Effect of antihypertensive therapy using enalapril or losartan on haemostatic markers in essential hypertension: a pilot prospective randomised double-blind parallel group trial

Amlodipine alters hemorheological parameters: Increased efficacy at the cost of edema?

Background

Despite several decades of use of calcium channel blockers, the side effect of edema persists as a class effect, and its mechanism is unresolved. Amlodipine has effects on hemorheology (HR), and its hemodilutory property may partly contribute to its antihypertensive action. This aspect is not well studied, and the literature is sparse in this regard.

Objective

This experiment was planned to determine effect of a single-dose administration of amlodipine on HR parameters in normal human volunteers.

Methods and results

Amlodipine (5 mg) or S (-) amlodipine (2.5 mg) was administered to 27 normal human volunteers. Whole-blood viscosity (WBV) at different shear rates, plasma viscosity (PV), red cell rigidity (RCR), red cell aggregation (RCA), hematocrit (Hct), plasma hemoglobin, along with plasma drug concentration were determined at time intervals, t = 0, 4, 8, 12, and 24 h. Statistically significant reductions were observed at t_max = 4 h in WBV at shear rates of 0.512 s^–1 (p < 0.005), WBV at shear rates of 5.26 s^–1 (p < 0.01), PV (p < 0.05), and Hct (p < 0.01). At t = 8 h, as drug concentration reduced, some of the changes persisted and later slowly decreased with the decreasing drug concentration till t = 24 h. Red blood cell–related parameters such as RCA and RCR remained unaltered. WBV values at all shear rates, when corrected for Hct = 0.45, did not show deviation from their original values at any time.

Conclusions

Amlodipine causes a reduction in Hct and blood viscosity, along with hemodilution. These effects persist as long as the drug remains in plasma. Edema resulting from chronic dosing may be explained by the aforementioned effects. It is possible that antihypertensive action of the drug may be due to a combination of vasodilatation and an improvement in the HR properties.

Potential Protective Role of Blood Pressure-Lowering Drugs on the Balance between Hemostasis and Fibrinolysis in Hypertensive Patients at Rest and During Exercise

In patients with hypertension, the triad represented by endothelial dysfunction, platelet hyperactivity, and altered fibrinolytic function disturbs the equilibrium between hemostasis and fibrinolysis and translates into a hypercoagulable state, which underlies the risk of thrombotic complications. This article reviews the scientific evidence regarding some biological effects of antihypertensive drugs, which can protect patients from the adverse consequences of hypertensive disease, improving endothelial function, enhancing antioxidant activity, and restoring equilibrium between hemostatic and fibrinolytic factors. These protective effects appear not to be mediated through blood pressure reduction and are not shared by all molecules of the same pharmacological class.

Inhibition of renin-angiotensin axis reduces the risk of thrombus formation in the left atrial appendage in patients with hypertension complicated by atrial fibrillation

Aims:

We examined whether the use of a renin-angiotensin-aldosterone system (RAS) inhibitor plays a role in protecting against left atrial appendage thrombus (LAAT) in patients with hypertension complicated by atrial fibrillation (AF).

Methods:

Two observational studies were conducted on patients with diagnoses of hypertension and AF, who were categorized into RAS inhibitor user or nonuser groups. Demographic characteristics, clinical characteristics, echocardiographic parameters and hemostatic markers were examined and the occurrence of LAAT during follow-up were recorded.

Results:

In the first study (n = 131), LA peak systolic strain and LAA emptying flow velocity (LAA eV) were significantly increased in patients on RAS inhibitors compared with the nonuser group (p < 0.05). Lower D-dimer and fibrinogen levels were observed in patients on RAS inhibitors (p < 0.05). In the second study (n = 99), 25.9% (n = 11) of patients on RAS inhibitors developed LAAT, compared with 46.7% (n = 21) in the nonuser group (p < 0.05). After controlling for risk factors related to LAAT, use of RAS inhibitors remained associated with a significantly lower risk of developing LAAT (HR, 0.406; 95% CI, 0.191–0.862; p = 0.019).

Conclusions:

RAS inhibitors use was associated with a significant reduction in the risk of LAAT in patients with hypertension and AF.

Endothelial Damage and Hemostatic Markers in Patients with Uncomplicated Mild-to-Moderate Hypertension and Relationship with Risk Factors

Endothelial damage, high fibrinogen levels, and platelet activity are the important accelerating factors for the development of hypertension (HT). von Willebrand factor (vWF; endothelial damage marker), fibrinogen levels, and platelet aggregability were compared between patients with uncomplicated, mild-to-moderate hypertension and healthy subjects. The relationship between traditional cardiovascular risk factors and endothelial damage and prothrombotic state was evaluated. One hundred sixty-nine (54 males, 115 females) patients with untreated and uncomplicated mild-to-moderate HT, and age, gender, and body mass index-matched 124 (58 males, 83 females) healthy subjects were enrolled in this study. Plasma vWF, fibrinogen levels, adenosine diphosphate-induced platelet aggregability, insulin, glucose, serum lipids, and uric acid were measured. Patients with HT had significantly increased fibrinogen, vWF, platelet number and aggregability induced by adenosine diphosphate, triglycerides, total/HDL-C, glucose, uric acid levels, and insulin resistance than control group. vWF and hemostatic markers were comparable between smoker and nonsmoker subjects. Platelet aggregability was positively related to systolic and diastolic blood pressure, and vWF. Fibrinogen was positively associated with body mass index (BMI), systolic and diastolic blood pressure, total cholesterol (TC), uric acid, vWF, and insulin resistance. vWF was significantly related to age, systolic blood pressure, TC, LDL-C, and total/HDL-C. Systolic blood pressure was independently related to vWF. vWF and diastolic blood pressure were significant predictors for adenosine diphosphate-induced platelet aggregability. Systolic blood pressure and vWF were independent predictors for fibrinogen levels. Uncomplicated mild-to-moderate HT had endothelial damage and is associated with a prothrombotic state. Traditional cardiovascular risk factors such as age, BMI, dyslipidemia, and insulin resistance are important contributors to the development of endothelial damage and a prothrombotic state. Therefore, it is important to control these cardiovascular risk factors along with proper treatment of HT for preventing target organ damage in mild-to-moderate HT.

Antithrombotic effects of losartan in patients with hypertension complicated by atrial fibrillation: 4A (Angiotensin II Antagonist of platelet Aggregation in patients with Atrial fibrillation), a pilot study

Angiotensin receptor blockers (ARBs) are widely used for the treatment of hypertension. It has been reported that the ARB losartan has antiplatelet, anticoagulant and profibrinolytic effects experimentally. These properties could be desirable to treat hypertensive patients with high atherothrombotic and/or thromboembolic risk. To examine the antithrombotic effects of losartan in hypertension, 20 consecutive patients with hypertension complicated by atrial fibrillation (AF) were enrolled in this study. The patients were treated with losartan 50 mg for 8 weeks followed by 100 mg for 4 weeks. Blood samples were obtained from each patient at 0 (pretreatment), 8 and 12 weeks after initiating treatment. Platelet aggregability, plasma levels of tissue factor (TF) and type 1 plasminogen activator inhibitor (PAI-1) activity levels were measured. The area under the curve for small platelet aggregability decreased from 100 to 42.8% at 12 weeks (P<0.0001). TF levels (ng ml(-1)) and PAI-1 activity (IU ml(-1); mean±s.d.) also changed from 14.2±3.6 to 10.9±4.5 at 12 weeks (P=0.0299) and from 11.7±3.6 to 8.5±3.1 at 12 weeks (P=0.0122), respectively. Losartan inhibited platelet activity and coagulation factors in a dose- and time-dependent manner in patients with hypertension complicated by AF, whereas the fibrinolytic capacity was increased. The use of losartan could be advantageous in the treatment of hypertensive patients with high atherothrombotic risk.

Circulating levels of cell adhesion molecules in hypertension

Hypertension causes complications such as coronary atherosclerosis and thrombosis wherein inflammatory factors play significant role. In the present study inflammatory molecules such as cell adhesion molecules (CAMs); endothelial (E)-selectin, platelet (P)-selectin, intercellular CAM-1 (ICAM-1), vascular CAM-1 (VCAM-1) and platelet endothelial CAM-1 (PECAM-1) were analysed in subjects newly diagnosed with hypertension with no secondary cause against normotensive healthy individuals. In each group 57 subjects were recruited and soluble (s) levels of CAMs were analysed by ELISA. As compared to controls median of sE-selectin (49.2%, P=0.001), sP-selectin (54.3%, P=0.001), and sICAM-1 (18.9%, P=0.012) were significantly elevated in hypertensive subjects. Significant negative correlation was observed of sP-selectin (spearman rank correlation coefficient (rs) =-0.345, p=0.027) and sPECAM-1 (rs =-0.446, p=0.003) with age in hypertension group. Hypertension may increase expression of certain CAMs while younger hypertensives in addition are also at increased risk of atherothrombosis.

Obstructive sleep apnea and cardiovascular disease

Obstructive sleep apnea (OSA) is a common yet an under-diagnosed sleep related breathing disorder affecting predominantly middle-aged men. OSA is associated with many adverse health outcomes, including cardiovascular disease. Common OSA associated/induced cardiovascular disorders include coronary artery disease, heart failure, hypertension, cardiac arrhythmias and stroke, which further increase morbidity and mortality in the OSA population. Endothelial dysfunction, coagulopathy, impaired sympathetic drive, oxidative and inflammatory stress are the pathophysiological pathways suggested for the development of cardiovascular disease in OSA. The evidence would suggest that OSA should be considered as a cardiovascular risk factor, and is a treatable condition. Multiple studies using Continuous Positive Airway Pressure (CPAP) have shown improvements in the clinical state as well as retardation of disease progression. Therefore, patients with cardiovascular disease should be proactively screened for OSA and vice versa.

Markers of endothelial dysfunction in children with idiopathic nephrotic syndrome

Endothelial function impairment may constitute a link between nephrotic syndrome and atherosclerosis. We assessed changes in plasma thrombomodulin, von Willebrand factor and plasminogen activator inhibitor-1 at different stages of idiopathic nephrotic syndrome in children and correlated them with clinical and biochemical parameters. The study group included 132 nephrotic children (aged 2-18 years) divided into four groups, i.e. in acute phase of the disease with proteinuria, during steroid-induced remission, steroid-free remission, and in long-term, steroid-free remission. Forty-one healthy children served as controls. Plasma thrombomodulin, plasminogen activator inhibitor-1 and von Willebrand factor activity were increased in children with early nephrotic relapse. They systematically decreased in later stages of the disease but the increase in von Willebrand factor persisted in drug-free remission. These disturbances were dependent on the degree of proteinuria and serum albumin concentration. The study revealed that nephrotic children show markers of endothelial dysfunction that are dependent on the disease activity. This leads to the hypothesis that children with severe clinical course of nephrotic syndrome may be at high risk of accelerated atherogenesis.

Elevation of serum soluble E- and P-selectin in patients with hypertension is reversed by benidipine, a long-acting calcium channel blocker

Hypertension is a major risk factor for atherosclerotic cardiovascular disease. Selectins, cell-surface adhesion molecules involved in leukocyte rolling and attachment to the vascular endothelium, play a role in the initiation of atherosclerosis. We investigated whether or not serum levels of soluble adhesion molecules are elevated in patients with essential hypertension (EH) and examined whether antihypertensive therapy lowers such levels. Twenty-one patients who had untreated mild to moderate EH without diabetes mellitus, hyperlipidemia, or obesity were recruited at a clinic for hypertensive patients. Blood pressure was measured, and the serum levels of soluble E-selectin, P-selectin, L-selectin, intercellular adhesion molecule 1 (ICAM-1), and vascular-cell adhesion molecule 1 (VCAM-1) were determined by enzyme-linked immunosorbent assays before and after 12, 24, and 53 weeks of antihypertensive treatment with benidipine, a long-acting calcium channel blocker, given at a dose of 6 mg/day for 53 weeks. As a control, 21 age- and sex-matched patients without hypertension were studied. Serum E- and P-selectin levels were significantly higher in the subjects with EH than in the controls (p < 0.01). There were no differences in serum levels of soluble L-selectin, VCAM-1, or ICAM-1 levels between the patients with EH and the controls. Treatment with benidipine decreased the elevated blood pressure over a 53-week study period (mean blood pressure: 119.8 +/- 6.5 mmHg at baseline, 101.0 +/- 5.9 mmHg at 12 weeks, 98.6 +/- 7.3 mmHg at 24 weeks, and 93.9 +/- 5.5 mmHg at 53 weeks). Serum levels of soluble E- and P-selectin decreased after the initiation of benidipine treatment and correlated with diastolic blood pressure. Serum levels of soluble L-selectin, VCAM-1, and ICAM-1 did not change significantly during the period of benidipine treatment. Benidipine treatment reduced the content of P-selectin in the platelets from patients with EH, as determined by Western blot analysis. In conclusion, decreased blood pressure may reduce the rate of progression of atherosclerosis by affecting the expression of E- and P-selectin in the endothelium, the platelets, or both. Benidipine may be protective against vascular damage in people with hypertension, not only by lowering blood pressure, but also by inhibiting the expression of selectins.

Vascular and metabolic effects of candesartan: insights from therapeutic interventions

BACKGROUND

Effects of angiotensin II type 1 receptor blockers (ARBs) to improve endothelial dysfunction may be due to mechanisms in addition to the reduction of high blood pressure per se. Endothelial dysfunction is characterized by vascular inflammation that contributes to clinically significant atherosclerosis and by an increased tendency for thrombus formation. Hypertensive patients have impaired endothelial functions that have positive predictive power with respect to future cardiovascular events.

OBJECTIVES

The present review will focus on multiple mechanisms underlying vascular and metabolic effects of ARBs that may synergize to prevent or regress atherosclerosis, onset of diabetes, and coronary heart disease.

CONCLUSIONS

Angiotensin II accelerates the development of atherosclerosis by activating angiotensin II type 1 receptors that then promote superoxide anion generation and oxidative stress, leading to activation of nuclear transcription factor and endothelial dysfunction. Activation of angiotensin II type 1 receptors also stimulates increased expression of plasminogen activator inhibitor type 1 and tissue factor. Endothelial dysfunction associated with the metabolic syndrome and other insulin-resistant states is characterized by impaired insulin-stimulated production of nitric oxide from the endothelium and decreased blood flow to skeletal muscle. Increasing insulin sensitivity therefore improves endothelial function, and this may be an additional mechanism whereby ARBs decrease the incidence of coronary heart disease and the onset of diabetes. Adiponectin serves to link obesity with insulin resistance. In addition, adiponectin has anti-atherogenic properties.

New risk factors for atherosclerosis in hypertension: focus on the prothrombotic state and lipoprotein(a)

Although adequate control of blood pressure is of basic importance in cardiovascular prevention in hypertensive patients, correction of additional risk factors is an integral part of their management. In addition to classical risk factors, epidemiological research has identified a number of other conditions that might significantly contribute to cardiovascular risk in the general population and might achieve specific relevance in patients with high blood pressure. In fact, more than 20% of patients with premature cardiovascular events do not have any of the traditional risk factors and, although effective intervention on blood pressure and additional risk factors has significantly reduced cardiovascular morbidity and mortality, the contribution to stroke, coronary artery disease and renal failure is still unacceptably high. Evaluation of new risk factors may further expand our capacity to predict atherothrombotic events when these factors are included along with the traditional ones in the assessment of global cardiovascular risk in hypertensive patients. Because it could be anticipated that the role of these novel factors will become increasingly evident in the future, researchers with an interest in hypertension and physicians dealing with problems related to cardiovascular prevention should give them appropriate consideration. This review summarizes the basic biology and clinical evidence of two emerging risk factors that are reciprocally related and contribute to the development and progression of organ damage in hypertension: the prothrombotic state and lipoprotein(a).

Endothelial function and its assessment

Endothelial dysfunction is a characteristic aspect of most of the conditions associated with atherosclerosis and is commonly found as an early feature in atherothrombotic vascular disease. An appreciation of the underlying mechanisms of endothelial function, as well as dysfunction, is essential as this has critical influence on the different methods in the assessment of endothelial function and effects of various treatments on its quantification. Furthermore, endothelial dysfunction is recognised as a type of 'target organ damage' in common cardiovascular conditions (e.g., hypertension) and the area is of increasing interest for new drug development, as therapies that modulate the endothelium will have added advantages; thus, for the development of new/experimental drugs, an awareness of ways to assess the endothelium is necessary. In this review, an overview of different methods including biochemical markers, and invasive and non-invasive tools, to determine endothelial function is presented as well as their clinical relevance. Furthermore, the effects of various treatments on endothelial dysfunction and their underlying mechanisms are elucidated.

Cyclosporin A does not affect platelets in children with idiopathic nephrotic syndrome

The immunosuppressive agents administered to maintain the remission of idiopathic nephrotic syndrome (INS) may have a deleterious effect on several cell types. The aim of this study was to analyze platelet activation and reactivity in children with INS treated with cyclosporin A (CyA). The study groups comprised 16 children with remission of INS induced by CyA and 16 children with glucocorticosteroid-induced remission 8 weeks from the onset of INS relapse. Fifteen healthy children served as controls. Surface expression of CD61, CD62P, and CD42b on resting and thrombin-stimulated platelets was analyzed with flow cytometry. No differences between groups were found in CD61, CD62P, and CD42b surface expression, but markers of the coagulation cascade and fibrinolysis or endothelial injury (F1+2 prothrombin fragments, tissue plasminogen activator inhibitor 1) were elevated in patients treated with CyA compared with children on steroids and healthy controls. No correlations between markers of platelet function and CyA concentration were found. We postulate that CyA administration in nephrotic patients causes an activation of thrombinogenesis but does not influence platelet activation and reactivity in INS.

Is the effect of antihypertensive drugs on platelet aggregability and fibrinolysis clinically relevant?

Hypertension is associated with decreased fibrinolytic potential, mainly expressed as elevated plasma plasminogen activator inhibitor type 1 (PAI-1) levels, and increased platelet aggregability, which may account in part for the increased risk of atherosclerosis and its clinical complications in hypertensive patients. The effects of antihypertensive drugs on this prothrombotic state have been investigated and controversial findings have been reported, possibly because of differences in study designs, patients selected, and methodology used. Scarce and conflicting data exist about the effects of diuretics and beta-adrenoceptor antagonists on the fibrinolytic system, whereas ACE inhibitors have generally been reported to improve the fibrinolytic balance by decreasing plasma PAI-1 levels, calcium channel antagonists have been shown to increase tissue plasminogen activator (tPA) activity, and angiotensin II type 1 (AT(1)) receptor antagonists seem to exert neutral effects. beta-Adrenoceptor antagonists, calcium channel antagonists, and AT(1)-receptor antagonists have been reported to exert anti-aggregatory effects on platelets, while contrasting data exist about the influence of ACE inhibitors. Clinical implications of the changes induced by antihypertensive drugs on the fibrinolytic balance and platelet function are still debated. In particular, the question of whether these changes may translate into different degrees of cardiovascular protection in hypertensive patients remains unanswered. While awaiting more information from clinical trials, the choice of antihypertensive drugs, particularly in high-risk patients, should take into account effects beyond their BP-lowering efficacy. Selected agents should have a favorable, or at least neutral, impact on fibrinolytic function and platelet activity.

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.

Platelet and haemorheological markers in 'high risk' hypertensives are improved by tighter blood pressure control and cardiovascular risk management: a substudy of the Anglo-Scandinavian Cardiac Outcomes Trial (ASCOT)

OBJECTIVE

To investigate the impact of intensified cardiovascular risk management on soluble markers of platelet, endothelial and rheological function in a population of middle-aged hypertensive patients at high risk of cardiovascular complications.

DESIGN

Prospective follow-up study.

SUBJECTS AND METHODS

A total of 159 hypertensive patients [138 male, mean age 64 (+/-8) years] and 80 healthy controls were studied. Plasma levels of soluble P-selectin (sP-sel, a marker of platelet function), von Willebrand factor (vWF, an index of endothelial damage/dysfunction) and rheological indices [fibrinogen (Fib), plasma viscosity (PV), haematocrit (HCT), white blood count (WBC) and platelet count] were measured at baseline and again (in the patients) after 6 months' treatment.

RESULTS

As expected, 6 months of intensified cardiovascular risk management resulted in a significant fall in mean blood pressure (BP) and total cholesterol. It also resulted in reduced haematocrit, vWF, sP-sel, WBC and PV levels (all P < 0.001), but not plasma fibrinogen. There were no correlations between the fall in BP and the improvement in any of the research indices.

CONCLUSIONS

Intensified cardiovascular risk management results in significant improvements in indices of endothelial, platelet and rheological function in a population of hypertensives at high risk of cardiovascular events. These improvements appear to be independent of the degree of change in BP. Given the fundamental role of interactions between the endothelium and circulating blood components in the pathogenesis of hypertensive complications this may be of importance in preventing adverse cardiovascular outcomes.

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.

A Double Blind Randomized Trial to Compare the Effects of Eprosartan and Enalapril on Blood Pressure, Platelets, and Endothelium Function in Patients With Essential Hypertension

The renin-angiotensin system is the major contributor to development of hypertension, atherosclerosis, and many other cardiovascular diseases. Angiotensin II, one of the main effectors of this system, contributes to the pathogenesis of hypertension and plays an important role in monocyte, platelet, and endothelium interactions. The effects on platelet and endothelial function, either by angiotensin converting enzyme inhibitors or angiotensin receptor antagonists, are still not well understood. A double-blind, randomized, prospective trial of either enalapril (10-20 mg daily) or eprosartan (400-800 mg daily) over a 10-week period was conducted in 42 patients (27 males, 15 females). Platelet activation was evaluated by measuring platelet factor 4 (PF-4), beta-thromboglobulin (beta-TG), the ratio of platelet factor 4 to beta-thromboglobulin, and endothelial function by measuring total plasma nitrate levels, von Willebrand factor (vWF) levels, and blood flow using venous occlusive plethysmography. After a 10-week treatment with enalapril or eprosartan, the sitting blood pressure in both the enalapril group (from 152.2 +/- 18.7 mmHg to 141.9 +/- 23.5 mmHg, P < 0.05) and eprosartan group (from 151 +/- 10.0 mmHg to 142.3 +/- 12.9 mmHg, P < 0.05) was significantly reduced. Significant diastolic blood pressure (DPB) reduction (from 94 +/- 8.7 to 84.5 +/- 9.6 mmHg, P < 0.05) and a greater DBP reduction response were found in the eprosartan group (63% in eprosartan versus 25% in enalapril). Additionally, dose-dependent reductions in the indices of platelet activation and endothelial dysfunction were observed in patients administered high dose treatments of eprosartan and enalapril, and the beneficial effects of these agents were not correlated with the reduction of blood pressure using both agents. Eprosartan is effective and well-tolerated in the treatment of mid-to-moderate hypertension, and the DBP response reduction to eprosartin was better than that to enalapril. A high dose of either eprosartan or enalapril significantly decreased the indices of platelet activation and endothelial dysfunction in hypertensive patients. The benefits of both agents cannot be explained solely by their antihypertensive effects and possibly may be mediated through their unique effect on angiotensin blockade.

Effects of ACE inhibition and AT1-receptor antagonism on endothelial function and insulin sensitivity in essential hypertensive patients

OBJECTIVE

Disturbed endothelial function is closely associated with hyperinsulinaemia and insulin resistance in essential hypertension. The aims of this study were: 1) to evaluate whether the two alternative drugs, angiotensin-converting enzyme (ACE) inhibitors and Angiotensin II (Ang II) antagonists, had comparable effects on glucose metabolism and endothelial function. 2) to determine whether they improve endothelial dysfunction through modulating insulin resistance and oxidative stress.

STUDY DESIGN AND METHODS

Essential hypertensive patients were randomised into two groups: Twelve (nine patients in final analysis) patients were given enalapril (enalapril group), and twelve (nine patients in final analysis) were given losartan (losartan group). Twelve sex- and age-matched normotensive volunteers were included as controls. Before and after six months of treatment, endothelial function, insulin sensitivity and lipid peroxidation (TBARs) and NO metabolites (NOx) were evaluated.

RESULTS

Endothelial function, measured as flow mediated dilatation (FMD), was improved in both of the treatment groups (p=0.0001). Calculated insulin sensitivity index also improved in the enalapril-treated group (p=0.05) but not in the losartan-treated group, compared with baseline levels. TBARS values decreased significantly in the enalapril group compared with baseline levels (p<0.001). FMD was positively correlated with insulin sensitivity index (r=0.32, p<0.05) and NOx levels (r=0.39, p=0.01) and negatively correlated with TBARS levels (r=-0.53, p=0.0002) in hypertensive patients.

CONCLUSION

Inhibition of the renin-angiotensin system, either with ACE inhibitors or AT(1)-receptor blockers improves endothelial dysfunction. ACE inhibition has prominent effects on improving insulin sensitivity and decreasing oxidative stress in essential hypertensive patients.

Pleiotropic effects of angiotensin II receptor blocker in hypertensive patients

OBJECTIVES

We investigated the vascular effects of candesartan in hypertensive patients.

BACKGROUND

The renin-angiotensin system may contribute to atherogenesis through the promotion of endothelial dysfunction. The plausible mechanisms are that angiotensin II promotes superoxide anion generation, endothelial dysfunction, inflammation, and impaired fibrinolysis. The effects of candesartan on these conditions have not been clearly observed.

METHODS

We administered placebo or candesartan 16 mg daily during two months to 45 patients with mild-to-moderate hypertension. This was a randomized, double-blind, placebo-controlled, crossover study in design.

RESULTS

Candesartan did not significantly change lipoprotein levels. However, compared with placebo, candesartan significantly reduced plasma levels of malondialdehyde from 1.50 +/- 0.07 to 1.29 +/- 0.09 microM (p = 0.009); improved the percent flow-mediated dilator response to hyperemia from 5.17 +/- 0.24 to 6.22 +/- 0.26% (p < 0.001); and, furthermore, reduced plasma levels of monocyte chemoattractant protein (MCP-1) from 213 +/- 8 to 190 +/- 7 pg/ml (p = 0.003), tumor necrosis factor-alpha from 2.93 to 2.22 pg/ml (p = 0.026), and plasminogen activator inhibitor type 1 from 74 +/- 4 to 53 +/- 4 ng/ml (p < 0.001) but not C-reactive protein (CRP), matrix metalloproteinase protein, and fibrinogen. There were no significant correlations between these changes and reduction of systolic blood pressure (BP) (-0.247 < or = r < or = 0.195) and between these changes and reduction of diastolic BP (-0.262 < or = r < or = 0.197). There were no significant correlations between markers of inflammation and flow-mediated dilation percent or reduction of oxidant stress (-0.119 < or = r < or = 0.127). Furthermore, we observed no significant correlations between CRP and MCP-1 levels (r = -0.162).

CONCLUSIONS

Inhibition of the angiotensin II type 1 (AT1) receptor in hypertensive patients reverses endothelial dysfunction, measured as an improvement in flow-mediated dilation and fibrinolysis and reduction of oxidant stress and inflammatory cytokines, suggesting that AT1 receptor blocker therapy has antiatherogenic effects.

Effects of captopril on expression of MMP-2, 3 and TIMP-2, 3 in rat hepatic fibrosis

AIM

To investigate the effects of captopril on the expression of MMP-2, 3 and TIMP-2, 3 in rat hepatic fibrosis.

METHODS

Forty healthy Wistar rats were randomly divided into five groups: normal control group, experiment group A, experiment group B, captopril-prevention group, captopril-treatment group. Hepatic fibrosis models were induced in the latter 4 groups by a combination of several factors. Liver sections were stained by hematoxylin-eosin and Van Gieson to evaluate the degree of inflammation and hepatic fibrosis. Expression of MMP-2, 3 and TIMP-2, 3 in liver were assayed by immunohistochemistry.

RESULTS

There was significant difference between captopril-prevention group(1.33±0.52)and experimental group A (2.17±0.75) on histologic assessment of hepatic fibrosis, and between captopril-treated group (1.67±0.82)and experimental group B (2.86±0.69) (P<0.05). The ratios of positive expression area of MMP-2 in captopril-prevention group and captopril-treatment group (4.43±0.25% and 3.21±0.16%, respectively) was smaller than in experimental group A and B (8.20±0.24% and 5.67±0.32%, respectively), (P<0.01). Expression of MMP-3 in experimental group A and experimental group B (1.54±0.36% and 3.69±0.27%, respectively) was weaker than in captopril-prevention group and captopril-treated group (4.25±0.37% and 10.75±1.69%, respectively) (P<0.01). Expression of TIMP-2 in captopril-prevention group (2.16±0.17%) was weaker than in experimental group A (3.61±0.46%)(P<0.01); but TIMP-2 in captopril-treatment group (7.87±0.59%) was stronger than in experimental group B (6.68±0.52%) (P<0.01). Expression of TIMP-3 in captopril-prevention group and captopril-treatment group (3.06±0.28% and 5.35±0.34%, respectively) was weaker than in experimental group A and experimental group B(4.13±0.29% and 8.54±0.45%, respectively) (P<0.01).

CONCLUSION

Captopril could suppress expression of MMP-2, TIMP-3, and enhance the expression of MMP-3, which might be related with its anti-hepatic fibrosis activity.

Pharmacological modulation of platelet function in hypertension

Platelets exert a considerable influence on human morbidity and mortality. The rationale for their study in hypertension follows the observation that the major consequences of hypertension are stroke and myocardial infarction. However, the etiology of these consequences in hypertension is, paradoxically, not hemorrhagic (as might be expected from the effects of high blood pressure), but occlusive, with thrombus being the culprit lesion. Mechanisms of platelet activation include high shear force, activation of the renin-angiotensin system, endothelial changes, and the presence of comorbidity, such as atrial fibrillation. The treatment of high blood pressure brings about a reversal of the changes seen in the cell. This could be in part due to the direct effect of the drug on the megakaryocyte and/or the platelets themselves, or it might simply be due to the reduction in blood pressure. Some drugs, such as calcium channel antagonists and angiotensin II receptor blockers, however, might have direct effects on platelet biochemistry other than reducing blood pressure. Finally, antiplatelet drugs are becoming an important part of the management of high-risk hypertensives, which aim to minimize vascular complications.

Implications of the LIFE trial

The recent Losartan Intervention For Endpoint Reduction in Hypertension (LIFE) study was conducted in patients with essential hypertension with electrocardiogram evidence of left ventricular hypertrophy. This showed that losartan compared to atenolol resulted in a significant reduction in the primary endpoint of cardiovascular morbidity and mortality, as well as a greater reduction in electrocardiographically-defined left ventricular hypertrophy. Importantly, this was despite a mean blood pressure reduction which was similar in both groups. Furthermore, the atenolol arm was associated with higher incidence of newly diagnosed diabetics. The LIFE study has firmly confirmed a place for losartan (and other angiotensin receptor blockers) in the management of hypertension. Losartan has also been shown to be effective in diabetics and in patients with atrial fibrillation, as well as in left ventricular hypertrophy regression. This trial also raises the possibility that beta-blockers should perhaps not be used as first-line monotherapy.

Effects of Losartan and Delapril on the Fibrinolytic System in Patients with Mild to Moderate Hypertension

BACKGROUND AND OBJECTIVES

Angiotensin-converting enzyme (ACE) probably influences the fibrinolytic system at a central point by converting angiotensin I to angiotensin II, which increases plasminogen activator inhibitor-1 (PAI-1) activity. This effect appears to be mediated in humans via the angiotensin II type 1 (AT(1)) receptor. The objective of this study was to evaluate, in patients with mild to moderate hypertension, the change in tissue plasminogen activator (t-PA) and PAI-1 plasma levels after treatment with an AT(1)-receptor blocker (losartan 50 mg/day) or an ACE inhibitor (delapril 60 mg/day).

PATIENTS AND METHODS

30 hypertensive patients and 15 controls were enrolled. Essential hypertension was established by a medical history, physical examination and the absence of clinical findings suggestive of a secondary form of hypertension. Preliminary investigations, routine biochemical tests (including clearance of creatinine and oral glucose tolerance test), chest x-ray, standard and 24-hour ECG monitoring, M- and B-mode echocardiography and fundus oculi examinations were performed. No patients had previously received ACE inhibitors or AT(1)-receptor blockers. After a 14-day run-in period with placebo, patients were randomised in a double-blind fashion into two groups: 15 patients were randomised to losartan 50 mg/day (group 1), 15 patients were randomised to delapril 60 mg/day (group 2), and 15 healthy subjects were used as controls (group 3). Plasma PAI-1 and t-PA antigen were determined by enzyme-linked immunosorbent assay and a photometric method at the end of the run-in period and after 6 months of treatment.

RESULTS

There were no significant differences among the three groups regarding age, sex, body mass index and smoking. After 6 months, both groups of patients showed a reduction in blood pressure values. The losartan group did not demonstrate significant changes in PAI-1 levels (96.52 +/- 23.73 and 99.89 +/- 22.18 mug/L, pre- and post-treatment, respectively) or in t-PA antigen levels (26.17 +/- 6.18 and 27.32 +/- 5.91 mug/L, pre- and post-treatment, respectively). The delapril group showed no significant changes in PAI-1 levels (97.73 +/- 25.75 and 86.12 +/- 13.12 mug/L, pre- and post-treatment, respectively), but did show a statistically significant difference (p < 0.005) in t-PA antigen levels (25.71 +/- 6.40 and 32.24 +/- 5.31 mug/L, pre- and post-treatment, respectively). The losartan group demonstrated significantly higher post-treatment PAI-1 values than the delapril group (p = 0.048).

CONCLUSION

The study showed that losartan does not affect fibrinolytic parameters, while delapril resulted in an insignificant reduction in PAI-1 and a significant increase in t-PA levels. Further studies are clearly required in order to establish whether these different effects on the fibrinolytic system between ACE inhibitors and AT(1)-receptor blockers may have clinical relevance.

Von Willebrand factor, soluble P-selectin, and target organ damage in hypertension: a substudy of the Anglo-Scandinavian Cardiac Outcomes Trial (ASCOT)

To investigate the relationship between soluble markers of platelet, endothelial and rheological function, and target organ damage and their response to intensified management in a population of middle-age hypertensive patients at high risk of cardiovascular complications, we studied 382 consecutive patients (308 men; mean age, 63 years, SD 8) along with 60 normotensive controls free of cardiovascular disease. Patients were divided into those with target organ damage (TOD; n=107) and those free of end-organ damage. Plasma levels of soluble P-selectin (sP-sel), a marker of platelet activation, and von Willebrand factor (vWF), an index of endothelial damage/dysfunction (both enzyme-linked immunosorbent assay), and the rheological indices fibrinogen, plasma viscosity, hematocrit, platelet, and white cell count were measured. In 53 patients, variables were further measured after 6 months of intensified cardiovascular risk management. Patients with TOD had significantly higher vWF, 137 (SD 33) versus 125 (SD 33) IU/dL (P=0.002,) and a greater proportion of smokers, 31% versus 16% (P=0.002). There were no statistically significant differences in plasma viscosity, fibrinogen, hematocrit, white blood cell count, platelet count, or sP-sel between the 2 subgroups. In multivariate analysis, vWF was a significant independent predictor for TOD. After 6 months of intensified management in 53 patients who entered the trial, there were significant reductions in systolic blood pressure, total cholesterol, hematocrit, plasma viscosity, sP-sel, and vWF (all P<0.01) but no significant change in fibrinogen. In conclusion, there is a relationship between TOD and endothelial damage/dysfunction in hypertension. Intensified management results in improvements in hemorheology, endothelial and platelet function.