Anti-ischemic effects of angiotensin-converting enzyme inhibitors: a future therapeutic perspective

Zofenopril in the treatment of patients with arterial hypertension and stable coronary heart disease: effects on oxidative stress and flowdependent vasodilatation

Aim. To compare the effects of ACE inhibitors zofenopril and perindopril on endothelial function and oxidative stress (OS) in patients with stable CHD and AH. Material and methods. In total, 40 patients with stable CHD (Functional Class II-III effort angina) and Stage 1-2 AH received zofenopril (7,5-30 mg/d; mean dose 18,6±8,8 mg/d; n=17) or perindopril (2-8 mg/d; mean dose 4,1±2,1 mg/d; n=23) for 12 weeks. At baseline and in the end of the study, all patients underwent reactive hyperemia test (RHT), to assess flow-dependent vasodilatation of brachial artery, and the measurement of OS parameters (malone dialdehyde, MDA, in low-density lipoproteins, MDALDL) and antioxidant parameters (superoxide dismutase (SOD) and glutathione peroxidase (GPO) activity in erythrocytes).

Results. In both groups, a similar reduction in systolic and diastolic blood pressure levels was observed. In the zofenopril group, a significant elevation in brachial artery diameter increase during RHT, a significant increase in GPO activity, and some reduction in MDALDL levels were observed, which points to antioxidant system (AOS) activation and OS reduction. No similar changes of these parameters were observed in the perindopril group. Conclusion. In patients with stable CHD and AH, zofenopril, but not perindopril, reduced OS severity and increased AOS system activity, which was associated with improved endothelial-dependent vasodilatation.

Effects of zofenopril on cardiac sarcoplasmic reticulum calcium handling

Isolated rat hearts were perfused for 120 minutes in the presence or in the absence of 10 microM zofenoprilat, the active metabolite of zofenopril. At the end of perfusion, cardiac tissue was used to assay sarcoplasmic reticulum (SR) (45)Ca uptake and SR calcium release, which was determined by automatized quick filtration technique after SR vesicle loading with (45)Ca. The expression of genes involved in the control of calcium homeostasis was evaluated by polymerase chain reaction after reverse transcription. In chronic experiments, SR (45)Ca uptake and gene expression were measured in hearts derived from rats treated with 15 mg*kg(-1)*day(-1) zofenopril for 15 days. Acute or chronic zofenopril administration did not produce any change in contractile performance. In acute experiments, SR (45)Ca uptake was significantly increased after exposure to zofenoprilat. The rate constant of calcium-induced calcium release was slightly although not significantly higher, and the calcium leak measured under conditions promoting SR channel closure was significantly increased. In the chronic model, significant increase in the rate of SR (45)Ca uptake was confirmed. Gene expression was not modified, except for decreased phospholamban expression, which is observed in the acute but not in the chronic model. In conclusion, zofenopril increases SR calcium cycling and stimulates active calcium uptake into the SR.

The role of zofenopril in myocardial protection during cardioplegia arrest: an isolated rat heart model

BACKGROUND

Zofenopril has beneficial effects in acute myocardial infarction, and improves the functional recovery after ischemia and reperfusion.

AIM OF THE STUDY

The aim of this study was to investigate the cardioprotective effects of zofenopril, when added to a standard cardioplegic solution or when orally administered as pretreatment.

METHODS

A Langendorff model for isolated rat hearts was employed: three groups of eight hearts each were used, respectively, with plain St. Thomas cardioplegia as control (group A and C), and the same solution added with 12.5 mg of zofenopril (group B). The third group (C) was pretreated for 7days with oral administration of zofenopril (6.5 mg/day). The hearts had a baseline perfusion for 30 minutes with Krebs-Henseleit solution at 37 degrees C, cardioplegia administration for 3 minutes, then 30 minutes of ischemia without any perfusion, and finally 30 minutes of reperfusion with Krebs-Henseleit solution at 37 degrees C.

RESULTS

Left ventricle developed pressure was significantly higher in the reperfusion period only in the pretreated group (group C) with respect to groups A and B (p = 0.016). Similar results were obtained regarding dP/dt curves (p = 0.020). No differences were demonstrated between groups for cellular viability expressed as creatine phospho-kinase (p = ns) and lactate dehydrogenase release (p = ns).

CONCLUSIONS

Zofenopril as oral pretreatment showed protective effects in an isolated model of cardioplegic arrest, although improvements in myocardial viability (enzymatic release) could not be demonstrated. Further experimental and clinical evaluations are necessary to assess the direct cardioprotective effect of zofenopril, modifying the length of treatment and the dosage of the drug.

Peptides and hydrolysates from casein and soy protein modulate the release of vasoactive substances from human aortic endothelial cells

Food proteins were shown to affect atherogenic risk factors, which is supposed to be related to specific peptide sequences encrypted within their primary sequence. The aim of this study was to evaluate the effects of peptides and hydrolysates from two food proteins, casein and soy protein, on endothelial cell functions (cell proliferation and release of vasoactive substances). Cell proliferation was not influenced by dipeptides and most of the tripeptides, whereas several total hydrolysates from casein and soy protein inhibited cell proliferation at higher concentrations (>0.25 mg/mL; P<0.05). The release of one or more of the vasoactive substances, thromboxan B2 (stable marker of thromboxan A2), 6-keto-prostaglandin F1alpha (stable marker of prostaglandin I2), endothelin-1, and nitric oxide, was significantly influenced by the incubation with various peptides compared with control cells (P<0.05). Various hydrolysate fractions from casein and soy protein influenced the release of 6-keto-prostaglandin F1alpha and nitric oxide (P<0.05) but did not influence the release of thromboxan B2 and endothelin-1. In conclusion, the present study demonstrates that peptides and hydrolysate fractions from casein and soy protein influence endothelial cell function as evidenced by the modulation of endothelial cell proliferation and alterations in the release of vasoactive substances.

Cardioprotective effect of zofenopril in perfused rat heart subjected to ischemia and reperfusion

We investigated the effect of different ACE inhibitors on tissue injury in isolated rat hearts subjected to 30 minutes of ischemia followed by 120 minutes of reperfusion. Zofenoprilat (1-100 microM), but not enalaprilat or lisinopril, significantly reduced infarct size, as estimated on the basis of triphenyltetrazolium chloride staining. The protection was not reproduced by the angiotensin II receptor antagonist irbesartan, and it was partly abolished by the bradykinin receptor antagonist HOE 140. Zofenoprilat molecule contains a sulfhydryl group, and its administration, as compared with enalaprilat or lisinopril administration, was associated with better preservation of protein thiols at the end of ischemia. We conclude that zofenopril has a specific cardioprotective effect, which might be related either to interference with bradykinin metabolism or to preservation of protein sulfhydryl groups.

Atherothrombosis: Epidemiology, Pathophysiology, and Prevention

OBJECTIVES

To review the pathophysiology of atherothrombosis (atherosclerosis with superimposed platelet-rich thrombus formation) and the measures that can be taken to prevent its clinical sequelae through lifestyle modifications and pharmacotherapy, with emphasis on the role of antiplatelet agents.

DATA SOURCES

Recent (1995-2003) published scientific literature, as identified by the authors through Medline searches using the terms atherothrombosis, pathophysiology, risk factors, prevention, and reviews on treatment.

STUDY SELECTION

Recent systematic English-language review articles were screened for relevant material.

DATA SYNTHESIS

Atherothrombosis is a generalized and diffuse progressive process affecting multiple vascular beds; its clinical consequences, including acute coronary syndromes (unstable angina, acute myocardial infarction, and sudden cardiac death), ischemic stroke, and peripheral arterial disease, are unpredictable in their time course and potentially life-threatening. Atherothrombosis rather than arterial stenosis appears to account for most of the acute ischemic manifestations of the atherosclerotic process. Interventions that can favorably influence atherosclerotic progression include lifestyle modifications (dietary control, exercise, and smoking cessation) and pharmacotherapy (lipid-lowering, antihypertensive, antiglycemic, and antiplatelet drugs). The pivotal role played by the platelet in thrombus formation provides the rationale for employing antiplatelet drugs with complementary modes of action (e.g., aspirin, clopidogrel) to prevent atherothrombosis.

CONCLUSION

Ischemic cerebrovascular, coronary, and peripheral arterial disease can be regarded as diverse manifestations of a common underlying systemic pathology, namely atherothrombosis. Secondary prevention of an ischemic event in an affected arterial bed confers the added benefit of primary prevention against potential ischemic events in other arterial beds.

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.

An AT1-receptor antagonist and an angiotensin-converting enzyme inhibitor protect against hypoxia-induced apoptosis in human aortic endothelial cells through upregulation of endothelial cell nitric oxide synthase activity

The protective effects and roles of AT1-receptor antagonists (AT1-RA) or angiotensin-converting enzyme inhibitors (ACEI) on vascular endothelial cell (EC) injury during hypoxia are not entirely known. Therefore, we investigated these effects and mechanisms in human aortic (HA) EC. DNA fragmentation, Lactate dehydrogenase (LDH) release, and caspase-3 activity were measured in cultured HAEC after exposure to hypoxia in the presence or absence of an AT1-RA (candesartan, CS) and/or an ACEI (temocaprilat, TC). Next, we investigated endothelial cell nitric oxide synthase (ecNOS) and inducible (i) NOS to determine the role of the bradykinin(BK)-NO pathway in the protective effect on ACEI and AT1-RA in the setting of hypoxia-induced apoptosis. Exposure to hypoxia increased DNA fragmentation in HAEC associated with the activation of caspase-3, but did not affect LDH release. In addition, hypoxia induced ecNOS mRNA but not mRNA iNOS. CS and/or TC reduced apoptosis induced by hypoxia in a dose-dependent manner, and significantly increased BK and ecNOS expression. This effect was attenuated by the kinin B2 receptor antagonist, HOE 140, and the NOS inhibitor, N-nitro-L-arginine methylester (L-NMMA). Hypoxia activates the pathway leading to apoptosis by enhancing caspase-3 activity. Both CS and TC can ameliorate hypoxia-induced apoptosis in HAEC through inhibiting caspase-3 activation by enhancing ecNOS activity, via the accumulation of BK.

Endothelial activation by angiotensin II through NFkappaB and p38 pathways: Involvement of NFkappaB-inducible kinase (NIK), free oxygen radicals, and selective inhibition by aspirin

Angiotensin-II (AII), the dominant effector of the renin-angiotensin system, is involved in the pathogenesis of cardiovascular diseases, such as atherosclerosis. Upregulation of the adhesion molecules VCAM-1, ICAM-1, and E-selectin in endothelial cells by inflammatory cytokines through nuclear factor kappa B (NFkappaB) activation is implicated in formation and progression of atherosclerotic plaque. Here we show that AII induces NFkappaB-dependent transcription in primary endothelial cell lines, leading to the upregulation of ICAM-1 and VCAM-1 expression. NFkappaB activation by AII is mediated by the NFkappaB-inducing kinase (NIK), a common mediator of NFkappaB activation by inflammatory cytokines, such as TNF-alpha. However, NFkappaB stimulation by AII differs from that of TNF-alpha since a TNF-receptor associated factor 2 (TRAF-2) dominant negative mutant does not prevent AII-mediated NFkappaB activation. In analogy with TNF-alpha-dependent activation of NFkappaB, treatment with either the anti-oxidant N-acetyl cysteine (NAC) or the cyclooxygenase (COX) inhibitor acetyl salicylic acid (aspirin), but not indometacin, prevents the induction of NFkappaB-dependent transcription by AII. Thus, production of reactive oxygen species, aspirin (asp)-sensitive enzymes of the arachidonate metabolism, and NIK are common transducers of AII- and TNF-dependent pathways to NFkappaB. AII also activates the inflammatory p38 kinase in endothelial cells, an effect inhibited by exposure to either NAC or asp. Pharmacological interference of the p38 pathway, with the inhibitor SB 202190, prevented AII-mediated activation of the NFkappaB target V-CAM, without affecting degradation of IkappaBalpha. These results support a pro-inflammatory effect of the vasoactive peptide AII in endothelial cells, through at least two pathways-NFkappaB and p38-both of which are sensitive to asp and antioxidants.

Effects of the early ACE inhibition in diabetic nonthrombolyzed patients with anterior acute myocardial infarction

OBJECTIVE

The aim of the present study was to evaluate the clinical efficacy of the ACE inhibitor zofenopril in a cohort of diabetic patients with nonthrombolyzed anterior acute myocardial infarction who were enrolled in the Survival of Myocardial Infarction Long-Term Evaluation (SMILE) trial.

RESEARCH DESIGN AND METHODS

Among the overall population of 1,512 patients, 303 (20.0%) had diabetes. The primary end point of this study was the effect of treatment on the 6-week combined occurrence of death and severe congestive heart failure (CHF). Secondary end points included the evaluation of the 6-week rate of major cardiovascular events as well as the 1-year survival rate.

RESULTS

After 6 weeks of double-blind treatment, zofenopril significantly reduced both the incidence of the primary end point (8.6 vs. 18.3%; P = 0.019) and the 6-week incidence of severe CHF (0 vs. 7.3%; P = 0.001) in diabetic patients, and the effect was greater than that observed in nondiabetic patients. Conversely, 1-year mortality was significantly reduced among nondiabetic patients (9.1 vs. 13.8%; P = 0.010), whereas in the diabetic population, the decrease did not reach statistical significance (13.7 vs. 16.5%; P = 0.52).

CONCLUSIONS

The present data suggest that the clinical outcome of patients with diabetes and myocardial infarction can be significantly improved by early treatment with zofenopril. The lesser effect on 1-year mortality seems to suggest that long-term treatment is probably needed to maintain the benefits of the early ACE inhibition in patients with diabetes.

Inflammatory pathways in atherosclerosis and acute coronary syndromes

Evidence from a broad range of studies demonstrates that atherosclerosis is a chronic disease that, from its origins to its ultimate complications, involves inflammatory cells (T cells, monocytes, macrophages), inflammatory proteins (cytokines, chemokines), and inflammatory responses from vascular cells (endothelial cell expression of adhesion molecules). Investigators have identified a variety of proteins whose levels might predict cardiovascular risk. Of these candidates, C-reactive protein, tumor necrosis factor-alpha, and interleukin-6 have been most widely studied. There is also the prospect of inflammation as a therapeutic target, with investigators currently debating to what extent the decrease in cardiovascular risk seen with statins, angiotensin-converting enzyme inhibitors, and peroxisome proliferator-activated receptor ligands derives from changes in inflammatory parameters. These advances in basic and clinical science have placed us on a threshold of a new era in cardiovascular medicine.