High tissue affinity angiotensin-converting enzyme inhibitors improve endothelial function and reduce infarct size

Endothelial dysfunction: molecular mechanisms and clinical implications

Cardiovascular disease (CVD) and its complications are a leading cause of death worldwide. Endothelial dysfunction plays a crucial role in the initiation and progression of CVD, serving as a pivotal factor in the pathogenesis of cardiovascular, metabolic, and other related diseases. The regulation of endothelial dysfunction is influenced by various risk factors and intricate signaling pathways, which vary depending on the specific disease context. Despite numerous research efforts aimed at elucidating the mechanisms underlying endothelial dysfunction, the precise molecular pathways involved remain incompletely understood. This review elucidates recent research findings on the pathophysiological mechanisms involved in endothelial dysfunction, including nitric oxide availability, oxidative stress, and inflammation-mediated pathways. We also discuss the impact of endothelial dysfunction on various pathological conditions, including atherosclerosis, heart failure, diabetes, hypertension, chronic kidney disease, and neurodegenerative diseases. Furthermore, we summarize the traditional and novel potential biomarkers of endothelial dysfunction as well as pharmacological and nonpharmacological therapeutic strategies for endothelial protection and treatment for CVD and related complications. Consequently, this review is to improve understanding of emerging biomarkers and therapeutic approaches aimed at reducing the risk of developing CVD and associated complications, as well as mitigating endothelial dysfunction.

Angiotensin converting enzyme inhibitors and risk of lung cancer: A systematic review and meta-analysis

BACKGROUND

We performed a meta-analysis to determine whether a consistent relationship exists between the use of angiotensin converting enzyme inhibitors (ACEIs) and the risk of lung cancer. Accordingly, we summarized and reviewed previously published quantitative studies.

METHODS

Eligible studies with reference lists published before June 1st, 2019 were obtained from searching several databases. Random effects' models were used to summarize the overall estimate of the multivariate adjusted odds ratios (ORs) with 95% confidence intervals (CIs).

RESULTS

Thirteen observational studies involving 458,686 ACEI users were included in the analysis, Overall, pooled risk ratios indicate that ACEIs use was not a risk factor for lung cancer (RR 0.982, 95% C.I. 0.873 - 1.104; P = .76). There was significant heterogeneity between the studies (Q = 52.54; P < .001; I2 = 86.07). There was no significant association between ACEIs use and lung cancer in studies with over five years of ACEIs exposure (RR 0.95, 95% C.I. 0.75 - 1.20; P = .70); and ≤ 5years of exposure to ACEIs (RR 0.98, 95% C.I. 0.83 - 1.15; P = .77). There were no statistically significant differences in the pooled risk ratio obtained according to the study design (Q = 0.65; P = .723) and the comparator regimen (Q = 3.37; P = .19).

CONCLUSIONS

The use of ACEIs was not associated with an increased risk of lung cancer. Nevertheless, well-designed observational studies with different ethnic populations are still needed to evaluate the long-term (over 10 years) association between ACEIs use and lung cancer.

Endothelial Dysfunction and Its Clinical Implications

Endothelial dysfunction (ED) plays a substantial role in the pathogenesis of atherosclerosis and some other vascular diseases. ED has been demonstrated in patients with hypercholesterolemia, diabetes, smoking, hypertension, and in patients with atherosclerotic disease. Besides classical risk factors, ED is affected by chronic inflammatory diseases and acute infections, particularly viral diseases. Causes of ED include oxidative stress, inflammation, and shear stress, which decrease the bioavailability of nitric oxide. Markers of ED have been sought, particularly circulating markers. Using these tests, it is possible to evaluate the response to harmful effects of risk factors and the effects of treatment on vessel wall function. Endothelial dysfunction is significantly and directly correlated with the occurrence of cardiac events and the risk of cardiac events increase as ED worsens. Because endothelial function plays a central role in atherogenesis it became a therapeutic target. Endothelial dysfunction is reversible and its improvement may be achieved by elimination of risk factors, inhibitors of endothelium-derived contracting factors (angiotensin-converting enzyme), smoking cessation, lipid-lowering drugs, diet, and physical exercise. By reversing ED, it is possible to restore vascular function.

Splenic release of platelets contributes to increased circulating platelet size and inflammation after myocardial infarction

Acute myocardial infarction (AMI) is characterized by a rapid increase in circulating platelet size but the mechanism for this is unclear. Large platelets are hyperactive and associated with adverse clinical outcomes. We determined mean platelet volume (MPV) and platelet-monocyte conjugation (PMC) using blood samples from patients, and blood and the spleen from mice with AMI. We further measured changes in platelet size, PMC, cardiac and splenic contents of platelets and leucocyte infiltration into the mouse heart. In AMI patients, circulating MPV and PMC increased at 1-3 h post-MI and MPV returned to reference levels within 24 h after admission. In mice with MI, increases in platelet size and PMC became evident within 12 h and were sustained up to 72 h. Splenic platelets are bigger than circulating platelets in normal or infarct mice. At 24 h post-MI, splenic platelet storage was halved whereas cardiac platelets increased by 4-fold. Splenectomy attenuated all changes observed in the blood, reduced leucocyte and platelet accumulation in the infarct myocardium, limited infarct size and alleviated cardiac dilatation and dysfunction. AMI-induced elevated circulating levels of adenosine diphosphate and catecholamines in both human and the mouse, which may trigger splenic platelet release. Pharmacological inhibition of angiotensin-converting enzyme, β1-adrenergic receptor or platelet P2Y12 receptor reduced platelet abundance in the murine infarct myocardium albeit having diverse effects on platelet size and PMC. In conclusion, AMI evokes release of splenic platelets, which contributes to the increase in platelet size and PMC and facilitates myocardial accumulation of platelets and leucocytes, thereby promoting post-infarct inflammation.

Cardiovascular function and predictors of exercise capacity in patients with colorectal cancer

BACKGROUND

Patients with colorectal cancer (CRC) often present with dyspnea and fatigue. These are also frequent symptoms in patients with chronic heart failure (CHF).

OBJECTIVES

We hypothesized that similar patterns of cardiovascular perturbations are present in CRC and CHF.

METHODS

We prospectively studied 50 patients with CRC, 51 patients with CHF, and 51 control subjects. The CRC group was divided into 2 subgroups: patients who underwent chemotherapy (n = 26) and chemotherapy-naive patients (n = 24). We assessed exercise capacity (spiroergometry), cardiac function (echocardiography), heart rate variability (Holter electrocardiography), body composition (dual-energy x-ray absorptiometry), and blood parameters.

RESULTS

Compared with the control arm, the left ventricular ejection fraction (CRC group 59.4%; control group 62.5%) and exercise performance as assessed by peak oxygen consumption (peak VO2) (CRC group 21.8 ml/kg/min; control group 28.0 ml/kg/min) were significantly reduced in CRC patients (both p < 0.02). Markers of heart rate variability were markedly impaired in CRC patients compared with control subjects (all p < 0.008). Compared with the control group, the CRC group also showed reduced lean mass in the legs and higher levels of the endothelium-derived C-terminal-pro-endothelin-1 (both p < 0.02). Major determinants of cardiovascular function were impaired in chemotherapy-treated patients and in the chemotherapy-naive patients, particularly with regard to exercise capacity, left ventricular ejection fraction, lean mass, and heart rate variability (all p < 0.05 vs. control subjects).

CONCLUSIONS

Some aspects of cardiovascular function are impaired in patients with CRC. More importantly, our findings were evident independently of whether patients were undergoing chemotherapy.

Effect of Angiotensin-converting enzyme inhibitors and Angiotensin receptor antagonists in atherosclerosis prevention

Atherosclerosis is a highly complex biological process that has become the scourge of modern civilization. Endothelial dysfunction is the first step in the development of atherosclerosis. The renin-angiotensin-aldosterone system (RAAS) plays an important role in the development of endothelial dysfunction and atherosclerosis. Several studies have shown that in vitro blockade of the RAAS is associated with improvement in markers of endothelial dysfunction and inflammation. Many clinical trials have demonstrated a clear benefit of angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) manifested by a reduction of cardiovascular events. These findings suggest that ACEIs and ARBs can play an important role in prevention of atherosclerosis and in the delay of its progression. In this review we focus on the importance of RAAS blockade to prevent or delay progression of atherosclerosis and its impact on reduction of cardiovascular events.

Angiotensin-converting enzyme inhibition prevents the release of monocytes from their splenic reservoir in mice with myocardial infarction

RATIONALE

Monocytes recruited to ischemic myocardium originate from a reservoir in the spleen, and the release from their splenic niche relies on angiotensin (Ang) II signaling.

OBJECTIVE

Because monocytes are centrally involved in tissue repair after ischemia, we hypothesized that early angiotensin-converting enzyme (ACE) inhibitor therapy impacts healing after myocardial infarction partly via effects on monocyte traffic.

METHODS AND RESULTS

In a mouse model of permanent coronary ligation, enalapril arrested the release of monocytes from the splenic reservoir and consequently reduced their recruitment into the healing infarct by 45%, as quantified by flow cytometry of digested infarcts. Time-lapse intravital microscopy revealed that enalapril reduces monocyte motility in the spleen. In vitro migration assays and Western blotting showed that this was caused by reduced signaling through the Ang II type 1 receptor. We then studied the long-term consequences of blocked splenic monocyte release in atherosclerotic apolipoprotein (apo)E(-/-) mice, in which infarct healing is impaired because of excessive inflammation in the cardiac wound. Enalapril improved histologic healing biomarkers and reduced inflammation in infarcts measured by FMT-CT (fluorescence molecular tomography in conjunction with x-ray computed tomography) of proteolytic activity. ACE inhibition improved MRI-derived ejection fraction by 14% on day 21, despite initially comparable infarct size. In apoE(-/-) mice, ischemia/reperfusion injury resulted in larger infarct size and enhanced monocyte recruitment and was reversible by enalapril treatment. Splenectomy reproduced antiinflammatory effects of enalapril.

CONCLUSION

This study suggests that benefits of early ACE inhibition after myocardial infarction can partially be attributed to its potent antiinflammatory impact on the splenic monocyte reservoir.

Expression of vascular endothelial growth factor and receptor tyrosine kinases in cardiac ischemia/reperfusion injury

INTRODUCTION

Vascular endothelial growth factor (VEGF) expression is regulated by hypoxia and cytokines, including insulin-like growth factor (IGF)-1. We examined the influence of ischemia/reperfusion (I/R) on IGF-1, VEGF, fetal liver kinase (flk-1), fms-like tyrosine kinase-1 (flt-1), and laminin using an isolated hemoperfused working porcine heart model of acute ischemia (2 h) and reperfusion (4 h).

METHODS

Twenty-three porcine hearts were randomized into the following groups: five nonischemic control hearts (Group C), five I/R hearts with occlusion of the ramus circumflexus; three I/R hearts treated with quinaprilat, a potent angiotensin-converting enzyme (ACE) inhibitor (Group Q); five I/R hearts treated with angiotensin I (Group Ang I), and 5 I/R hearts treated with Ang I and quinaprilat (Group QA).

RESULTS

Compared to C, VEGF mRNA and protein contents were significantly increased in I/R and Ang I hearts. flk-1 and flt-1 were increased in I/R (2.2-/1.95-fold) and further elevated by Ang I (3.2-/3.4-fold) compared with C. Quinaprilat application attenuated the amount of VEGF significantly and of flk-1 slightly but not that of flt-1. In contrast, IGF-1 and IGF-1 receptor (IGF-1R) proteins were elevated in I/R hearts (3-/1.4-fold vs. C) and further increased in the presence of Q. These findings were accompanied by an elevation of laminin mRNA and protein levels. Moreover, we observed an increase in collagen Type IV and chondroitin sulfate content in I/R (2.9-/1.4-fold) and Ang I (3.5-/1.5-fold) hearts. Quinaprilat significantly reduced laminin and chondroitin sulfate proteins.

CONCLUSION

These data suggest that the VEGF/VEGF receptor and IGF-1-IGF-1R systems are activated by I/R. The benefits of ACE inhibition in attenuation of cardiac remodeling may be mediated by IGF-1.

Acute effects of renin-angiotensin system blockade on arterial function in hypertensive patients

The acute effects of the renin-angiotensin system (RAS) blockers may be important in some clinical settings. To assess the acute impact of such drugs on arterial function, we studied the effects of captopril 25 mg, quinapril 20 mg and telmisartan 80 mg on 100 hypertensive patients, according to a randomized, double-blind, placebo-controlled study. Central (aortic) blood pressure (BP) and augmentation index (AIx, a measure of wave reflections), as well as flow-mediated dilatation (FMD) of the brachial artery and forearm blood flow (FBF) (measures of conduit and resistance artery endothelial function, respectively), were evaluated before and 2 h after oral drug administration. Compared to placebo, captopril and quinapril decreased central systolic (by 7.5 mm Hg, P<0.05 and by 12.3 mm Hg, P<0.001) and diastolic BP (by 4.9 mm Hg, P<0.01 and by 8.4 mm Hg, P<0.001), whereas telmisartan had no significant effect (P=NS). Additionally, AIx was reduced after quinapril (absolute decrease of 7.2%, P<0.01) and marginally after captopril (decrease of 4.7%, P=0.07). Only quinapril led to a beneficial change of FMD (absolute increase of 2.7%, P<0.001). No treatment was related to significant changes of peak hyperaemic or 3-min hyperaemic FBF. In adjusted analyses, all the favourable alterations induced by quinapril were independent of potential confounding haemodynamic factors. Our data show that acute RAS inhibition with quinapril (20 mg) may be more beneficial in terms of arterial function and central haemodynamics compared to captopril (25 mg) or telmisartan (80 mg). Further studies are needed to investigate whether these acute arterial effects of quinapril are clinically significant.

Mechanisms of apoptosis after ischemia and reperfusion: role of the renin-angiotensin system

BACKGROUND

Apoptosis plays a key role in the pathogenesis of cardiac diseases. We examined the influence of the renin-angiotensin system (RAS) on different regulators of apoptosis using an isolated hemoperfused working porcine heart model of acute ischemia (2 h), followed by reperfusion (4 h).

METHODS AND RESULTS

23 porcine hearts were randomized to 5 groups: hemoperfused non-infarcted hearts (C), infarcted hearts (MI: R. circumflexus), infarcted hearts treated with quinaprilat (Q), infarcted hearts treated with angiotensin-I (Ang I), and infarcted hearts treated with angiotensin-I and quinaprilat (QA). Fas, Bax, bcl-2 and p53 proteins were increased in MI hearts and further elevated by Ang I. Quinaprilat reduced Bax and p53. Bcl-2 was elevated in Q and reduced in QA. An early upregulation of caspase-3 gene and protein expression was detected in MI and Ang I hearts compared to C. Q reduced caspase-3 gene expression, but had no effect on caspase-3 and Fas protein.

CONCLUSIONS

These data suggest that the RAS plays a pivotal role in cardiac apoptosis which is the early and predominant form of death in myocardial infarction. Ischemia/reperfusion induces programmed cell death via extrinsic and intrinsic pathways. Early treatment with quinaprilat attenuated cardiomyocyte apoptosis.

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.

Role of Angiotensin-Converting Enzyme Inhibitors in the Coronary Artery Bypass Patient

Angiotensin-converting enzyme inhibitors have been shown to prolong survival and decrease infarct size in patients after acute coronary syndromes. Now there is evidence to suggest that angiotensin-converting enzyme inhibition is beneficial in coronary artery bypass patients. This review will summarize the beneficial effects of angiotensin-converting enzyme inhibition in patients with ischemic heart disease and provide evidence to show that the routine use of angiotensin-converting enzyme inhibition in coronary artery bypass patients can improve clinical outcomes.

The use of angiotensin-converting enzyme inhibitors in patients undergoing coronary artery bypass graft surgery

Angiotensin-converting enzyme inhibitors have been shown to prolong survival, decrease infarct size, and improve ventricular function in patients who have congestive heart failure, and in those who have sustained a myocardial infarction. This review will summarize the evidence to show that angiotensin-converting enzyme inhibitors can also benefit patients undergoing coronary artery bypass graft surgery by minimizing perioperative ischemia, and reducing long-term cardiovascular events.

Does Off-Pump Revascularization Reduce Coronary Endothelial Dysfunction?

BACKGROUND

Off-pump coronary revascularization (OPCAB) has been shown to reduce markers of acute inflammation but its effect on coronary endothelial function is unknown. This experimental study sought to determine whether OPCAB reduces endothelial dysfunction, compared to standard cardiopulmonary bypass (CPB) with and without the anticomplement agent soluble complement receptor-1 (sCR(1)).

METHODS

In 10 pigs, OPCAB was simulated by snaring the left anterior descending (LAD) artery for 15 minutes followed by 3 hours of reperfusion. On-pump revascularization was simulated in 20 pigs by 15 minutes of LAD occlusion on CPB with cold blood cardioplegic arrest followed by 3 hours of reperfusion. Ten of these animals received sCR(1) (10 mg/kg) prior to CPB. Inflammatory response was monitored by percent (%) lung water increase, wall motion scores (WMS) with transthoracic echocardiography where 4 = normal to -1 = dyskinesia, and endothelial function in the distal LAD with bradykinin-induced coronary artery relaxation using organ chamber methodology.

RESULTS

OPCAB had no effect on lung edema (% increase = 1.7 +/- 1.4 OPCAB vs. 3.4 +/- 0.5 CPB vs. 2.3 +/- 0.9 CPB + sCR(1)) and failed to prevent wall motion changes (WMS = 2.65 +/- 0.08 OPCAB vs. 2.70 +/- 0.04 CPB vs. 3.10 +/- 0.07* CPB + sCR(1), *p < 0.01) and coronary endothelial dysfunction (% relaxation = 41 +/- 9 OPCAB vs. 40 +/- 9 CPB vs. 78 +/- 8** CPB + sCR(1), **p < 0.001), which was best preserved with sCR(1).

CONCLUSIONS

This study suggests that agents which directly inhibit complement activation such as sCR(1) are more important in preventing endothelial dysfunction during coronary revascularization than merely avoiding CPB.

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.

Long Term Angiotensin Converting Enzyme-inhibition in Patients after Coronary Artery Bypass Grafting Reduces Levels of Soluble Intercellular Cell Adhesion Molecule-1

OBJECTIVE

to examine the effect of angiotensin converting enzyme inhibition (ACEI) on soluble intercellular adhesion molecule 1 (sICAM-1) and C-reactive protein (CRP) in patients requiring coronary artery bypass grafting (CABG).

METHOD

subgroup analysis of 42 patients randomised to Quinapril (40 mg daily determined) and 45 to placebo. sICAM-1 and CRP were > or = 4 weeks before and 1 year after surgery.

RESULTS

there was no difference in sICAM-1 at baseline (142.2 microg/L vs 136.6 microg/L). There was significant reduction in s-ICAM-1 in patients receiving quinapril (142.2+/-10.8 microg/L vs 125.6+/-9.4 microg/L, p<0.05) but not placebo (136.6+/-10.2 microg/L vs 131.2+/-11.7 microg/L, p=NS). Levels of C-reactive protein remained unchanged in both groups (3.70+/-0.85 vs 2.73+/-0.32 mg/L, 2.85+/-0.48 vs 3.16+/-0.50 mg/L).

CONCLUSIONS

ACEI reduces sICAM-1 in patients undergoing CABG. The benefits of ACEI may partly be due to a reduction of the vascular inflammatory response.

Quinaprilat reduces myocardial infarct size involving nitric oxide production and mitochondrial KATP channel in rabbits

This study examined whether quinaprilat, an angiotensin-converting enzyme inhibitor, reduces the infarct size, and investigated the mechanisms for its infarct size-reducing effect, in rabbits. Japanese white rabbits underwent 30 min of ischemia and 48 h of reperfusion. Quinaprilat (100 microg/kg/h or 300 microg/kg/h for 70 min, IV) was administered 20 min before ischemia with or without pretreatment with Nomega-nitro-l-arginine methyl ester (l-NAME) (10 mg/kg, IV, a nitric oxide synthase inhibitor), 5-hydroxydecanoic acid sodium salt (5-HD) or posttreatment with 5-HD (5 mg/kg, IV, a mitochondrial KATP channel blocker). The area at risk as a percentage of the left ventricle was determined by Evans blue dye and the infarct size was determined as a percent of the area at risk by triphenyl tetrazolium chloride staining. Using a microdialysis technique, myocardial interstitial levels of 2,5-dihydroxybenzoic acid (2,5-DHBA), an indicator of hydroxyl radicals, and NOx, an indicator of nitric oxide, were measured before, during, and after 30 min of ischemia. Quinaprilat significantly reduced the infarct size in a dose-dependent manner (30.1 +/- 3%, n = 10, and 27.6 +/- 2%, n = 7, respectively) compared with the control (46.5 +/- 4%, n = 10). The infarct size-reducing effect of quinaprilat was completely blocked by pretreatment with l-NAME (43.8 +/- 2%, n = 8) and 5-HD (50.1 +/- 3%, n = 8) and posttreatment with 5-HD (50.3 +/- 2%, n = 8), respectively. Quinaprilat did not affect the myocardial interstitial 2,5-DHBA level but significantly increased the NOx level during ischemia and reperfusion. Quinaprilat reduces myocardial infarct size involving NO production and mitochondrial KATP channels in rabbits without collateral circulation.

High levels of circulating endothelial microparticles in patients with acute coronary syndromes

BACKGROUND

Endothelial injury plays a critical role in coronary artery disease (CAD), but the assessment of this injury has been problematical. Recently, it has been shown in vitro that endothelial cells (ECs) release endothelial microparticles (EMPs) on activation or apoptosis and that an assay of EMPs can provide useful information on EC status in patients with thrombotic disorders. This study is aimed at assessing possible correlations between EMPs, which are markers of endothelial injury, and clinical subgroups of patients with CAD.

METHODS

A prospective, case-controlled study was conducted on 84 patients with CAD and 42 control subjects to investigate EMP profiles. Included were 64 patients with acute coronary syndromes ([ACS], 38 with myocardial infarction [MI] and 26 with unstable angina [UA]) and 20 patients with stable angina (SA). EMPs in platelet-poor plasma were measured flow cytometrically with combinations of fluorescent antibodies (anti-CD31, -51, -42), allowing distinction of EMPs from platelet microparticles (PMPs). Clinical subgroups of patients were correlated with EMP and PMP levels in blood.

RESULTS

Two species of EMPs (CD31+ and CD51+) were evaluated. Both were significantly higher in patients with CAD than in control subjects. CD31+ EMP was higher in ACS than SA. Among patients with first MI, CD31+ EMP was higher in patients with MI than in patients with UA and was significantly higher than in patients with recurring MI. CD51+ EMP did not discriminate ACS from SA. A simultaneous assay of PMP showed correlation between EMPs and PMPs. However, PMPs did not discriminate patients with SA from control subjects.

CONCLUSIONS

EMP assay appears promising for assessing EC injury in CAD.

Role of the bradykinin B2 receptor for the local and systemic inflammatory response that follows severe reperfusion injury

1. Bradykinin (BK) appears to play an important role in the development and maintenance of inflammation. Here, we assessed the role of the BK B(2) receptor for the injuries that occur after ischemia and reperfusion (I/R) of the territory irrigated by the superior mesenteric artery. 2. Tissue (lung and duodenum) kallikrein activity increased after ischemia with greater enhancement after reperfusion. A selective inhibitor of tissue kallikrein, Phenylacetyl-Phe-Ser-Arg-N-(2,3-dinitrophenyl)-ethylenediamine (TKI, 0.001-10 mg ml(-1)), inhibited kallikrein activity in a concentration-dependent manner in vitro. In vivo, pretreatment with TKI (30 mg kg(-1)) prevented the extravasation of plasma and the recruitment of neutrophils. 3. Similarly, the bradykinin B(2) receptor antagonists, HOE 140 (0.01-1.0 mg kg(-1)) or FR173657 (10.0 mg kg(-1)), inhibited reperfusion-induced increases in vascular permeability and the recruitment of neutrophils in the intestine and lungs. 4. In a model of more severe I/R injury, HOE 140 (1.0 mg kg(-1)) inhibited the increase in vascular permeability, neutrophil recruitment, haemorrhage and tissue pathology. Furthermore, HOE 140 significantly inhibited the elevations of TNF-alpha in tissue and serum and partially prevented lethality. This was associated with an increase in the concentrations of IL-10 in tissue and serum. 5. Thus, our results demonstrate that, following intestinal I/R injury, there is an increase in tissue kallikrein activity and activation of BK B(2) receptors. B(2) receptor activation is essential for the development of inflammatory tissue injury and lethality. These results contrast with those of others showing that BK mostly exerts a protective role during I/R injury.

Left ventricular support by catheter-mounted axial flow pump reduces infarct size

OBJECTIVES

We sought to investigate the effect of a catheter-mounted microaxial blood pump (Impella, Aachen, Germany) on myocardial infarct size.

BACKGROUND

The small rotary blood pump Impella provides unloading of the left ventricle and is introducible via the femoral artery.

METHODS

Myocardial infarction was induced by occlusion of major branches of the left anterior descending coronary artery for 60 min followed by 120 min of reperfusion in 26 sheep. The animals were allocated to four groups: group 1 had no support; group 2 was fully supported with the pump during ischemia and reperfusion; group 3 was supported during reperfusion only; and group 4 was partially supported during reperfusion. Infarct size, hemodynamics, myocardial oxygen consumption, lactate extraction, and myocardial flow were analyzed.

RESULTS

Infarct size was significantly reduced in the pump-supported animals (percent area at risk in group 1: 67.2 +/- 4.6%; group 2: 18.1 +/- 10%; group 3: 41.6 +/- 5.8%; group 4: 54 +/- 8%; p = 0.00001). The pump produced 4.1 +/- 0.1 l/min at full support and 2.4 +/- 0.1 l/min at partial support. The pump significantly increased the diastolic and mean blood pressures (groups 2, 3, and 4) and significantly decreased the left ventricular end-diastolic pressure (groups 2 and 3). During ischemia, myocardial flow was not influenced by pump support. At reperfusion, the fully supported group had significantly higher myocardial flow. Pump support reduced myocardial oxygen consumption significantly, and this reduction correlates strongly with the reduction in infarct size (r = 0.9).

CONCLUSIONS

Support by a microaxial blood pump reduces myocardial oxygen consumption during ischemia and reperfusion and leads to a reduction of infarct size. This reduction in infarct size correlates with the degree of unloading during reperfusion.

New strategies for prevention of ischemic stroke: the LIFE study

New strategies to lower the risk of stroke among high-risk persons are being developed. Therapies such as cholesterol-lowering medications and newer antihypertensive agents appear to complement traditional antithrombotic drugs and surgical procedures. Of particular interest is the use of the newer angiotensin-converting enzyme (ACE) inhibitors, which appear to have an effect on stabilizing the vascular endothelium. The Losartan Intervention For Endpoint (LIFE) reduction in hypertension study provides additional data to support the use of the ACE inhibitors to lower the risk of stroke among patients with hypertension and vascular diseases.

Pretreatment with angiotensin-converting enzyme inhibitors attenuates ischemia-reperfusion injury

BACKGROUND

The Heart Outcomes Prevention Evaluation (HOPE) trial demonstrated that ischemic events are decreased in patients receiving angiotensin-converting enzyme (ACE) inhibitors. This study sought to determine whether pretreatment with ACE inhibitors would attentuate ischemic injury during surgical revascularization of ischemic myocardium.

METHODS

In a porcine model, the second and third diagonal vessels were occluded for 90 minutes, followed by 45 minutes of cardioplegic arrest, and 180 minutes of reperfusion. Ten pigs received quinapril (20 mg p.o. q.d.) for 7 days prior to surgery; 10 others received no-ACE inhibitors.

RESULTS

Quinapril-treated animals required less cardioversions for ventricular arrhythmias (1.58 +/- 0.40 vs 2.77 +/- 0.22; p < 0.05), had higher wall motion scores assessed by two-dimensional echocardiography (4 = normal to -1 = dyskinesia; 2.11 +/- 0.10 vs 1.50 +/- 0.07; p < 0.05), more complete coronary artery endothelial relaxation to bradykinin (45% +/- 3% vs 7% +/- 4%; p < 0.005), and lower infarct size (24.0% +/- 3.0% vs 40.0% +/- 1.7%; p < 0.0001).

CONCLUSIONS

ACE inhibition prior to coronary revascularization enhances myocardial protection by decreasing ventricular irritability, improving regional wall motion, lowering infarct size, and preserving endothelial function.