls. Furthermore, we investigated the effect of treatment with metformin on PAI-1 and tPA antigen levels in patients with HIV-associated fat redistribution. Eighty-six patients (age 43 +/- 1 yr, BMI 26.1 +/- 0.5 kg/m(2)) with HIV and fat redistribution were compared to 258 age- and BMI-matched subjects from the Framingham Offspring study. In addition, 25 HIV-infected patients with fat redistribution and fasting insulin >15 microU/mL [104 pmol/L] or impaired glucose tolerance, but without diabetes mellitus were enrolled in a placebo-controlled treatment study of metformin 500 mg twice daily. PAI-1 and tPA antigen levels were significantly increased in patients with HIV related fat redistribution compared to Framingham control subjects (46.1 +/- 4 vs 18.9 +/- 0.9 microg/L PAI-1, 16.6 +/- 0.8 vs. 8.0 +/- 0.3 microg/L tPA, P = 0.0001). Among patients with HIV infection, a multivariate regression analysis including age, sex, waist-to-hip ratio, BMI, smoking status, protease inhibitor use and insulin area under the curve (AUC), found gender and insulin AUC were significant predictors of tPA antigen. Twelve weeks of metformin treatment resulted in decreased tPA antigen levels (-1.9 +/- 1.4 vs +1.4 +/- 1.0 microg/L in the placebo-treated group P = 0.02). Similarly, metformin resulted in improvement in PAI-1 levels (-8.7 +/- 2.3 vs +1.7 +/- 2.9 microg/L, P = 0.03). Change in insulin AUC correlated significantly with change in tPA antigen (r = 0.43, P = 0.03). PAI-1 and tPA antigen, markers of impaired fibrinolysis and increased CVD risk, are increased in association with hyperinsulinemia in patients with HIV and fat redistribution. Metformin reduces PAI-1 and tPA antigen concentrations in these patients and may ultimately improve associated CVD risk.     

Stimulation of plasminogen activator and inhibitor in the lymphatic endothelium

Chromogenic assays, immunoblotting, and Northern blot hybridization methods were employed to assess the effects of various agonists on the production of tissue plasminogen activator (t-PA) and plasminogen activator inhibitor type 1 (PAI-1) by the lymphatic endothelium (LEC). Fibrin autography showed that plasminogen-dependent fibrinolytic activity occurred at M(r) of 110 kDa, which represents a complex of tPA with PAI-1, and 65- and 55-kDa bands corresponding to tPA and uPA, respectively. The fractionation of lymph collected from ovine lymphatic vessels also produced a prominent lytic band of approximately 110 kDa, suggesting the formation of PA/PAI complexes in lymph. The stimulation of various agonists produced large-scale increases in tPA mRNA, as shown by Northern blot hybridization analyses. The effects of ECGF, histamine, and LPS on the presence of tPA and on enhancing the levels of mRNA reached maximum activity at 4 h and declined to levels below that of controls by 8 h. However, phorbol-treated cells exhibited reduced levels of tPA mRNA at 4 h, but was significantly increased by 8 h. A large-scale increase in PAI-1 mRNA steady-state levels was also stimulated by the agonists used in these studies. Both the 3.4- and 2.4-kb species of PAI-1 mRNA were increased. These observations demonstrated that tPA and PAI-1 are produced and secreted by LEC monolayer cultures and are also present in lymph.     

持续气道正压通气对OSAHS患者血管内皮细胞及纤溶系统的影响

为探讨经鼻持续气道正压通气（nCPAP)治疗前后阻塞性睡眠呼吸暂停低通气综合征（OSAHS）患者血管内皮细胞及纤溶系统的变化及临床意义，选择年龄，性别，体重指数（BMI）无明显差异的OSAHS患者38例和健康者对照组32例，用多导睡眠呼吸监测仪进行监测，以凝固法测定纤维蛋白原（Fg），发色底物法测组织纤溶酶原激活物活性（tPA：A）、纤溶酶原激活物抑制物－1活性（PAI－1：A），酶联免疫法测vonWillebrand因子（vWF)、组织纤溶酶原激活物抗原（tPA:Ag）、纤溶酶原含量（PLg:Ag)和纤溶酶原激活物抑制物－1含量（PAI－1：Ag）。结果OSAHS组与对照组比较，vWF,Fg,tPA:Ag、PAI－1：A明显升高（P分别＜0．01，0．001，0．001，0．01），PLg:Ag、tPA:A、tPA:Ag、最低血氧饱和度（SaO2low)明显降低（P分别＜0．01，0．001，0．001，0．01).nCPAP治疗后与治疗前比较，vWF,Fg,PAI-1:Ag,PAI-1:A明显降低（P分别＜0．05，0．01，0．01，0．01），PLg:Ag,tPA:A,tPA:Ag，最低SaO2明显升高（P分别＜0．05，0．001，0．001，0．01）。提示OSAHS患者血管内皮细胞损伤，凝血功能增强，纤溶系统功能减弱;nCPAP治疗能部分纠正各指标的异常。