AIMTo explore the effects of cholesterol rich diet on the activities of blood coagulative and fibrinolytic systems in male rabbits.

METHODS14 male New Zealand white rabbits were randomized to cholesterol rich diet(CRD) group and common diet (control) group. Rabbits in CRD group were fed with 1% cholesterol embedded diet and those in the control group were fed with common diet. Levels of blood TG, TC, LDL, HDL, Lp(a), apoA1, apoB, FIB, D-dimers and FDP, PT and APTT, activity of ADP, AT-III, PLG and alpha2-PI were tested in all rabbits before given cholesterol rich diet and after 12 weeks' feeding with different kinds of diet.

RESULTSLevels of blood TG, TC, LDL, HDL, Lp(a), apoA1, apoB, FIB, D-dimers in CRD group were all elevated significantly compared with those in the control group and the baseline levels. PT and APTT were shortened, ADP, PLG and alpha2-PI activity were increased in CRD group.

CONCLUSIONCholesterol rich diet not only is the direct cause of hyperlipidemia but also can increase the coagulative activity and inhibit the fibrinolytic activity and promoting the evolution of arteriosclerosis.

Animals ; Cholesterol ; blood ; Cholesterol, Dietary ; pharmacology ; Fibrinolysis ; drug effects ; Hyperlipidemias ; blood ; Lipoproteins, HDL ; blood ; Male ; Partial Thromboplastin Time ; Rabbits

Intravitreal fibrin clots were produced by intravitreal injection of 0.2 ml of autologous plasma in 62 rabbit eyes. The intravitreal injection of 0.25 micrograms or more of tissue plasminogen activator(tPA) resulted in a total clearing of intravitreal fibrin within one day in all treated eyes. This was significantly faster than in the control eyes, in which complete clearing was not seen until 8 days later. This represents the plateau on the dose-response curve in doses ranging from 0.25 to 200 micrograms. With light microscopy and transmission electron microscopy, retinal toxicity was demonstrated in eyes enucleated seven days after injection of 25 micrograms or more of tPA. This study demonstrates that tPA was effective and safe at 12.5 micrograms or less in clearing intravitreal fibrin in an experimental model. These results suggest that low dosages of tPA, probably of 3 micrograms or less, may be useful in the treatment of severe postvitrectomy fibrin formation seen clinically.
Animals ; Disease Models, Animal ; Dose-Response Relationship, Drug ; Fibrinolysis/*drug effects ; Rabbits ; Retina/drug effects/pathology ; Tissue Plasminogen Activator/*toxicity ; *Vitreous Body

OBJECTIVETo study the protective impact of tea polyphenols (TP) on the injury of fibrinolytic functions induced by high-methionine dietary in rats.

METHODS50 male Wistar rats were divided by stratified based on body weight into 5 groups with 10 in each group: namely control group, model group, low-dose TP group, medium-dose TP group and high-dose TP group. The rats in model group and TP groups were fed with 3% methionine dietary, control group rats with routine diet. In addition, rats in low-dose, medium-dose and high-dose TP groups were treated with TP at 50, 100 and 200 mg/kg dosage respectively by gavages every day, control group and model group rats were given with same amount distilled water. The animals were sacrificed after 8 weeks. The levels of tissue-type plasminogen activator (t-PA) and type-1 plasminogen activator inhibitor (PAI-1) in plasma were determined by ELISA assays, mRNA levels of t-PA and PAI-1 in aortic arch were detected by RT-PCR, t-PA and PAI-1 expression in aortic arch were detected by immunohistochemistry strept-avidin-biotin complex (SABC).

RESULTSAfter experiment, the t-PA expression of aortic arch in control group, model group, low-dose TP group, medium-dose TP group and high-dose TP group were 133.03 ± 10.14, 95.46 ± 11.08, 111.97 ± 11.91, 130.23 ± 10.80, 139.39 ± 9.41 (F = 14.15, P < 0.01), respectively, and the PAI-1 expression were 90.91 ± 8.67, 166.76 ± 12.18, 139.63 ± 12.71, 134.66 ± 13.19, 109.49 ± 10.82 (F = 31.44, P < 0.01). The t-PA concentration of plasma were (10.69 ± 1.26), (6.13 ± 0.92), (8.56 ± 1.19), (9.69 ± 0.92), (11.97 ± 1.08) ng/ml, respectively (F = 41.98, P < 0.01), and the PAI-1 concentration of plasma were (6.31 ± 0.81), (16.98 ± 1.27), (11.39 ± 0.82), (8.46 ± 0.67), (8.08 ± 0.91) ng/ml, respectively (F = 207.74, P < 0.01). The mRNA levels of t-PA in aortic arch were 1.12 ± 0.02, 0.75 ± 0.14, 1.01 ± 0.09, 0.95 ± 0.08, 1.05 ± 0.13 (F = 5.77, P < 0.05), and the mRNA levels of PAI-1 in aortic arch were 1.25 ± 0.11, 1.74 ± 0.06, 1.23 ± 0.05, 1.09 ± 0.14, 1.23 ± 0.04 (F = 23.56, P < 0.01).

CONCLUSIONThe results indicate that TP seems to have regulatory function on transcription and protein levels of t-PA and PAI-1, in addition to maintaining the balance between PAI-1 and t-PA and healing the injury of fibrinolytic functions in rats induced by high-methionine dietary.

Animals ; Diet ; Fibrinolysis ; drug effects ; Male ; Methionine ; adverse effects ; Plasminogen Activator Inhibitor 1 ; blood ; Polyphenols ; pharmacology ; Rats ; Rats, Wistar ; Tea ; chemistry ; Tissue Plasminogen Activator ; blood

The aim was to investigate the proteolytic activity of plasmin and its long-term complications. Plasmin was injected into the vitreous cavity of rabbits' eyes. Slit lamp biomicroscopy and electroretinography were performed. Rabbits were serially sacrificed at four months, and globes fixated and prepared for light and transmission electron microscopy. In both the plasmin-injected and control eyes, electroretinography showed a transient decrease in the amplitude, but this recovered to the baseline level in a week. Under the light microscope, the plasmin-treated eyes had a smooth retinal surface, implying separation of the vitreous cortex from the retina. In the control eyes, the collagen fibers remained on the retinal surface. By transmission electron microscopy, the plasmin-treated eyes showed a vitreous-free retinal surface, but no vitreoretinal separation was observed in the control eyes. Plasmin induces a cleavage between the vitreous and the internal limiting membrane, with no long-term complications, so may be a useful pharmacologic adjunct to vitrectomy.
Animals ; Electroretinography ; Fibrinolysis/*drug effects ; Fibrinolytic Agents/*pharmacology ; Injections ; Plasmin/*pharmacology ; Rabbits ; Research Support, Non-U.S. Gov't ; Retina/drug effects/physiology ; Vitreous Body/*drug effects ; Vitreous Detachment/*chemically induced/pathology

BACKGROUNDSepsis induced acute lung injury (ALI) as a common syndrome in clinical practice has a high mortality. Recombinant human activated protein C (APC) can significantly reduce the mortality of patients with severe sepsis. Several studies have implicated that APC may be protective in ALI.

METHODSTwenty-one rabbits were operatively prepared and randomly divided into sham, control, or APC groups (n = 7 in each group). After a tracheotomy had been performed, ALI was produced in the control and APC groups by infusion of Escherichia coli endotoxin 100 microg/kg per hour intravenously for 1 hour. The sham group received only the vehicle, infusion of 20 ml of 0.9% saline. The rabbits were studied under anesthesia for 6 hours and were ventilated with 40% oxygen. Bovine APC (25 microg x kg(-1) x h(-1)) was intravenously administered. The infusion was initiated half an hour post-injury and lasted for 4 hours. The animals were resuscitated with Ringer's lactate solution.

RESULTSIn comparison with nontreatment in the control group, the infusion of APC significantly reduced the increase of thrombomodulin level (TM; control group was (0.68 +/- 0.06) ng/ml, vs APC group of (0.62 +/- 0.07) ng/ml at 6 hours, P < 0.05), and significantly attenuated the fall in protein S (PS; control group was (2.32 +/- 0.03) microg/ml at 2 hours, (2.24 +/- 0.06) microg/ml at 4 hours and (2.21 +/- 0.09) microg/ml at 6 hours, vs APC group (2.46 +/- 0.04) microg/ml at 2 hours, (2.40 +/- 0.05) microg/ml at 4 hours and (2.39 +/- 0.07) microg/ml at 6 hours, P < 0.01). In addition, APC limited the increase in plasminogen activator inhibitor-1 (PAI-1) both in plasma (control group was (0.68 +/- 0.12) ng/ml at 1 hour, (0.84 +/- 0.06) ng/ml at 2 hours, (0.87 +/- 0.08) ng/ml at 4 hours and (0.91 +/- 0.05) ng/ml at 6 hours, vs APC group (0.42 +/- 0.16) ng/ml at 1 hour, (0.43 +/- 0.04) ng/ml at 2 hours, (0.45 +/- 0.09) ng/ml at 4 hours and (0.45 +/- 0.14) ng/ml at 6 hours, P < 0.01) and in bronchoalveolar lavage fluid (at 6 hours: sham, (1.05 +/- 0.05) ng/ml; control, (1.13 +/- 0.06) ng/ml; APC, (1.06 +/- 0.06) ng/ml; P < 0.05). However, APC failed to prevent the decrease in PaO(2)/FiO(2) ratio. APC-treated rabbits showed no significant difference in platelet count and antithrombin but exhibited less D-dimer production than did the controls. Moreover, APC limited the histopathological score of lung injury (2.6 +/- 0.8 in control, vs 1.4 +/- 0.6 in APC group, P < 0.01).

CONCLUSIONAnti-coagulation and pro-fibrinolysis activity may be two of the possible mechanisms by which activated protein C attenuated endotoxin-induced ALI.

Acute Lung Injury ; blood ; chemically induced ; Animals ; Antithrombin III ; metabolism ; Blood Coagulation ; drug effects ; Blood Pressure ; drug effects ; Endotoxins ; pharmacology ; Fibrinolysis ; drug effects ; Male ; Plasminogen Activator Inhibitor 1 ; blood ; Protein C ; pharmacology ; Protein S ; metabolism ; Rabbits ; Random Allocation ; Thrombomodulin ; blood

BACKGROUNDAcute lung injury/acute respiratory distress syndrome presents with not only local inflammation, but also pulmonary coagulopathy which is characterized by an alveolar procoagulant response, anticoagulant inhibition, fibrinolytic supression and fibrin deposition. We thus had hypothesized that if aerosolized unfractionated heparin was inhaled into alveolar spaces, it could block the procoagulant tendency, lessen depletion of coagulation factors, and even influence the inflammatory response. We also assessed the effects of different administration regimens of heparin.

METHODSMale Wistar rats were given inhaled heparin starting 30 minutes before (prophylactic heparin) or 2 hours after (therapeutic heparin) intravenous lipopolysaccharide (LPS) was administered at 6-hour intervals; control groups received inhaled normal saline with or without being exposed to LPS. Thrombin-antithrombin complexes, activated protein C, tissue type and urokinase type plasminogen activators (t-PA/u-PA), plasminogen activator inhibitor-1 (PAI-1), tumor necrosis factor-α, interleukin-6 in bronchoalveolar lavage, and lung tissue myeloperoxidase activity, and histology score were measured at three time-points. PAI-1/(t-PA + u-PA) was calculated based on the before-mentioned parameters. Statistical analysis was made using one-way analysis of variance (ANOVA) with post hoc test or Student's t test in the case of heterogeneity of variance.

RESULTSAn alveolar procoagulant reaction, depressed fibrinolysis, and inflammatory response occurred in endotoxemia-induced lung injury. Local prophylactic application of heparin attenuated coagulation and early inflammation, promoted fibrinolysis, and reduced the histology score. Therapeutic application of heparin had similar, but weaker effects.

CONCLUSIONSIntrapulmonary application of unfractionated heparin by inhalation might inhibit alveolar procoagulant reaction and the early inflammatory response, promote fibrinolysis, and alleviate pulmonary pathology in endotoxemia-induced lung injury rats. Administration of heparin before LPS challenge was more efficacious.

Acute Lung Injury ; blood ; drug therapy ; Administration, Inhalation ; Animals ; Blood Coagulation ; drug effects ; Endotoxemia ; complications ; Fibrinolysis ; drug effects ; Heparin ; administration & dosage ; Inflammation ; drug therapy ; Lung ; pathology ; Male ; Rats ; Rats, Wistar

OBJECTIVETo investigate the effects of propyl gallate (PrG) on the thrombus formation time and the coagulation/fibrinolysis system in an experimental carotid artery thrombosis model in rats.

METHODSFifty SD rats were randomly divided into 5 groups (10 animals/group): the normal group (normal saline 2 mL/kg), the model group (normal saline, 2 mL/kg), the heparin control group (1,250 IU/kg), the low dose PrG group (30 mg/kg), and the high dose PrG group (60 mg/kg). Thirty minutes after intravenous injection of saline or the corresponding drugs, a carotid artery thrombus was induced by continuous electric stimulation in all rats except for those in the normal group. The duration from the initiation of the electric stimulation to the sudden drop in carotid temperature was recorded as the thrombus formation time. Levels of plasma tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor-1 (PAI-1) were determined by ELISA.

RESULTSPrG (30 and 60 mg/kg) can prolong the thrombus formation time, but the effect was obviously weaker than that of heparin (P<0.05, P<0.01). Compared with the model group, PrG (30 and 60 mg/kg) elevated the plasma activity of t-PA (both P<0.05) and showed an increasing tendency in elevating the ratio of t-PA/PAI-1 (P>0.05), while it had no significant effect on the level of PAI-1.

CONCLUSIONPrG has a certain antithrombotic effect and can slightly regulate the imbalance of the t-PA /PAI-1 ratio.

Animals ; Blood Coagulation ; drug effects ; Carotid Artery Thrombosis ; drug therapy ; Female ; Fibrinolysis ; drug effects ; Male ; Plasminogen Activator Inhibitor 1 ; blood ; Propyl Gallate ; pharmacology ; therapeutic use ; Rats ; Rats, Sprague-Dawley ; Tissue Plasminogen Activator ; blood

OBJECTIVETo investigate the effect of cilazapril on endothelial cell function and fibrinolysis system in the canine atrial fibrillation (AF) models.

METHODSAll canines were divided into three groups: (1) Control group, without atrial pacing; (2) Atrial pacing group, in which atrial fibrillation was established by rapid atrial pacing at 400 bpm for 6 weeks; (3) Atrial pacing together with cilazapril group, in which cilazapril was given before and after atrial pacing. Nitric oxide (NO) of atrial endocardium was measured with NO-specific microelectrode. The expression of plasminogen activator inhibitor-1 (PAI-1) and tissue-type plasminogen activator (tPA) protein in atrium was determined by Western Blot analysis and immunohistochemical staining. Plasma levels of von Willebrand Factor (vWF), PAI-1 and tPA were analyzed by enzyme-linked immunoadsorbent assay.

RESULTSNO production from atrial endocardium was significantly increased in atrial pacing together with cilazapril group than atrial pacing group [(42.6 +/- 9.9) nmol/L vs (23.4 +/- 5.8) nmol/L, P < 0.05], whereas the plasma levels of vWF were decreased [(75.4 +/- 12.8)% vs (125.9 +/- 20.6)%, P < 0.05]. Compared to controls, the expression of atrium tPA protein in atrial pacing together with cilazapril group was significantly upregulated (4052 +/- 857 vs 1936 +/- 421, P < 0.05) and PAI-1 protein was downregulated (2487 +/- 542 vs 3164 +/- 827, P < 0.05). Cilazapril also significantly increased tPA antigen and decreased PAI-1 antigen in plasma.

CONCLUSIONCilazapril can favorably improve endothelial function and resume the balance of fibrinolysis system in AF, which might be of beneficial to hypercoagulated state in AF.

Angiotensin-Converting Enzyme Inhibitors ; pharmacology ; Animals ; Atrial Fibrillation ; blood ; drug therapy ; physiopathology ; Cilazapril ; pharmacology ; Disease Models, Animal ; Dogs ; Endothelial Cells ; drug effects ; physiology ; Female ; Fibrinolysis ; drug effects ; Immunohistochemistry ; Male ; Plasminogen Activator Inhibitor 1 ; analysis ; Tissue Plasminogen Activator ; analysis

Angiotensin-Converting Enzyme Inhibitors ; pharmacology ; Animals ; Atrial Fibrillation ; blood ; drug therapy ; physiopathology ; Cilazapril ; pharmacology ; Dogs ; Echocardiography ; Endothelial Cells ; drug effects ; physiology ; Fibrinolysis ; drug effects ; Nitric Oxide ; biosynthesis ; Plasminogen Activator Inhibitor 1 ; analysis ; Tissue Plasminogen Activator ; analysis

BACKGROUNDCigarette smoking has an influence on both arterial-type and venous-type thrombosis. However, little is known about the direct effect of cigarette smoke extract (CSE) on fibrinolytic activity of human umbilical vein endothelial cells (HUVECs). Most recently, simvastatin has been marked in its effect on endothelial cells protection and anticoagulation. In this study, the effect of CSE on the expression of tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor-1 (PAI-1) in HUVECs was addressed. The role of simvastatin in CSE-induced fibrinolytic activity changes was investigated as well.

METHODSThe fourth to fifth generation of HUVECs were incubated respectively with 0, 5%, 10% and 20% CSE for 6 hours or exposed to 5% CSE for 0, 4, 6, 8, 12, 24 hours to determine the expression changes of t-PA and PAI-1 protein. Meanwhile, cells were also accordingly exposed either to 5% CSE alone or simvastatin pre-treated and 5% CSE for 24 hours to assess the role of simvastatin in CSE-induced t-PA and PAI-1 protein and mRNA expression in HUVECs. RT-PCR and ELISA techniques were used for detecting the t-PA or PAI-1 mRNA and protein.

RESULTSAfter 6-hour exposure to CSE, the expression levels of t-PA protein in 10% and 20% CSE-treated groups reduced significantly ((0.0365 +/- 0.0083) ng/ml, (0.0255 +/- 0.0087) ng/ml) when compared with that of control group ((0.0660 +/- 0.0120) ng/ml) (P < 0.05). In contrast, the levels of PAI-1 protein in 5%, 10% and 20% CSE-treated groups increased remarkably ((13.3225 +/- 0.5680) ng/ml, (14.2675 +/- 1.5380) ng/ml, (14.4292 +/- 1.6230) ng/ml) when compared with that of control group ((8.5193 +/- 0.7537) ng/ml) (P < 0.05). After stimulation with 5% CSE for 0, 4, 6, 8, 12, 24 hours, the levels of PAI-1 protein increased over time and reached the peak at 24 hours ((14.6400 +/- 1.0651) ng/ml), which was significantly higher than that of control group ((12.0656 +/- 0.6148) ng/ml) (P < 0.05). Additionally, CSE could up-regulate PAI-1 expression at both the mRNA and the protein levels. The levels of PAI-1 mRNA and protein increased significantly in 5% CSE-treated group ((8.8030 +/- 0.4745) ng/ml, (1.8155 +/- 0.0412) ng/ml) compared with those of control groups ((5.0588 +/- 0.2315) ng/ml, (1.3030 +/- 0.0647) ng/ml) (P < 0.01), and decreased after 2-hour simvastatin pre-treatment ((5.4875 +/- 0.3166) ng/ml, (1.3975 +/- 0.0297) ng/ml) (P < 0.01). No significant difference was found at the levels of t-PA protein and mRNA (P > 0.05).

CONCLUSIONSCSE inhibits the fibrinolytic activity of HUVECs in vitro. Simvastatin plays a protective role in CSE-induced fibrinolytic malfunction.

Cells, Cultured ; Endothelial Cells ; metabolism ; Fibrinolysis ; drug effects ; Humans ; Hydroxymethylglutaryl-CoA Reductase Inhibitors ; pharmacology ; Plasminogen Activator Inhibitor 1 ; analysis ; biosynthesis ; genetics ; Simvastatin ; pharmacology ; Smoke ; adverse effects ; Tissue Plasminogen Activator ; analysis ; biosynthesis ; genetics ; Tobacco ; adverse effects ; Umbilical Veins ; cytology