Bradykinin improves left ventricular diastolic function under long-term angiotensin-converting enzyme inhibition in heart failure

Transcriptome analysis of a dog model of congestive heart failure shows that collagen-related 2-oxoglutarate-dependent dioxygenases contribute to heart failure

Fibrosis is an important pathological mechanism in heart failure (HF) and is associated with poor prognosis. We analyzed fibrosis in HF patients using transcriptomic data. Genes differentially expressed between normal control and congestive HF (CHF) dogs included P3H1, P3H2, P3H4, P4HA2, PLOD1 and PLOD3, which belong to the 2-oxoglutarate-dependent dioxygenases (2OGD) superfamily that stabilizes collagen during fibrosis. Quantitative polymerase chain reaction analysis demonstrated 2OGD gene expression was increased in CHF samples compared with normal left ventricle (LV) samples. 2OGD gene expression was repressed in angiotensin converting enzyme inhibitor-treated samples. These genes, activated the hydroxylation of proline or lysin residues of procollagen mediated by 2-oxoglutaric acid and O_2, produce succinic acid and CO₂. Metabolic analysis demonstrated the concentration of succinic acid was significantly increased in CHF samples compared with normal LV samples. Fibrosis was induced in human cardiac fibroblasts by TGF-ß1 treatment. After treatment, the gene and protein expressions of 2OGD, the concentration of succinic acid, and the oxygen consumption rate were increased compared with no treatment. This is the first study to show that collagen-related 2OGD genes contribute to HF during the induction of fibrosis and might be potential therapeutic targets for fibrosis and HF.

Endothelial dysfunction: developmental mechanisms and therapeutic strategies

Introduction: Every year the importance of the normal functioning of the endothelial layer of the vascular wall in maintaining the health of the body becomes more and more obvious.

The physiological role of the endothelium: The endothelium is a metabolically active organ actively involved in the regulation of hemostasis, modulation of inflammation, maintenance of hemovascular homeostasis, regulation of angiogenesis, vascular tone, and permeability.

Risk factors for the development of endothelial dysfunction: Currently, insufficient bioavailability of nitric oxide is considered the most significant risk factor for endothelial dysfunction.

Mechanisms of development of endothelial dysfunction: The genesis of endothelial dysfunction is a multifactorial process. Among various complex mechanisms, this review examines oxidative stress, inflammation, hyperglycemia, vitamin D deficiency, dyslipidemia, excess visceral fat, hyperhomocysteinemia, hyperuricemia, as well as primary genetic defect of endotheliocytes, as the most common causes in the population underlying the development of endothelial dysfunction.

Markers of endothelial dysfunction in various diseases: This article discusses the main biomarkers of endothelial dysfunction currently used, as well as promising biomarkers in the future for laboratory diagnosis of this pathology.

Therapeutic strategies: Therapeutic approaches to the endothelium in order to prevent or reduce a degree of damage to the vascular wall are briefly described.

Conclusion: Endothelial dysfunction is a typical pathological process involved in the pathogenesis of many diseases. Thus, pharmacological agents with endothelioprotective properties can provide more therapeutic benefits than a drug without such an effect.

The vital role for nitric oxide in intraocular pressure homeostasis

Catalyzed by endothelial nitric oxide (NO) synthase (eNOS) activity, NO is a gaseous signaling molecule maintaining endothelial and cardiovascular homeostasis. Principally, NO regulates the contractility of vascular smooth muscle cells and permeability of endothelial cells in response to either biochemical or biomechanical cues. In the conventional outflow pathway of the eye, the smooth muscle-like trabecular meshwork (TM) cells and Schlemm's canal (SC) endothelium control aqueous humor outflow resistance, and therefore intraocular pressure (IOP). The mechanisms by which outflow resistance is regulated are complicated, but NO appears to be a key player as enhancement or inhibition of NO signaling dramatically affects outflow function; and polymorphisms in NOS3, the gene that encodes eNOS modifies the relation between various environmental exposures and glaucoma. Based upon a comprehensive review of past foundational studies, we present a model whereby NO controls a feedback signaling loop in the conventional outflow pathway that is sensitive to changes in IOP and its oscillations. Thus, upon IOP elevation, the outflow pathway tissues distend, and the SC lumen narrows resulting in increased SC endothelial shear stress and stretch. In response, SC cells upregulate the production of NO, relaxing neighboring TM cells and increasing permeability of SC's inner wall. These IOP-dependent changes in the outflow pathway tissues reduce the resistance to aqueous humor drainage and lower IOP, which, in turn, diminishes the biomechanical signaling on SC. Similar to cardiovascular pathogenesis, dysregulation of the eNOS/NO system leads to dysfunctional outflow regulation and ocular hypertension, eventually resulting in primary open-angle glaucoma.

Angioedema: a rare and sometimes delayed side effect of angiotensin-converting enzyme inhibitors

The effects of angiotensin converting enzyme (ACE) inhibitors result from the inhibition of the ACE (kininase II) to ultimately influence both the renin-angiotensin system and the degradation of the bradykinin (BK) metabolism. ACE inhibitors block the degradation of BK and substance P by ACE. In addition, an active metabolite of BK (Des-Arg9-BK) is catalysed by kininase I and its degradation is controlled in part by the conversion enzyme. These molecules have been associated with increased plasma extravasation associated with ACE inhibitors. ACE inhibitors are the leading cause of drug-induced Angioedema (AE). Symptoms of AE mainly occur after the first month of treatment by ACE. However, very late onset cases, sometimes after several years of stable therapy, are also described in the literature. It has been observed that patients previously stable under ACE inhibitor will most likely develop AE soon after the addition of another medication, including the combination of aspirin or non-steroid anti-inflammatory drugs with ACE inhibitor which has proved to be the most common cause, accounting for close to 50% of all AE cases related to ACE inhibitors. This side effect of ACE inhibitors, sometimes very late and rare, deserves to be recalled.

Blood pressure normalization via pharmacotherapy improves cutaneous microvascular function through NO-dependent and NO-independent mechanisms

Hypertension is associated with endothelial dysfunction and vascular remodeling.

OBJECTIVE

To assess effects of antihypertensive pharmacotherapy on eNOS- and iNOS-dependent mechanisms and maximal vasodilator capacity in the cutaneous microvasculature.

METHODS

Intradermal microdialysis fibers were placed in 15 normotensive (SBP 111±2 mm Hg), 12 unmedicated hypertensive (SBP 142±2 mm Hg), and 12 medicated hypertensive (SBP 120±2 mm Hg) subjects. Treatments were control, iNOS-inhibited (1400w), and NOS-inhibited (l-NAME). Red cell flux, measured during local heating (42°C) and ACh dose-response protocols, was normalized to CVC (flux MAP^-1 ) and a percentage of maximal vasodilation (%CVC_max ).

RESULTS

Compared to normotensives, ACh-mediated vasodilation was attenuated in the hypertensive (P<.001), but not in medicated subjects (P=.83). NOS inhibition attenuated ACh-mediated vasodilation in normotensives compared to hypertensive (P<.001) and medicated (P<.001) subjects. With iNOS inhibition, there was no difference in ACh-mediated vasodilation between groups. Compared to the normotensives, local heat-induced vasodilation was attenuated in the hypertensives (P<.001), but iNOS inhibition augmented vasodilation in the hypertensives so this attenuation was abolished (P=.31). Compared to normotensives, maximal vasodilator capacity was reduced in the hypertensive (P=.014) and medicated subjects (P=.004).

CONCLUSIONS

In the cutaneous microvasculature, antihypertensive pharmacotherapy improved endothelial function through NO-dependent and NO-independent mechanisms, but did not improve maximal vasodilator capacity.

A comparison study of the echocardiographic changes in hypertensive patients treated with telmisartan vs. enalapril

BACKGROUND

Hypertension-induced cardiac dysfunction is variable among different anti-hypertensive medications. This study compares the effects of telmisartan and enalapril on echocardiographic parameters in hypertensive patients.

MATERIALS AND METHODS

This was a randomised single blinded study. Eighty hypertensive patients were included in this study and they were randomly allocated into two study groups: Group 1 included 40 patients who took telmisartan 80mg once daily for six months. Group 2 included 40 patients who took enalapril, 20mg once daily for six months. An additional 40 healthy participants were enrolled in the study as controls (Group 3). Baseline echocardiographic scan was done at the start of the study and after 6 months of treatment including assessment of left ventricular systolic and diastolic functions with assessment of left ventricular mass index, in addition to measurements of blood pressure, heart rate and double product.

RESULTS

Both group 1 and group 2 (telmisartan and enalapril groups respectively) showed comparable statistically significant improvement in the diastolic functional parameters (P<0.010), while both medications didn't demonstrate changes in the systolic functional parameters. Furthermore, telmisartan was significantly effective in reducing the interventricular septal thickness and left ventricular mass index (P<0.010).

CONCLUSIONS

Both drugs interfere with renin-angiotensin aldosterone system, protecting the myocardium from high blood pressure. Findings from our study provide key results for physicians in deciding the appropriate antihypertensive drug for each patient depending based on the patient's intolerability for either medication.

Vascular endothelial dysfunction and pharmacological treatment

The endothelium exerts multiple actions involving regulation of vascular permeability and tone, coagulation and fibrinolysis, inflammatory and immunological reactions and cell growth. Alterations of one or more such actions may cause vascular endothelial dysfunction. Different risk factors such as hypercholesterolemia, homocystinemia, hyperglycemia, hypertension, smoking, inflammation, and aging contribute to the development of endothelial dysfunction. Mechanisms underlying endothelial dysfunction are multiple, including impaired endothelium-derived vasodilators, enhanced endothelium-derived vasoconstrictors, over production of reactive oxygen species and reactive nitrogen species, activation of inflammatory and immune reactions, and imbalance of coagulation and fibrinolysis. Endothelial dysfunction occurs in many cardiovascular diseases, which involves different mechanisms, depending on specific risk factors affecting the disease. Among these mechanisms, a reduction in nitric oxide (NO) bioavailability plays a central role in the development of endothelial dysfunction because NO exerts diverse physiological actions, including vasodilation, anti-inflammation, antiplatelet, antiproliferation and antimigration. Experimental and clinical studies have demonstrated that a variety of currently used or investigational drugs, such as angiotensin-converting enzyme inhibitors, angiotensin AT1 receptors blockers, angiotensin-(1-7), antioxidants, beta-blockers, calcium channel blockers, endothelial NO synthase enhancers, phosphodiesterase 5 inhibitors, sphingosine-1-phosphate and statins, exert endothelial protective effects. Due to the difference in mechanisms of action, these drugs need to be used according to specific mechanisms underlying endothelial dysfunction of the disease.

Left ventricle structural remodelling in the prediabetic Goto-Kakizaki rat

This study tested the hypothesis that experimental prediabetes can elicit structural remodelling in the left ventricle (LV). Left ventricles isolated from 8-week-old male Goto-Kakizaki (GK) rats and age-matched male Wistar control rats were used to assess remodelling changes and underlying transforming growth factor β1 (TGFβ1) activity, prohypertrophic Akt-p70S6K1 signalling and gene expression profile of the extracellular matrix (ECM) using histological, immunohistochemical, immunoblotting and quantitative gene expression analyses. Prediabetes in GK rats was confirmed by impaired glucose tolerance and modestly elevated fasting blood glucose. Left ventricle remodelling in the GK rat presented with marked hypertrophy of cardiomyocytes and increased ECM deposition that together translated into increased heart size in the absence of ultrastructural changes or fibre disarray. Molecular derangements underlying this phenotype included recapitulation of the fetal gene phenotype markers B-type natriuretic peptide and α-skeletal muscle actin, activation of the Akt-p70S6K1 pathway and altered gene expression profile of key components (collagen 1α and fibronectin) and modulators of the ECM (matrix metalloproteinases 2 and 9 and connective tissue growth factor). These changes were correlated with parallel findings of increased TGFβ1 transcription and activation in the LV and elevated active TGFβ1 in plasma of GK rats compared with control animals (Student's t test, P < 0.05 versus age-matched Wistar control animals for all parameters). This is the first report to describe LV structural remodelling in experimental prediabetes. The results suggest that ventricular decompensation pathognomonic of advanced diabetic cardiomyopathy may have possible origins in profibrotic and prohypertrophic mechanisms triggered before the onset of type 2 diabetes mellitus.

Angiotensin converting enzyme inhibitor induced angio-oedema: a review of the pathophysiology and risk factors

Angio-oedema (AE) is a known adverse effect of angiotensin converting enzyme inhibitor (ACE-I) therapy. Over the past several decades, evidence of failure to diagnose this important and potentially fatal reaction is commonly found in the literature. Because this reaction is often seen first in the primary care setting, a review was undertaken to analyse and document the keys to both diagnostic criteria as well as to investigate potential risk factors for ACE-I AE occurrence. A general review of published literature was conducted through Medline, EMBASE, and the Cochrane Database, targeting ACE-I-related AE pathomechanism, diagnosis, epidemiology, risk factors, and clinical decision making and treatment. The incidence and severity of AE appears to be on the rise and there is evidence of considerable delay in diagnosis contributing to significant morbidity and mortality for patients. The mechanism of AE due to ACE-I drugs is not fully understood, but some genomic and metabolomic information has been correlated. Additional epidemiologic data and clinical treatment outcome predictors have been evaluated, creating a basis for future work on the development of clinical prediction tools to aid in risk identification and diagnostic differentiation. Accurate recognition of AE by the primary care provider is essential to limit the rising morbidity associated with ACE-I treatment-related AE. Research findings on the phenotypic indicators relevant to this group of patients as well as basic research into the pathomechanism of AE are available, and should be used in the construction of better risk analysis and clinical diagnostic tools for ACE-I AE.

Simvastatin reverses cardiac hypertrophy caused by disruption of the bradykinin 2 receptor

Bradykinin 2 receptor (B2R) deficiency predisposes to cardiac hypertrophy and hypertension. The pathways mediating these effects are not known. Two-month-old B2R knockout (KO) and wild-type (WT) mice were assigned to 4 treatment groups (n = 12-14/group): control (vehicle); nitro-L-arginine methyl ester (L-NAME) an NO synthase inhibitor; simvastatin (SIM), an NO synthase activator; and SIM+L-NAME. Serial echocardiography was performed and blood pressure (BP) at 6 weeks was recorded using a micromanometer. Myocardial eNOS and mitogen-activated protein kinase (MAPK, including ERK, p38, and JNK) protein expression were measured. Results showed that (i) B2RKO mice had significantly lower ejection fraction than did WT mice (61% +/- 1% vs. 73% +/- 1%), lower myocardial eNOS and phospho-eNOS, normal systolic BP, and higher LV mass, phospho-p38, and JNK; (ii) L-NAME increased systolic BP in KO mice (117 +/- 19 mm Hg) but not in WT mice and exacerbated LV hypertrophy and dysfunction; and (iii) in KO mice, SIM decreased hypertrophy, p38, and JNK, improved function, increased capillary eNOS and phospho-eNOS, and prevented L-NAME-induced LV hypertrophy without lowering BP. We conclude that disruption of the B2R causes maladaptive cardiac hypertrophy with myocardial eNOS downregulation and MAPK upregulation. SIM reverses these abnormalities and prevents the development of primary cardiac hypertrophy as well as hypertrophy secondary to L-NAME-induced hypertension.

Modulation of the tissue reninangiotensin-aldosterone system in dogs with chronic mild regurgitation through the mitral valve

OBJECTIVE

To investigate whether the tissue and plasma renin-angiotensin-aldosterone system (RAAS) is activated in dogs with mild regurgitation through the mitral valve and determine the contribution of chymase and angiotensin-converting enzyme (ACE) to the activation of the RAAS and potential production of angiotensin II during the chronic stage of mild mitral valve regurgitation.

ANIMALS

5 Beagles with experimentally induced mild mitral valve regurgitation and 6 clinically normal (control) Beagles.

PROCEDURES

Tissue ACE and chymase-like activities and plasma RAAS were measured and the RAAS evaluated approximately 1,000 days after experimental induction of mitral valve regurgitation in the 5 dogs.

RESULTS

Dogs with experimentally induced mitral valve regurgitation did not have clinical signs of the condition, although echocardiography revealed substantial eccentric hyper- trophy. On the basis of these findings, dogs with mitral valve regurgitation were classified as International Small Animal Cardiac Health Council class Ib. Plasma activity of renin and plasma concentrations of angiotensin I, angiotensin II, and aldosterone were not significantly different between dogs with mitral valve regurgitation and clinically normal dogs. Tissue ACE activity was significantly increased and chymase-like activity significantly decreased in dogs with mitral valve regurgitation, compared with values in clinically normal dogs.

CONCLUSIONS AND CLINICAL RELEVANCE

The tissue RAAS was modulated without changes in the plasma RAAS in dogs with mild mitral valve regurgitation during the chronic stage of the condition. An ACE-dependent pathway may be a major route for production of angiotensin II during this stage of the condition.

Expression of interferon-gamma and interleukin-4 production in CD4+ T cells in patients with chronic heart failure

The prevalence of inflammation is high among patients with chronic heart failure (CHF). Reduced ejection fraction was associated with frequency of CD4(+) T cells of leukocytes. Therefore, we investigated inflammatory cytokines of expression markers in CD4(+) T cells in patients with CHF. Blood samples were obtained from 103 patients with CHF, from 83 patients with stable angina (SA), and from 57 controls. Interferon-gamma (IFN-gamma)-positive CD4(+) T cells and interleukin-4 (IL-4)-positive CD4(+) T cells were analyzed using 3-color flow cytometry. The frequency (%) of IFN-gamma-positive CD4(+) T cells increased in patients with CHF compared with those with SA and controls (CHF: 28.3 +/- 13.8, SA: 23.50 +/- 10.38, controls: 19.00 +/- 7.45, P < 0.001). There was no significant difference in the frequency of IL-4-positive CD4(+) T cells among the three groups. The frequencies of CD4(+) T cells that stained for IFN-gamma decreased from 32.37% +/- 16.40% on admission to 26.91% +/- 12.53% after 2 weeks in 26 patients with CHF. B-type natriuretic peptide (pg/ml) and high-sensitivity C-reactive protein (mg/dl) levels decreased from 251.7 +/- 150.4 and 0.64 +/- 0.78 on admission to 208.2 +/- 166.4 and 0.36 +/- 0.34 after 2 weeks in the 26 patients with CHF. We have demonstrated expression of IFN-gamma production of CD4(+) T cells during CHF. Prevention of unwanted T cell activation could represent a new target in the treatment of CHF.

Proteomic analysis reveals significant alternations of cardiac small heat shock protein expression in congestive heart failure

BACKGROUND

Because congestive heart failure (CHF) is a complex syndrome with many different underlying mechanisms of worsening of heart function, it is important to recognize the global alternations in protein expression associated with the processes of CHF.

METHODS AND RESULTS

The purpose of our study was to use a proteomic approach to investigate global alternations in protein expression in tachycardia induced CHF dogs. We compared the 2-dimensional electrophoresis protein patterns of left ventricular samples from the normal with those from failing myocardium. Differentially expressed cardiac proteins showed approximately 500 cardiac protein spots. A total of 20 spots (14 increased, 6 decreased) was altered in CHF, whereas the more distinguishably increased spots in CHF were identified by using mass spectrometry as alpha B crystallin, heat shock protein (HSP) 27, and HSP20, which maintain both the morphologic and functional integrity of the cardiomyocytes and increase tolerance against various types of stress. Because phosphorylation is one of the most important posttranslational modifications, we evaluated whether or not the overexpressed small HSPs were phosphorylated in CHF. Phosphoprotein staining and Western blotting demonstrated that the phosphorylation of alpha B crystallin at serine (Ser)-59 site and of HSP27 at both Ser-78 and Ser-82 sites increased in CHF.

CONCLUSION

Proteomics studies can provide new insights into molecular mechanisms in CHF and phosphorylated small HSPs may be involved in preventing cardiac dysfunction.

Critical role of bradykinin-eNOS and oxidative stress-LOX-1 pathway in cardiovascular remodeling under chronic angiotensin-converting enzyme inhibition

To elucidate the molecular mechanisms of the cardioprotective effect of angiotensin-converting enzyme (ACE) inhibitors, we evaluated whether the effect of quinapril involved in bradykinin-endothelial nitric oxide synthase (eNOS) and oxidative stress-lectin-like oxidized LDL receptor-1 (LOX-1) pathway. Dahl salt-sensitive hypertensive (DS) rats were fed a diet containing 8% NaCl and treated with one of the following drug combinations for 5 weeks, from 6 weeks of age to left ventricular hypertrophy stage (11 weeks): vehicle; quinapril; quinapril plus the bradykinin B2 receptor antagonist FR172357; the NAD(P)H oxidase inhibitor apocynin; or quinapril plus apocynin. eNOS expression, which was decreased in hypertrophy stage, was significantly increased by quinapril and/or apocynin, but not by quinapril plus FR172357. Upregulated expression of NAD(P)H oxidase p22phox, p47phox, gp91phox and LOX-1 was significantly decreased by quinapril to a similar degree as after treatment with apocynin, but not by quinapril plus FR172357. Quinapril and/or apocynin treatment effectively ameliorated left ventricular weight and vascular changes such as increase in medial thickness and perivascular fibrosis and suppressed expression of transforming growth factor-beta1, type I collagen and fibronectin mRNA, but not that of quinapril plus FR172357. These results suggest that the ACE inhibitor quinapril may have cardioprotective effects in this model of hypertension mediated at least in part through effects on the bradykinin-eNOS and oxidative stress-LOX-1 pathway.

Cardioprotective mechanisms of the kallikrein-kinin system in diabetic cardiopathy

PURPOSE OF REVIEW

Multiple pathogenic mechanisms contribute to the development of diabetic cardiopathy, including intramyocardial inflammation, cardiac fibrosis, abnormal intracellular Ca handling, microangiopathy and endothelial dysfunction. Moreover, the cardiac kallikrein-kinin system is thought to be altered under diabetic conditions and an improvement of this peptide system, e.g. by gene therapeutic approaches, has also been associated with an amelioration of the diabetic heart. In this review, we will discuss the hypothesis that the stimulation of the kallikrein-kinin system could be a promising target for the treatment of diabetic cardiopathy.

RECENT FINDINGS

The kallikrein-kinin system has cardioprotective properties, which may be particularly important under diabetic conditions. For example, its potential for endothelium-dependent vasodilation, and for improvement of glucose transport and utilization, make bradykinin an important mediator for reducing the consequences of diabetes-related oxidative stress on both the myocardium and vessels.

SUMMARY

The different synergistic cardioprotective effects of the kallikrein-kinin system in the diabetic heart suggest that the stimulation of the kallikrein-kinin system might open new avenues for the treatment of diabetic cardiopathy.

Effect of quinapril or losartan alone and in combination on left ventricular systolic and diastolic functions in asymptomatic patients with diabetic autonomic neuropathy

OBJECTIVE

To investigate the effect of angiotensin converting enzyme inhibition (ACE-I) or angiotensin receptor blockade (ARB), and their combination, on both diabetic autonomic neuropathy (DAN) and left ventricular (LV) diastolic dysfunction (LVDD) in asymptomatic patients with diabetes mellitus (DM).

MATERIALS AND METHODS

Sixty-two patients (34 women) with long-term DM (24 with Type 1) and DAN, aged 51.7+/-13.9 years, free of coronary artery disease (CAD) or arterial hypertension (HT) at baseline, were studied for a 12-month period. Diagnosis of DAN was established if two or more of the standard cardiovascular reflex tests (CRT) were abnormal. Patients were randomly allocated to quinapril (20 mg/day), losartan (100 mg/day), or quinapril plus losartan (20 mg/day+100 mg/day). LV systolic and diastolic function was assessed using radionuclide ventriculography (RNV) at baseline and after 12 months of treatment.

RESULTS

In all three treatment groups, abnormal CRT values were improved. In the quinapril group, the first third filling fraction (1/3FF, 48.9+/-17.8% vs. 39.2+/-12.9% at baseline, P=.005) was increased and the atrial contribution to ventricular filling (25.1+/-6.3 vs. 30.1+/-7.8, P=.027) was reduced in the losartan group; the peak filling rate (PFR) was improved (3.41+/-.62 vs. 3.11+/-.44 volumes/s, P=.05), and in the combination group, the 1/3FF (39.4+/-11.8% vs. 29.6+/-11.9%, P=.018) was markedly increased, while the time to peak filling (TPF; 147+/-42 vs. 184+/-33 ms, P=.02) and the TPF/filling time (TPF/FT; 32.5+/-6.2% vs. 38.2+/-5.7%, P=.016) were reduced.

CONCLUSIONS

Early ACE-I or ARB improve both DAN and LVDD in asymptomatic patients with Type 1 or 2 DM, after 1 year of treatment. Their combination may be slightly better than monotherapies on DAN and LVDD. The clinical importance of these effects should be validated by larger studies.

Impaired bradykinin response to ischaemia and exercise in patients with mild congestive heart failure during angiotensin-converting enzyme treatment. Relationships with endothelial function, coagulation and inflammation

Inflammation and endothelial dysfunction play important roles in the pathophysiology of congestive heart failure (CHF), and the peptide bradykinin, generated during inflammation, may act as a defence mechanism by inducing vasodilation. Plasma bradykinin levels are increased in experimental heart failure but low in patients with advanced chronic CHF despite treatment with angiotensin-converting enzyme (ACE) inhibitors. It is not currently known how bradykinin behaves in less severe phases of CHF controlled by long-term ACE inhibitor treatment. We studied 10 male patients with clinically stable chronic CHF [New York Heart Association (NYHA) class II] on long-term ACE inhibitor treatment and 10 normal sex- and age-matched control subjects. High performance liquid chromatography/radioimmunoassay methods were used to evaluate plasma levels of bradykinin in relation to an array of parameters of endothelial function, coagulation and inflammation before and after stimuli of forearm arterial occlusion and physical exercise. CHF patients had higher levels of bradykinin (P = 0.008), activated factor XII (P = 0.049), interleukin-6 (P = 0.050) and tumour necrosis factor receptor II (sTNFRII) (P = 0.026) than controls. Arterial occlusion and exercise significantly increased bradykinin and von Willebrand factor levels in controls but not in CHF patients. The increase in brachial artery diameter after arterial occlusion was less in CHF patients (P = 0.036) and inversely related to baseline plasma levels of bradykinin (r = -0.855, P = 0.002) and sTNFRII (r = -0.780, P = 0.008). NYHA class II CHF patients during long-term treatment with ACE inhibitors have increased bradykinin levels and signs of inflammation. They are unable to respond adequately to stimuli of ischaemia and physical exercise which both require vasodilation.

Contribution of vascular NAD(P)H oxidase to endothelial dysfunction in heart failure and the therapeutic effects of HMG-CoA reductase inhibitor

BACKGROUND

The vascular NAD(P)H oxidase-derived superoxide anion (O(2)-) plays a crucial role in the pathological progression of hypertension and atherosclerosis, and HMG-CoA reductase inhibitors (statins) have vascular antioxidant effects. However, it is unclear whether the vascular NAD(P)H oxidase is involved in the endothelial dysfunction of congestive heart failure (CHF) and whether HMG-CoA reductase inhibitors (statins) exert their vasoprotective effects in CHF. The present study examined both the involvement of vascular NAD(P)H oxidase in endothelial dysfunction in dogs with tachycardia-induced CHF and the therapeutic effect of a statin (pitavastatin).

METHODS AND RESULTS

Femoral blood flow (FBF) responses to acetylcholine was significantly impaired in the CHF group, but were improved by pitavastatin. Vascular O(2)- production, NAD(P)H oxidase activity and Nox4 and p47phox expression were significantly elevated in CHF compared with the normal group. The elevated O(2)-production in the CHF group was suppressed by the NAD(P)H oxidase inhibitor, apocynin, to the normal level. In contrast, neither the gene expression nor the activity of endothelial nitric oxide synthase (eNOS) differed significantly between the normal and CHF groups. However, pitavastatin significantly suppressed O(2)- production, NAD(P)H oxidase activity and Nox4 and p47phox expression and increased eNOS expression and activity compared with the CHF group.

CONCLUSIONS

The activated vascular NAD(P)H oxidase contributes to endothelial dysfunction in CHF, which was partly improved by pitavastatin via its inhibition of NAD(P)H oxidase.

Combined angiotensin receptor blocker and ACE inhibitor on myocardial fibrosis and left ventricular stiffness in dogs with heart failure

Angiotensin receptor blocker (ARB) and angiotensin-converting enzyme (ACE) inhibitor (ACEI) each act in a different manner to prevent myocardial fibrosis and left ventricular (LV) stiffness in animals with pathways in the heart for generating ANG II as well as ACE. A model of pacing-induced congestive heart failure (CHF) was used to test the central hypothesis that ARB + ACEI prevents myocardial fibrosis and decreases LV stiffness to a greater extent than ARB or ACEI alone. Thirty-five dogs were assigned to the following treatment protocols on the 8th day of a 4-wk pacing schedule: 1) rapid ventricular pacing, 2) ARB (candesartan cilexetil, 1.5 mg.kg(-1).day(-1)) with pacing, 3) ACEI (enalapril, 1.9 mg.kg(-1).day(-1)) with pacing, 4) ARB (candesartan cilexetil, 0.75 mg.kg(-1).day(-1)) + ACEI (enalapril, 0.95 mg.kg(-1).day(-1)) with pacing, and 5) sham operation. The LV stiffness coefficient was significantly increased after rapid pacing but was significantly lower with ARB + ACEI than with ARB or ACEI alone. The collagen volume fraction and mRNA levels of collagen I and III, which were increased by rapid pacing, were significantly lower with ARB + ACEI than with ARB or ACEI alone. Thus ARB + ACEI prevents myocardial fibrosis and decreases LV stiffness during the progression of CHF compared with ARB or ACEI alone.

Imidapril treatment improves the attenuated inotropic and intracellular calcium responses to ATP in heart failure due to myocardial infarction

1. Adenosine 5'-triphosphate (ATP) is known to augment cardiac contractile activity and cause an increase in intracellular Ca(2+) concentration ([Ca(2+)](i)) in isolated cardiomyocytes. However, no information regarding the ATP-mediated signal transduction in the myocardium in congestive heart failure (CHF) is available. 2. CHF due to myocardial infarction (MI) in rats was induced by the occlusion of the left coronary artery for 8 weeks. The positive inotropy due to ATP was depressed in failing hearts. Treatment of 3 weeks infarcted animals with imidapril (1 mg kg(-1) day(-1)) for a period of 5 weeks improved the left ventricle function and decreased the attenuation of inotropic response to ATP. 3. ATP-induced increase in [Ca(2+)](i) was significantly depressed in cardiomyocytes isolated from the failing heart and this change was partially attenuated by imidapril treatment. However, the binding characteristics of (35)S-labeled adenosine 5'-(gamma-thio) triphosphate in sarcolemma isolated from the failing heart remained unaltered. 4. ATP-induced increase in [Ca(2+)](i) was depressed by verapamil and cibacron blue in both control and failing heart cardiomyocytes; however, the ATP response in the failing hearts, unlike the control preparations, was not decreased by ryanodine. This insensitivity to ryanodine was attenuated by imidapril treatment. 5. Treatment of infarcted rats with enalapril and losartan produced effects similar to imidapril. 6. These findings indicate that the positive inotropic response to ATP and ATP-induced increase in [Ca(2+)](i) in cardiomyocytes are impaired in heart failure. Furthermore, blockade of renin angiotensin system prevented the impairment of the ATP-mediated inotropic and [Ca(2+)](i) responses in the failing heart.

Improvement of defective sarcoplasmic reticulum Ca2+transport in diabetic heart of transgenic rats expressing the human kallikrein‐1 gene

The bradykinin-forming enzyme kallikrein-1 is expressed in the heart. To examine whether contractile performance and sarcoplasmic reticulum Ca2+ transport of the diabetic heart can be rescued by targeting the kallikrein-kinin system, we studied left ventricular function and sarcoplasmic reticular Ca2+ uptake after induction of streptozotocin-induced diabetes mellitus in transgenic rats expressing the human tissue kallikrein-1 gene. Six weeks after a single injection of either streptozotocin (70 mg/kg ip) or vehicle, left ventricular performance was determined using a Millar-Tip catheter system. The Ca2+-transporting activity of reticulum-derived membrane vesicles was determined in left ventricular homogenates as oxalate-supported 45Ca2+ uptake. Western blot analysis was used to quantify the reticular Ca2+-ATPase SERCA2a, phospholamban, and the phosphorylation status of the latter. Contractile performance and Ca2+ uptake activity were similar in nondiabetic wild-type and transgenic rats. Severely diabetic wild-type animals exhibited impaired left ventricular performance and decreased reticular Ca2+ uptake (-39% vs. wild-type rats, P<0.05, respectively). These changes were attenuated in diabetic transgenic rats that, in addition, exhibited a markedly increased phospholamban phosphorylation at the Ca2+/calmodulin kinase-specific site threonine17 (2.2-fold vs. diabetic wild-type rats, P<0.05). These transgene-related effects were abolished after treatment with the bradykinin B2 receptor antagonist icatibant (Hoe 140). The SERCA2-to-phospholamban ratio, phosphoserine16-phospholamban levels, and the apparent affinity for Ca2+ of the uptake reaction did not differ between the groups. Increasing the activity of the kallikrein-kinin system by expressing a human kallikrein-1 transgene protects rat heart against diabetes-induced contractile and reticular Ca2+ transport dysfunctions. An increased phosphorylation of the SERCA2 regulatory protein phospholamban at threonine17 via a B2 receptor-mediated mechanism is thereby involved.

Candesartan Prevents Myocardial Fibrosis during Progression of Congestive Heart Failure

BACKGROUND

The goal of this study was to determine whether an Angiotensin II receptor antagonist, candesartan, prevents myocardial fibrosis more effectively than enalapril in animals with a non-ACE pathway during the progression of congestive heart failure (CHF).

METHODS AND RESULTS

Dogs were randomly assigned to one of four groups: (1) rapid ventricular pacing (240 bpm); (2) concomitant candesartan cilexetil (1.5 mg/kg/d) and rapid pacing; (3) concomitant enalapril (1.9 mg/kg/d) and rapid pacing; (4) sham-operated control. The expression of collagen type I & III mRNA and the collagen volume fraction, which were significantly increased in the pacing-only group, were suppressed by both treatments; it was lower in the candesartan than the enalapril group. Although there were no differences in the LV stiffness coefficient (beta) among all pacing groups, the absolute changes in beta from the control values were smaller in the candesartan group, but not the enalapril group, compared with the rapid-pacing-only group.

CONCLUSIONS

The present study demonstrates that in animals with a non-ACE pathway, candesartan suppressed myocardial fibrosis during the progression of CHF in comparison with enalapril. Furthermore, candesartan prevented an increase in LV stiffness. These findings imply potential clinical applications for candesartan in the management of CHF to prevent myocardial fibrosis. Further prospective evaluation and clinical study will be necessary before deciding on the net benefits of candesartan in comparison to enalapril.

Aldosterone antagonist facilitates the cardioprotective effects of angiotensin receptor blockers in hypertensive rats

BACKGROUND

There is increasing evidence to support the importance of blocking aldosterone to prevent target-organ damage in hypertension. We recently demonstrated an aldosterone breakthrough phenomenon during administration of an angiotensin type 1 receptor blocker (ARB).

OBJECTIVE

To elucidate the pathophysiological significance of residual aldosterone by investigating the influence of the aldosterone antagonist on the cardioprotective effects of the ARB in hypertensive rats.

METHODS

Injection vehicle alone, ARB (1.0 mg/kg per day candesartan by mouth), aldosterone antagonist (10 mg/kg per day spironolactone, subcutaneously), or combined treatment were administered to male stroke-prone spontaneously hypertensive rats for 24 weeks from the age of 4 weeks. Blood pressure, plasma angiotensin II and aldosterone concentrations, left ventricular weight, expression of type I and type III collagen mRNA, and histological findings were determined.

RESULTS

In the ARB-treated group, aldosterone concentrations remained unchanged (1.10 +/- 0.20 nmol/l, compared with 1.17 +/- 0.46 nmol/l in the control group), whereas systolic blood pressure (178 +/- 9 mmHg), left ventricular weight (0.372 +/- 0.035 g/100 g body weight), expression of collagen mRNA, and cardiac interstitial and perivascular fibrosis all decreased significantly compared with the control group (systolic blood pressure: 222 +/- 10 mmHg, P < 0.05; left ventricular weight: 0.483 +/- 0.021 g/100 g body weight, P < 0.05). Although blood pressure (217 +/- 9 mmHg) and left ventricular weight (0.467 +/- 0.027 g/100 g body weight) remained unchanged in the group receiving spironolactone, the expression of both types of collagen mRNA and cardiac interstitial and perivascular fibrosis showed a significant decrease compared with the vehicle-treated group. In the rats receiving combined treatment with the ARB and spironolactone, left ventricular weight (0.352 +/- 0.005 g/100 g body weight, P < 0.05), expression of collagen mRNA, and cardiac interstitial and perivascular fibrosis all showed a further improvement compared with both the ARB and spironolactone groups.

CONCLUSIONS

These results demonstrate that residual aldosterone has a significant impact on target-organ damage in hypertension, even during chronic administration of an ARB. The addition of an aldosterone antagonist has an advantage in facilitating the cardioprotective effects of ARBs.

Effects of losartan and captopril on left ventricular systolic and diastolic function after acute myocardial infarction: results of the Optimal Trial in Myocardial Infarction with Angiotensin II Antagonist Losartan (OPTIMAAL) echocardiographic substudy

BACKGROUND

Angiotensin-converting enzyme inhibitors have been shown to attenuate adverse remodeling after acute myocardial infarction (AMI), and the same has been suggested for angiotensin II type 1 receptor antagonists in animal models. Therefore the aim of the study was to compare the effects of losartan and captopril on regional systolic, diastolic, and overall left ventricular (LV) function after AMI.

METHODS

Two hundred twenty-five patients aged > or =50 years with documented AMI and heart failure and/or LV dysfunction were randomly assigned treatment with either losartan (50 mg/d) or captopril (50 mg 3 times/d). Echocardiography was performed at randomization and after 3 months; echocardiograms were analyzed blinded at the core laboratory. Main outcome measures were changes in wall motion score index (WMSI), E-wave deceleration time (E-DT), and Tei index of overall LV function.

RESULTS

WMSI decreased in both groups (losartan 1.58 +/- 0.23 to 1.52 +/- 0.26, P =.009, captopril 1.60 +/- 0.24 to 1.48 +/- 0.22, P <.001), although the decrease was greater in patients allocated to captopril (captopril -0.12 +/- 0.17 vs losartan -0.05 +/- 0.19, P =.007). In both groups E-DT increased, although the increase was significant only in patients treated with captoril (193 +/- 61 ms to 208 +/- 70 ms, P =.05). The change in E-DT was not different between treatment groups (captopril 14 +/- 74 ms vs losartan 7 +/- 80 ms, P =.52). Tei index decreased in both groups (losartan 0.59 +/- 0.13 to 0.55 +/- 0.15, P =.04, captopril 0.62 +/- 0.15 to 0.55 +/- 0.13, P <.001). However, the reduction was significantly greater in patients treated with captopril (captopril -0.08 +/- 0.14 vs losartan -0.03 +/- 0.14, P =.01).

CONCLUSION

Losartan and captopril improve systolic and overall LV function after AMI, but the benefit is greater for patients treated with captopril.

Chronic infusion of bradykinin delays the progression of heart failure and preserves vascular endothelium-mediated vasodilation in conscious dogs

BACKGROUND

This study examined the effects of chronic bradykinin infusion on hemodynamics and myocardial and endothelial functions during the development of heart failure.

METHODS AND RESULTS

Sixteen instrumented dogs were randomized to receive through the left atria either vehicle or bradykinin (1 microg/min) during ventricular pacing (250 bpm, 5 weeks). Hemodynamic and left ventricular (LV) parameters and the vasodilator responses to intravenous acetylcholine (0.3 to 3 microg/kg) and nitroglycerin (1 to 10 microg/kg) were examined in the control and after 3 and 5 weeks of pacing. The expression of endothelial NOS in femoral, carotid, and renal arteries was determined by Western blot analysis. After 3 weeks of pacing, changes in LV diastolic and systolic parameters were significantly lower in bradykinin-treated than vehicle-treated dogs (LV end-diastolic pressure, +10+/-3 versus +19+/-2 mm Hg; time constant of LV isovolumic relaxation, +11+/-2 versus +17+/-1 ms; LV wall thickening, -33+/-18% versus -75+/-9%; and cardiac output, -16+/-6% versus -32+/-6%; all P<0.05). Compared with vehicle-treated dogs, bradykinin-treated dogs had a reduced rightward shift of the diastolic LV pressure-diameter relation and a reduced diastolic LV wall stress. Similar trends were observed after 5 weeks. The vasodilator response to nitroglycerin was preserved in both groups. The response to acetylcholine was blunted in vehicle-treated but preserved in bradykinin-treated dogs. Vascular endothelial NOS expression decreased in vehicle-treated but was preserved in bradykinin-treated dogs.

CONCLUSIONS

In conscious dogs, chronic bradykinin infusion delays the heart failure progression by preserving LV diastolic and systolic functions and by preserving vascular endothelial function.

The kallikrein-kinin and the renin-angiotensin systems have a multilayered interaction

Understanding the physiological role of the plasma kallikrein-kinin system (KKS) has been hampered by not knowing how the proteins of this proteolytic system, when assembled in the intravascular compartment, become activated under physiological conditions. Recent studies indicate that the enzyme prolylcarboxypeptidase, an ANG II inactivating enzyme, is a prekallikrein activator. The ability of prolylcarboxypeptidase to act in the KKS and the renin-angiotensin system (RAS) indicates a novel interaction between these two systems. This interaction, along with the roles of angiotensin converting enzyme, cross talk between bradykinin and angiotensin-(1-7) action, and the opposite effects of activation of the ANG II receptors 1 and 2 support a hypothesis that the plasma KKS counterbalances the RAS. This review examines the interaction and cross talk between these two protein systems. This analysis suggests that there is a multilayered interaction between these two systems that are important for a wide array of physiological functions.

Chymase inhibition prevents cardiac fibrosis and improves diastolic dysfunction in the progression of heart failure

BACKGROUND

Angiotensin (Ang) II, which plays a crucial role in the cardiac remodeling process, is generated via angiotensin-converting enzyme (ACE); however, an alternative generation pathway, chymase, which is stored in the mast cells, also exists in the heart. Cardiac chymase is insensitive to ACE inhibitors (ACEIs), and heart chymase promotes interstitial fibrosis by affecting collagen metabolism via transforming growth factor-beta in vitro. Therefore, selective chymase blockade seems to be an important strategy in the prevention of cardiac remodeling

METHODS AND RESULTS

We evaluated the effects of a specific chymase inhibitor, SUNC8257 (Chy I; 10 mg/kg twice a day; n=7), on changes in cardiac structures, Ang II levels, and gene expressions, which are characterized as molecular markers for fibrosis, in dogs with tachycardia induced heart failure (HF). In HF, the number of chymase enzyme-positive mast cells increased in the left ventricle (LV) compared with the normal group; however, Chy I significantly decreased the mast cell density and cardiac Ang II levels. Despite no significant differences in LV systolic function compared with the vehicle group, Chy I decreased LV end-diastolic pressure and shortened the prolongation of tau. Chy I suppressed collagen-type I and III and transforming growth factor-beta mRNA levels and decreased fibrosis in the LV compared with the vehicle.

CONCLUSIONS

The chymase pathway may be critical for cardiac diastolic dysfunction accompanied with fibrosis. Chronic chymase inhibition may therefore become an important strategy in the prevention of cardiac remodeling in HF.

The therapeutic potential of bradykinin B2 receptor agonists in the treatment of cardiovascular disease

The nonapeptide bradykinin (BK) is a Janus-faced hormone, which exerts pathophysiological as well as pronounced beneficial physiological effects, mainly by stimulation of BK B(2) receptors. In various animal models and in humans it has been shown that the stimulation of BK B(2) receptors is not only implicated in the pathogenesis of inflammation, pain and tissue injury but also in powerful cardioprotective mechanisms. Either exogenous administration of BK or locally increased BK concentrations as a consequence of the inhibition of its metabolic breakdown by angiotensin-converting enzyme inhibitors, reveal the significant contribution of BK in powerful cardioprotective mechanisms. These are mainly triggered by the synthesis and release of the vasorelaxant, anti-hypertrophic and anti-atherosclerotic endothelial mediators nitric oxide, prostaglandins and tissue-type plasminogen activator, by ischaemic preconditioning and by an increase in insulin sensitivity. Consequently, BK B(2) receptor agonists may have important clinical value in the treatment and prevention of various cardiovascular disorders such as hypertension, ischaemic heart disease, left ventricular hypertrophy, ventricular remodelling and congestive heart failure as well as diabetic disorders by mimicking the reported beneficial effects of BK. However, none of the currently known potent and selective peptide and non-peptide agonists of BK B(2) receptors--RMP-7 (lobradamil, Cereport; Alkermes), JMV-1116 (Fournier), FR-190997 (Fujisawa) and FR-191413 (Fujisawa)--have been selected for a clinical assessment in cardiovascular indications. One major challenge of this approach is the still unanswered question of whether there is a sufficient safe therapeutic window between potential cardioprotective and pro-inflammatory effects following BK B(2) receptor agonism.