Effects of perindopril treatment on hemostatic function in patients with essential hypertension in relation to angiotensin converting enzyme (ACE) and plasminogen activator inhibitor-1 (PAI-1) gene polymorphisms

BACKGROUND AND AIM: An imbalance in the hemostatic system is a frequent finding in untreated essential hypertension (HT), and it has been shown that treatment with angiotensin converting entyme (ACE) inhibitors improves hemostatic function. In order to elucidate the role of genetic factors, we studied hemostasis in patients with untreated and treated HT and correlated the results with ACE I/D and plasminogen activator enhibitor-1 (PAI-1) 4G/5G gene polymorphisms. METHODS AND RESULTS: Forty-three males with HT (mean age 31.7 +/- 6.8 years) were compared with 34 age and gender-matched controls. All of the patients were treated with perindopril (4 mg/day) and, after one and six months of therapy, their levels of plasma fibrinogen (Fb), t-PA antigen, PAI-1 antigen, von Willebrand factor (vWF), ACE activity and blood pressure were measured. ACE and PAI-1 genotypes were identified by means of the polymerase chain reaction on DNA isolated from peripheral blood lymphocytes. Untreated patients had significantly higher levels of Fb, PAI-1 (p < 0.01) and t-PA (p < 0.05) regardless of their ACE or PAI-1 genotypes. Perindopril reduced blood pressure regardless of ACE or PAI-1 genotype (p < 0.001). ACE II homozygotes showed the greatest decrease in ACE activity (p < 0.01) and a significant reduction in Fb levels (p < 0.05) after just one month of treatment. Analysis of the group as a whole revealed an increase in t-PA antigen levels after six months of treatment, regardless of ACE or PAI-1 genotype (p < 0.01). CONCLUSIONS: Our results show that essential hypertension predisposes to the procoagulant state characterized by hyperfibrinogenemia and hypofibrinolysis. Perindopril reduced fibrinogen levels in ACE II homozygotes due to its more potent inhibitory action on the renin-angiotensin system in such patients. It improved fibrinolysis by increasing t-PA levels regardless of ACE and PAI-1 genotype.     

The impact of angiotensin II receptor blockade and the DASH diet on markers of endogenous fibrinolysis

Hypertension is associated with impaired fibrinolysis. Both angiotensin receptor blockers (ARB) and the DASH (Dietary Approaches to Stop Hypertension) diet effectively lower blood pressure in hypertensive patients. Some evidence suggests that treatment with ARBs could increase fibrinolysis, however, data is conflicting. The impact of the DASH diet on fibrinolytic parameters is not known. Fifty-five hypertensive participants (35 African-American, 20 white) were randomly assigned to receive 8 weeks of either a control diet or the DASH diet. The diets did not differ in sodium content (approximately 3 g/day). Within each diet, individuals were randomly assigned to receive losartan or placebo for 4 weeks in double-blind, cross-over fashion. Tissue plasminogen activator (t-PA) antigen, t-PA activity, plasminogen activator inhibitor-1 (PAI-1) activity and plasma renin activity (PRA) were measured at the end of a 2-week run-in period on the control diet and after each treatment period. The DASH diet did not affect markers of fibrinolysis. Losartan significantly lowered t-PA antigen levels (-1.8 ng/mL, P = 0.045), but had no effect on t-PA or PAI-1 activities. This effect was more pronounced in whites (-4.1 ng/mL (P = 0.003)) compared with African-Americans (-0.3 ng/mL (P = 0.7), P-interaction = 0.03). Results were not materially affected by adjustment for basline values or changes in blood pressure. This study demonstrates that losartan reduces t-PA antigen levels in white, but not African-American hypertensive individuals. In contrast, the DASH diet had no significant effect on markers of fibrinolysis in whites or African-Americans.     

Differential effects of ACE-inhibition and angiotensin II antagonism on fibrinolysis and insulin sensitivity in hypertensive postmenopausal women

The aim of this study was to compare the effects of trandolapril and losartan on plasminogen activator inhibitor type 1 (PAI-1) levels and insulin sensitivity in hypertensive postmenopausal women. We studied 89 hypertensive (diastolic blood pressure >90 and <110 mm Hg) postmenopausal women, aged 51 to 60 years not taking any hormone replacement therapy. Diabetic, obese, and smoking patients were excluded. After a 4-week placebo period, they were randomized to receive 2 mg of oral trandolapril (n = 45) or 50 mg of oral losartan (n = 44) for 12 weeks according to a double-blind, parallel group design. At the end of the placebo and active treatment periods, blood pressure (BP) was measured, plasma samples were drawn to evaluate PAI-1 antigen levels, and insulin sensitivity was assessed. Both trandolapril and losartan reduced systolic BP (by a mean of 16.9 mm Hg and 15.2 mm Hg, respectively, P < .01 v placebo) and diastolic BP (by a mean of 13.1 mm Hg and 11.9 mm Hg, respectively, P < .01 v placebo) with no difference between the two treatments. The PAI-1 antigen levels were significantly decreased by trandolapril (from 36.9 ± 21 ng/dL to 27.2 ± 17 ng/dL, P < .05), but not by losartan (from 35.3 ± 22 ng/dL to 37.1 ± 23 ng/dL, P = not significant). Glucose infusion rate was significantly increased by trandolapril (from 6.67 ± 0.56 mg/min/kg to 7.9 ± 0.65 mg/min/kg, P < .05), but was not significantly modified by losartan (from 6.7 ± 0.47 mg/min/kg to 6.9 ± 0.50 mg/min/kg, P = not significant). In the trandolapril group the PAI-1 decrease correlated with glucose infusion rate increase (r = 0. 36, P = .045) These results provide evidence of different effects of angiotensin converting enzyme inhibitors and AT₁ antagonists on fibrinolysis and suggest that the PAI-1 decrease induced by angiotensin converting enzyme inhibitors is related to their action on insulin sensitivity and is not dependent on angiotensin II antagonism but rather on other mechanisms. It remains to be seen whether these findings apply to other patient populations than postmenopausal women.     

Angiotensin-converting enzyme inhibition but not angiotensin II type 1 receptor antagonism augments coronary release of tissue plasminogen activator in hypertensive patients

OBJECTIVES: We compared the effects of perindopril and losartan on endothelium-dependent coronary vasomotor and fibrinolytic function. BACKGROUND: The renin-angiotensin system regulates the vascular fibrinolytic balance. However, the effects of angiotensin-converting enzyme inhibitors and angiotensin II type 1 receptor antagonists on coronary fibrinolytic function have not been compared in hypertensive patients. METHODS: Forty-five patients with hypertension were randomly assigned to three groups: 16 patients were treated with perindopril (4 mg/day) for four weeks; 15 were treated with losartan (50 mg/day) for four weeks; and 14 were not treated with either perindopril or losartan (control group). Graded doses of bradykinin (BK) (0.2, 0.6, and 2.0 microg/min) were administered into the left coronary artery. Coronary blood flow (CBF) was evaluated by Doppler flow velocity measurement. RESULTS: Bradykinin induced dose-dependent increases in CBF in all groups. The increases in CBF induced by BK in the perindopril and losartan groups were significantly greater than those in the control group. Net coronary tissue-type plasminogen activator (t-PA) release was enhanced by BK in all groups, and the increase in the perindopril group was greater than that in the losartan and control groups. Bradykinin did not alter plasminogen activator inhibitor type 1 levels in any of the groups. CONCLUSIONS: Perindopril and losartan similarly augment BK-induced coronary vasodilation. Perindopril may have a greater potential to enhance the BK-induced coronary release of t-PA than losartan.     

Comparative effect of angiotensin-converting enzyme inhibition and angiotensin II type 1 receptor antagonism on plasma fibrinolytic balance in humans.

Angiotensin-converting enzyme (ACE) inhibition significantly decreases plasminogen activator inhibitor-1 (PAI-1) without altering tissue plasminogen activator (tPA) during activation of the renin-angiotensin-aldosterone system in humans. Because ACE inhibitors and angiotensin II type 1 (AT(1)) receptor antagonists differ in their effects on angiotensin II formation and bradykinin degradation, the present study compared the effect of equivalent hypotensive doses of an ACE inhibitor and AT(1) antagonist on fibrinolytic balance. Plasma PAI-1 antigen, tPA antigen, plasma renin activity, and aldosterone were measured in 25 normotensive subjects (19 white, 6 black; 14 men, 11 women; mean age 38.5+/-1.8 years; mean body mass index 25.3+/-0.7 kg/m(2)) during low salt intake alone (10 mmol Na/d), low salt intake + quinapril (40 mg PO bid), and low salt intake + losartan (50 mg PO bid). Compared with low salt alone (systolic blood pressure [BP] 118.8+/-2.2 mm Hg), both quinapril (106.3+/-2.5 mm Hg, P<0.001) and losartan (105.4+/-2. 8 mm Hg, P<0.001) reduced BP. No statistical difference was found between quinapril and losartan in their BP lowering effect. Losartan (P=0.009), but not quinapril, lowered heart rate. Both drugs significantly lowered aldosterone (P<0.001 versus low salt alone for each); however, this effect was significantly greater for quinapril than for losartan (P<0.001 for quinapril versus losartan). Treatment with quinapril, but not with losartan, was associated with a decrease in both PAI-1 antigen (P=0.03) and activity (P=0.018). PAI-1 activity was lower during treatment with quinapril than with losartan (P=0.015). The average PAI-1 antigen concentration was 13. 0+/-2.0 ng/mL during low salt alone, 10.5+/-1.6 ng/mL during quinapril treatment, and 12.3+/-2.1 ng/mL during losartan treatment. In contrast, plasma tPA antigen concentrations were reduced during treatment with losartan (P=0.03) but not with quinapril. This study provides the first evidence that ACE inhibitors and AT(1) antagonists differ in their effects on fibrinolytic balance under conditions of activation of the renin-angiotensin-aldosterone system. Further studies are needed to address the mechanism for the contrasting effects of these 2 classes of drugs on fibrinolysis and to define the clinical significance of these differences.     

In patients with deep-vein thrombosis elevated levels of factor VIII correlate only with von Willebrand factor but not other endothelial cell-derived coagulation and fibrinolysis proteins.

Several studies have shown that patients with venous thrombosis have elevated levels of factor VIII (FVIII) at an increased frequency. Most such patients also have high von Willebrand factor (vWF) levels. Since vWF is synthesized by the vascular endothelium, we hypothesized that elevated FVIII levels would also be associated with an increase of other endothelial cell-derived coagulation proteins suggesting perturbation of the endothelium. In 100 healthy individuals and 129 patients with venous thromboembolism, we have determined antigenic FVIII levels along with several endothelial proteins including vWF, soluble thrombomodulin (sTM), tissue-type plasminogen activator (t-PA), and plasminogen activator inhibitor 1 (PAI-1). Levels of FVIII, vWF, PAI-1 and t-PA were significantly increased in patients compared with the controls (FVIII, vWF, and PAI-1,P < 0.001; t-PA, P < 0.05). Levels of sTM, however, were higher in the controls than in the patients (P < 0.001). Whereas the FVIII levels correlated well with the vWF levels in the patients (correlation, 0.61; P < 0.001) and the controls (correlation, 0.70; P < 0.001), there was neither a relevant correlation between FVIII and sTM, PAI-1, and t-PA, nor between vWF and sTM, PAI-1, and t-PA in the patients and the controls. In conclusion, although levels of PAI-1 and t-PA can be found, on average, at increased levels in patients with thrombosis, FVIII levels correlate only with vWF but not other endothelial cell-derived coagulation and fibrinolysis proteins including sTM, PAI-1, and t-PA.     

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.     

Clinical significance of hemostatic markers and thrombomodulin in systemic lupus erythematosus: evidence for a prothrombotic state

Systemic lupus erythematosus (SLE) is a systemic autoimmune disorder with overwhelming thrombotic states. The precise pathogenetic mechanisms underlying the prethrombotic state in SLE is not fully understood, but interactions between the antiphospholipid antibodies and antigen targets on the coagulation components have been incriminated to play fundamental roles. To evaluate this issue, 34 women with antiphospholipid antibody negative SLE were investigated for molecular markers of blood coagulation and fibrinolytic activity: prothrombin fragment1+2 (PF1+2), thrombin-antithrombin complex (TAT), plasmin-alpha2-antiplasmin inhibitor complex (PAP), and tissue factor pathway inhibitor (TFPI). We also analysed plasma soluble thrombomodulin (sTM) levels. SLE disease activity was determined using the SLE Disease Activity Index (SLEDAI). Concentrations of TAT, PAP, PF1+2 and sTM were significantly elevated (P<0.0001, P=0.0002, P<0.0001, and P<0.0001, respectively), while TFPI antigen levels were found to be reduced (P<0.0001) in patients with SLE compared to the control group. In patients with active SLE, anti-ds DNA levels were correlated positively with plasma TAT (P<0.05), PF1+2 (P<0.05), and sTM (P<0.01) concentrations and negatively with plasma TFPI levels (P<0.05). SLEDAI scores were correlated positively with plasma TAT (P<0.01), PF1+2 (<0.01), and sTM (P<0.01) levels. This study illustrates that both a prethrombotic state and a compensatory fibrinolytic process secondary to subclinical intravascular coagulation might coexist in SLE with elevated sTM levels, indicating impaired endothelial functions.     

Fibrinolytic function in diuretic-induced volume depletion

Accumulating evidence suggests that the renin-angiotensin system (RAS) may participate in the regulation of fibrinolytic function. In clinical studies, however, angiotensin-converting enzyme (ACE) inhibitors and the angiotensin II receptor antagonist losartan have failed to consistently affect endogenous fibrinolysis. Because such an effect may depend on the degree of prestimulation of the RAS, we have studied parameters of fibrinolytic function in 15 healthy volunteer subjects during baseline (day 1) and after 10 days of treatment with 25 mg of hydrochlorothiazide (HCT)/day (day 11). On the last day of the study (day 12), a single oral dose of 50 mg of losartan was given to the volunteers in addition to HCT and fibrinolytic function was assessed at the peak effect of losartan (5 h later). Plasma renin activity (PRA) was significantly stimulated during diuretic treatment (1.35 ± 0.21 v 0.34 ± 0.06 ng mL⁻¹ · h⁻¹ [P < .001]) and further increased after losartan (6.39 ± 1.16 ng mL⁻¹ · h⁻¹ [P < .001]). No effects of either the diuretic or losartan could be observed on tissue-type plasminogen activator (t-PA) antigen concentration and activity. However, 10 days of treatment with HCT significantly increased plasminogen activator inhibitor-1 (PAI-1) antigen (26.8 ± 5.8 v 21.1 ± 3.4 ng/mL [p = .037]). In addition, PAI-1 activity was also tentatively raised by HCT treatment (5.48 ± 1.82 v 3.88 ± 0.79 IU/mL [P = .067]). In spite of the marked further rise in PRA after losartan, the stimulation of PAI-1 antigen and activity was blunted by losartan (24.4 ± 3.6 ng/mL and 4.55 ± 0.99 IU/mL, respectively). Our results demonstrate that volume depletion induced by HCT treatment is associated with a rise in PAI-1. Acute administration of losartan is capable of blunting this effect, suggesting that the angiotensin II type 1 receptor may participate in this effect of angiotensin II.     

Blood coagulation and fibrinolysis in patients with acromegaly: increased plasminogen activator inhibitor-1 (PAI-1), decreased tissue factor pathway inhibitor (TFPI), and an inverse correlation between growth hormone and TFPI

Objective Growth hormone/insulin-like growth factor-1(GH/IGF-1) hypersecretion may influence risk factors contributing to the increased cardiovascular morbidity and mortality associated with acromegaly However, so far little is known about the impact of GH/IGF-1 on coagulation and fibrinolysis in acromegalic patients as possible risk factors for cardiovascular disease (CVD). To our knowledge, plasma tissue factor pathway inhibitor (TFPI) and thrombin-activatable fibrinolysis inhibitor (TAFI) levels in these patients have not been investigated. Therefore, the main purpose of this study was to evaluate the markers of endogenous coagulation/fibrinolysis, including TFPI and TAFI, and to investigate the relationships between GH/IGF-1 and these hemostatic parameters and serum lipid profile in patients with acromegaly. Research Methods and Procedures A total of 22 patients with active acromegaly and 22 age-matched healthy controls were included in the study. Fibrinogen, factors V, VII, VIII, IX, and X activities, von-Willebrand factor (vWF), antithrombin III (AT III), protein C, protein S, tissue plasminogen activator (t-PA), tissue plasminogen activator inhibitor-1 (PAI-1), TFPI and TAFI, as well as common lipid variables, were measured. The relationships between serum GH/IGF-1 and these hemostatic parameters were evaluated. Results Compared with the control subjects, fibrinogen, AT III, t-PA, and PAI-1 were increased significantly in patients with acromegaly (P < 0.0001, P < 0.05, P < 0.01, and P < 0.0001, respectively), whereas protein S activity and TFPI levels were decreased significantly (P < 0.05 and P < 0.01, respectively). Plasma TAFI Ag levels did not significantly change in patients with acromegaly compared with the controls. In patients with acromegaly, serum GH levels were inversely correlated with TFPI and apo AI levels (r: −0.514, P: 0.029 and r: −0.602, P: 0.014, respectively). There was also a negative correlation between insulin-like growth factor −1 (IGF-1) and PAI-1 (r: −0.455, P:0.045). Discussion We found some important differences in the hemostatic parameters between the patients with acromegaly and healthy controls. Increased fibrinogen, t-PA, PAI-1 and decreased protein S and TFPI in acromegalic patients may represent a potential hypercoagulable and hypofibrinolytic state, which might augment the risk for atherosclerotic and atherothrombotic complications. Thus, disturbances of the hemostatic system and dyslipidemia may contribute to the excess mortality due to CVD seen in patients with acromegaly.     

Impaired fibrinolysis and insulin resistance in patients with hypertension

Plasma plasminogen activator inhibitor type 1 (PAI-1) and tissue plasminogen activator (tPA) antigens and activities were measured in 28 patients with hypertension and 12 normal controls. Steady state plasma glucose (SSPG) concentrations were also determined after an infusion of somatostatin, insulin and glucose. Patients with hypertension were further subdivided into two groups: insulin resistance (SSPG > 190 mg/dL, n = 14) and no insulin resistance (SSPG < 190 mg/dL, n = 14). As compared to normal controls, hypertensive patients, either with or without insulin resistance, had significant (P < .005) increases in PAI-1 activity (18.6 ± 1.3 ν 8.1 ± 0.8 IU/mL), PAI-1 antigen (31.1 ± 2.0 ν 12.7 ± 0.9 ng/mL) and tPA antigen (15.5 ± 0.9 ν 8.8 ± 0.9 ng/mL), and significant decrease in tPA activity (0.43 ± 0.05 ν 1.02 ± 0.16 IU/mL) than normotensive controls. Furthermore, hypertensive patients with insulin resistance had significantly higher PAI-1 activity (22.0 ± 2.2 ν 15.3 ± 0.8 IU/mL, P = .006) and tPA antigen (17.4 ± 1.2 ν 13.6 ± 1.3 ng/mL, P = .02) than did hypertensive patients without insulin resistance. However, PAI-1 antigen was insignificantly higher (34.1 ± 2.9 ν 28.1 ± 2.4 ng/mL, P = .06) and tPA activity insignificantly lower (0.42 ± 0.08 ν 0.43 ± 0.08 IU/mL, P = .45) in hypertensive patients with insulin resistance than in those without insulin resistance. In addition, PAI-1 activity and tPA antigen were significantly correlated with blood pressure, SSPG, triglyceride, HDL-cholesterol and integrated glucose response to an oral load of 75 g glucose. Thus, patients with hypertension have impaired fibrinolytic activity due to increased PAI-1 when compared to normotensive controls, and the magnitude of this fibrinolytic defect is greater in hypertensive patients who have insulin resistance. Insulin resistance with associated metabolic abnormalities may be one of the causes for impaired fibrinolysis in hypertension.     

Plasminogen activator inhibitor-1 (PAI-1) 4G/5G and angiotensin converting enzyme (ACE) I/D gene polymorphisms and fibrinolytic activity in patients with essential hypertension and dyslipidemia

Essential arterial hypertension often predisposes patients to prothrombotic state and increased risk of vascular and organ complications. Vital role in regulation of hemostatic processes is played by genetic factors, renin-angiotensin system and disorders of lipid metabolism. Prime genetic factors involved in the process are 4G/5G polymorphism of promoter region coding tissue plasminogen activator inhibitor-1 (PAI-1) and I/D polymorphism for angiotensin converting enzyme (ACE) gene. The aim of work was the evaluation of alterations within fibrinolysis system (estimation of t-PA and PAI-1 levels), fibrinogen concentration (Fb) and ACE activity with regard to co-existent dyslipidemia and features of left ventricle hypertrophy (LVH). Moreover the analysis of influence of 4G/5G PAI and I/D ACE gene polymorphism on intensification of aforementioned alterations among hypertensive patients was performed. Research was carried out in 170 subjects under 40 years old, in two study groups, HT-- hypertensive group--125 patients with previously untreated hypertension without clinical features of ischaemic heart disease and NT--45 normotensive, healthy subjects. HT group has been further divided into four subgroups: DLP (dyslipidemic, n = 51), NLP (normolipidemic n = 74), LVH+ (with features of left ventricle hypertrophy, n = 35), LVH (-) (without features of left ventricle hypertrophy, n = 90). In a whole HT group significantly higher levels of PAI-1, t-PA and Fb were noted in comparison to NT group, considerably more pronounced within DLP rather than NLP subgroups. Moreover, pronounced increase in ACE activity was recorded in DLP and LVH+ subgroups. It has been proved that 4G/4G homozygous subjects of 4G/5G PAI-1 gene polymorphism from HT group tend to present higher levels of PAI-1 and t-PA if contrasted to 4G/4G genotype of NT group, with more distinct effect within DLP subgroup. Carriers of D allele (genotypes I/D, D/D) of I/D ACE gene polymorphism from HT group characterise with significantly higher activity of ACE in contrast to I/I genotype of HT group, with particularly marked effect in DLP and LVH+ subgroups. Basing on above mentioned results it may be concluded that essential hypertension (especially if complicated with dyslipidemia) impairs fibrinolysis, what might be related to renin-angiotensin system activation in lipid metabolism disorders. Deletion alleles of 4G/5G polymorphism (4G allele) and I/D polymorphism (D allele) in patients with hypertension independently modify fibrinolysis towards prothrombotic state with more distinct effect in dyslipidemia. Increased activity of ACE in D allele carriers may predispose to left ventricle hypertrophy.     

血栓形成标志物与原发性高血压的关系

目的判断原发性高血压患者是否存在血栓前状态(pretbrombotic state,PTS),并探讨PTS在原发性高血压患者中的意义。方法运用酶联免疫吸附双抗体夹心法(ELISA)、酶联免疫吸附竞争法、发色底物法、凝固法等检测手段,检测了1 000例原发性高血压患者和100例健康成人的6-酮-前列腺素F1α(6-K-PGF1α)含量、血栓素B2(TXB2)含量、纤维蛋白原(Fib)含量、组织型纤溶酶原激活剂(t-PA)及纤溶酶原激活抑制物-1(PAI-1)的含量和活性及血液流变学等指标的变化进行分析与评价。结果与对照组比较,1~2级高血压组及3级高血压组患者血浆TXB2、Fib水平、PAI-1含量及活性、血黏度均显著升高(P<0.01);而6-K-PGF1α含量t、-PA含量及活性均显著下降(P<0.01)。结论高血压病患者存在PTS,PTS与高血压病患者的病情发展,血栓栓塞性疾病的发生密切相关。     

脑血栓形成病人血浆及脑脊液t-PA及其PAI-1含量的观察

目的：研究动脉粥样硬化性脑血栓形成病人血浆及脑脊液组织型纤溶酶原激活物（t-PA)及其抑制物（PAI-1）含量的变化及其临床意义。方法：采用双抗体夹心固相酶联免疫吸附法（ELISA）检测35例脑血栓形成病人血浆和其中31例病人脑脊液t-PA及PAI-1抗原含量，与35例正常对照组血浆和其中20例对照组脑脊液进行比较。结果；脑血栓形成组血浆t-PA含量高于对照组，PAI-1含量显著高于对照组；其脑脊液t-PA,PAI-1含量均显著高于对照组，脑脊液中t-PA,PAI-1的含量分别与血浆中t-PA,PAI-1的含量，分别与血浆中t-PA,PAI-1的含量呈正相关；脑血栓形成组病人神经功能缺损评分与血浆及脑脊液t-PA,PAI-1抗原含量呈正相关。结论：脑血栓形成病人纤溶活性明显下降，t-PA及PAI-1参与了脑血栓形成之病理过程；t-PA及PAI-1抗原含量是反映体内纤溶活性的两个重要指标；可用血浆或脑脊液t-PA,PAI-1的含量作为判断病情的参考指标之一。     

Effect of the angiotensin II receptor blocker candesartan on fibrinolysis in patients with mild hypertension

Aim:  Impaired fibrinolysis is frequently observed in patients with the metabolic syndrome. Aim of the study was to examine the short-term effect of angiotensin II receptor blockade on the fibrinolytic system.
Methods:  Seventy-four patients with mild hypertension were randomly assigned to a 7-day treatment period with either 16 mg candesartan cilexetil or placebo. Several variables of the fibrinolytic system such as plasminogen activator inhibitor-1 (PAI-1) antigen and activity, tissue plasminogen activator (t-PA) antigen and activity as well as circulating t-PA/PAI-1 complexes were determined.
Results:  At baseline, the body mass index but not blood pressure was positively associated with PAI-1 antigen (r = 0.314, p < 0.01) and PAI-1 activity (r = 0.425, p < 0.01) but negatively with t-PA activity (r = −0.187, p < 0.05). A 7-day treatment with 16 mg candesartan cilexetil resulted in a significant greater reduction of diastolic blood pressure (−10.3 ± 10.8 mmHg vs.−5.8 ± 8.5 mmHg, p = 0.03). However, there was no significant effect of candesartan on all parameters of the fibrinolytic system under investigation, i.e. circulating PAI-1 antigen, PAI-1 activity, t-PA antigen, t-PA activity and t-PA/PAI-1 complexes. Furthermore, candesartan did not affect the characteristic circadian pattern of the variables of the fibrinolytic system.
Conclusion:  We conclude that short-term blockade of the angiotensin II receptor subtype 1 with candesartan does not have an impact on fibrinolysis in patients with mild hypertension.     

高血压病患者血栓前状态的临床研究

目的通过观察高血压病患者血栓前状态分子标志物的变化,探讨其易并发血栓性疾病的机制,为临床早期诊治提供客观依据。方法对山东省血栓病防治工程技术研究中心与山东省交通医院2000-04~2004-05的1000例高血压病患者及100例健康对照者的血浆血栓前状态(PTS)分子标志物进行检测,包括:血管性血友病因子(vWF)、血小板α-颗粒膜蛋白-140(GMP-140)、11-去氢血栓烷B2(11-DH-TXB2)、纤维蛋白原(FIB)、抗凝血酶(AT);组织型纤溶酶原激活剂(t-PA)、纤溶酶原激活剂抑制物-1(PAI-1)的活性水平及血液流变学指标,并进行分析与评价。结果与对照组相比,高血压病患者的血浆vWF、GMP-140、11-DH-TXB2、FIB含量,PAI-1活性及血黏度均明显升高,而AT含量、t-PA活性均明显下降,差异极其显著(P<0·01)。随着血压升高,PTS标志物变化越显著(P<0·05)。结论高血压病患者存在PTS,PTS与其病情进展、血栓性疾病的发生密切相关。     

Neutral endopeptidase and angiotensin I converting enzyme insertion/deletion gene polymorphism in humans

Neutral endopeptidase (NEP) hydrolyses angiotensins (Ang) I and II and generates angiotensin-(1-7) [Ang-(1-7)]. In humans, the insertion/deletion (I/D) angiotensin-I converting enzyme (ACE) gene polymorphism determined plasma ACE levels by 40%. In rats, a similar polymorphism determines ACE levels which are inversely associated to NEP activity. The objective of this study is to evaluate the relationship between ACE expression and plasma NEP activity in normotensive subjects and in hypertensive patients. In total, 58 consecutive patients with hypertension, evaluated in our Hypertension Clinic, were compared according to their ACE I/D genotypes with 54 control subjects in terms of both plasma ACE activity and NEP activities. Plasma ACE activity was elevated 51 and 70% in both DD ACE groups (normotensives and hypertensives) compared with their respective ID and II ACE groups (P<0.001). A significant effect of the ACE polymorphism and of the hypertensive status on ACE activity was observed (P<0.001). In normotensive DD ACE subjects, NEP activity was 0.30+/-0.02 U/ml, whereas in the normotensive II ACE and in the normotensive ID ACE subjects NEP activity was increased 65 and 48%, respectively (P<0.001). In the hypertensive DD ACE patients, NEP activity was 0.47+/-0.03 U/mg. An effect of the I/D ACE genotypes on NEP activity (P<0.04) and an interaction effect between the I/D ACE genotype and the hypertensive status were also observed (P<0.001). These results are consistent with a normal and inverse relationship between the ACE polymorphism and NEP activity in normotensive humans (as is also observed in rats). This normal relationship is not observed in hypertensive patients.     

Behaviour of tissue plasminogen activator, plasminogen activator inhibitor 1 and their complex in various disease states.

Plasma levels of tissue plasminogen activator (t-PA) antigen, plasminogen activator inhibitor 1 (PAI-1) antigen and t-PA/PAI-1 complex were measured in plasmas from 18 healthy subjects and 75 patients with various diseases (28 patients with haematological malignancies, 20 with thrombotic diseases, five with infectious diseases, four with liver diseases, ten with bleeding disorders and eight miscellaneous conditions). In addition, we studied ten patients with bleeding disorders after DDAVP infusion and 18 healthy subjects after venous occlusion. Plasma levels of t-PA antigen, PAI-1 antigen and t-PA/PAI-1 complex were increased in the patients compared with the healthy subjects. t-PA/PAI-1 complex levels correlated well with t-PA antigen levels and molar concentrations of t-PA antigen were similar to those of the t-PA/PAI-1 complex. Venous occlusion induced an increase in both t-PA antigen and PAI-1 antigen and the molar concentration of the t-PA/PAI-1 complex was equivalent to that of t-PA antigen. Following DDAVP infusion, the levels of t-PA antigen and t-PA/PAI-1 complex increased but PAI-1 antigen levels decreased, and the increase of t-PA antigen was greater than that of t-PA/PAI-1 complex. These findings indicate that PAI-1 antigen exceeds t-PA antigen in healthy subjects and in patients with various diseases. We conclude that part of the t-PA/PAI-1 complex is rapidly cleared from the circulation and that free t-PA increases after DDAVP infusion.     

Acute effects of angiotensin II on fibrinolysis in healthy volunteers.

Recent studies have suggested that angiotensin II may inhibit fibrinolysis. In order to further test this hypothesis, we investigated the acute effects of angiotensin II (intravenous infusion of 10 ng/kg per min over 15-20 min) on fibrinolytic function in 18 healthy men. Time-controls (n=11) and control experiments with a placebo infusion (n = 13) were also performed. The activities of plasmin activator inhibitor-1 (PAI-1) and tissue-type plasminogen activator (t-PA), as well as t-PA antigen levels, were determined in plasma before, during and 60 min after the infusion of angiotensin II. Angiotensin II caused a clear-cut elevation in blood pressure; heart rate and plasma noradrenaline levels tended to decrease during the infusion but increased afterwards, indicating reflexogenic adjustments. Plasma t-PA activity and antigen levels increased by 81+/-11 and 14+/-3%, respectively, during angiotensin II infusion (both P < 0.001), whereas t-PA activity was unchanged and t-PA antigen decreased (P < 0.05) in placebo experiments. PAI-1 activity decreased similarly in time-controls and during angiotensin infusion (P < 0.001). Thus, short-term infusion of angiotensin II enhances fibrinolysis by elevating plasma t-PA. It is not clear whether this is a direct angiotensin-receptor-mediated effect or if it is related to the hemodynamic effects of the infusion.     

Fibrinolytic actions of intra-arterial angiotensin II and bradykinin in vivo in man

OBJECTIVES: Angiotensin II and bradykinin are potent endogenous vasoactive peptides which may play a role in the regulation of endogenous fibrinolysis and, thereby, contribute to the beneficial actions of ACE inhibitors. The aims of the study were to determine the acute effect of angiotensin II and bradykinin on the local vascular release of tissue plasminogen activator (t-PA) and its inhibitor, plasminogen activator inhibitor type 1 (PAI-1), and the endothelium-derived haemostatic factor, von Willebrand factor (vWf) from the forearm. METHODS: Blood flow, and plasma haemostatic and fibrinolytic factors, were measured in both forearms of sixteen healthy men: eight subjects received intra-arterial angiotensin II (5, 50 and 500 pmol/min) which was coinfused with sodium nitroprusside (SNP; 0.3, 1.5 and 7.5 microg/min, respectively), and eight received intra-arterial bradykinin at 10-3000 pmol/min. RESULTS: Despite substantial rises in plasma angiotensin II concentrations (P<0.001) which caused pressor effects (P<0.003) at the highest dose, angiotensin II infusion did not affect local plasma t-PA, PAI-1 or vWf concentrations. In contrast, bradykinin caused substantial dose-dependent increases in blood flow and t-PA release (>100 ng/100 ml of tissue/min) in the infused forearm (P<0. 001 for both) without affecting plasma PAI-1 or vWf concentrations. CONCLUSIONS: Despite high local concentrations with breakthrough of significant systemic effects, angiotensin II did not affect acute endothelial cell t-PA, PAI-1 or vWf release in healthy men. In contrast, bradykinin is a potent vasodilator and selective stimulus for acute local t-PA release. This may, at least in part, explain the fibrinolytic actions of ACE inhibitors in heart failure and ischaemic heart disease.