Effect of carvedilol in comparison with metoprolol on myocardial collagen postinfarction

Baoyuan decoction (BYD) attenuates cardiac hypertrophy through ANKRD1-ERK/GATA4 pathway in heart failure after acute myocardial infarction

BACKGROUND

The pathological cardiac functions of ankyrin repeat domain 1 (ANKRD1) in left ventricle can directly aggravate cardiac hypertrophy (CH) and fibrosis through the activation of extracellular signal-regulated kinase (ERK)/ transcription factor GATA binding protein 4 (GATA4) pathway, and subsequently contribute to heart failure (HF). Baoyuan Decoction (BYD), which is a famous classic Chinese medicinal formulation, has shown impressive cardioprotective effects clinically and experimentally. However, the knowledge is still limited in its underlying mechanisms against HF.

PURPOSE

To explore whether BYD plays a protective role against HF by attenuating CH via the ANKRD1-ERK/GATA4 pathway.

METHODS

In vivo, HF rat models were prepared using left anterior descending coronary artery (LADCA) ligation. Rats in the BYD group were administered a dosage of 2.57 g/kg of BYD for 28 days, while in the positive control group rats were given 4.67 mg/kg of Fosinopril. In vitro, a hypertrophic model was constructed by stimulating H9C2 cells with 1 uM Ang II. An ANKRD1-overexpressing cell model was established through transient transfection of ANKRD1 plasmid into H9C2 cells. Subsequently, BYD intervention was performed on the cell models to further elucidate its effects and underlying mechanism.

RESULTS

In vivo results showed that BYD significantly improved cardiac function and inhibited pathological hypertrophy and fibrosis in a rat model of HF post-acute myocardial infarction (AMI). Noticeably, label-free proteomic analysis demonstrated that BYD could reverse the CH-related biological turbulences, mainly through ANKRD1-ERK/GATA4 pathway. Further in vitro results validated that the hypertrophy was attenuated by BYD through suppression of AT1R, ANKRD1, Calpain1, p-ERK1/2 and p-GATA4. The results of in vitro model indicated that BYD could reverse the outcome of transfected over-expression of ANKRD1, including down-regulated expressions of ANKRD1, p-ERK1/2 and p-GATA4.

CONCLUSION

BYD ameliorates CH and improves HF through the ANKRD1-ERK/GATA4 pathway, providing a novel therapeutic option for the treatment of HF.

Preclinical rodent models of cardiac fibrosis

Cardiac fibrosis (scarring), characterised by an increased deposition of extracellular matrix (ECM) proteins, is a hallmark of most types of cardiovascular disease and plays an essential role in heart failure progression. Inhibition of cardiac fibrosis could improve outcomes in patients with cardiovascular diseases and particularly heart failure. However, pharmacological treatment of the ECM build-up is still lacking. In this context, preclinical models of heart disease are important tools for understanding the complex pathogenesis involved in the development of cardiac fibrosis which in turn could identify new therapeutic targets and the facilitation of antifibrotic drug discovery. Many preclinical models have been used to study cardiac fibrosis and each model provides mechanistic insights into the many factors that contribute to cardiac fibrosis. This review discusses the most frequently used rodent models of cardiac fibrosis and also provides context for the use of particular models of heart failure.

Photobiomodulation therapy combined with carvedilol attenuates post-infarction heart failure by suppressing excessive inflammation and oxidative stress in rats

The post-myocardial infarction heart failure (HF) still carries a huge burden since current therapy is unsuccessful to abrogate poor prognosis. Thus, new approaches are needed, and photobiomodulation therapy (PBMt) may be a way. However, it is not known whether PBMt added to a standard HF therapy provides additional improvement in cardiac remodeling in infarcted rats. This study sought to determine the combined carvedilol-drug and PBMt with low-level laser therapy value in HF. Rats with large infarcts were treated for 30 days. The functional fitness was evaluated using a motorized treadmill. Echocardiography and hemodynamic measurements were used for functional evaluations of left ventricular (LV). ELISA, Western blot and biochemical assays were used to evaluate inflammation and oxidative stress in the myocardium. Carvedilol and PBMt had a similar action in normalizing pulmonary congestion and LV end-diastolic pressure, attenuating LV dilation, and improving LV systolic function. Moreover, the application of PBMt to carvedilol-treated rats inhibited myocardial hypertrophy and improved +dP/dt of LV. PBMt alone prevented inflammation with a superior effect than carvedilol. Carvedilol and PBMt normalized 4-hydroxynonenal (a lipoperoxidation marker) levels in the myocardium. However, importantly, the addition of PBMt to carvedilol attenuated oxidized protein content and triggered a high activity of the anti-oxidant catalase enzyme. In conclusion, these data show that the use of PBMt plus carvedilol therapy results in a significant additional improvement in HF in a rat model of myocardial infarction. These beneficial effects were observed to be due, at least in part, to decreased myocardial inflammation and oxidative stress.

Biomaterials and heart recovery: cardiac repair, regeneration and healing in the MCS era: a state of the "heart"

Regenerative medicine is an emerging interdisciplinary field of scientific research that, supported by tissue engineering is, nowadays, a valuable and reliable solution dealing with the actual organs shortage and the unresolved limits of biological or prosthetic materials used in repair and replacement of diseased or damaged human tissues and organs. Due to the improvements in design and materials, and to the changing of clinical features of patients treated for valvular heart disease the distance between the ideal valve and the available prostheses has been shortened. We will then deal with the developing of new tools aiming at replacing or repair cardiac tissues that still represent an unmet clinical need for the surgeons and indeed for their patients. In the effort of improving treatment for the cardiovascular disease (CVD), scientists struggle with the lack of self-regenerative capacities of finally differentiated cardiovascular tissues. In this context, using several converging technological approaches, regenerative medicine moves beyond traditional transplantation and replacement therapies and can restore tissue impaired function. It may also play an essential role in surgery daily routine, leading to produce devices such as injectable hydrogels, cardiac patches, bioresorbable stents and vascular grafts made by increasingly sophisticated biomaterial scaffolds; tailored devices promptly fabricated according to surgeon necessity and patient anatomy and pathology will hopefully represent a daily activity in the next future. The employment of these devices, still far from the in vitro reproduction of functional organs, has the main aim to achieve a self-renewal process in damaged tissues simulating endogenous resident cell populations. In this field, the collaboration and cooperation between cardiothoracic surgeons and bioengineers appear necessary to modify these innovative devices employed in preclinical studies according to the surgeon's needs.

Increased collagen within the transverse tubules in human heart failure

Aims

In heart failure transverse-tubule (t-tubule) remodelling disrupts calcium release, and contraction. T-tubules in human failing hearts exhibit increased labelling by wheat germ agglutinin (WGA), a lectin that binds to the dystrophin-associated glycoprotein complex. We hypothesized changes in this complex may explain the increased WGA labelling and contribute to t-tubule remodelling in the failing human heart. In this study we sought to identify the molecules responsible for this increased WGA labelling.

Methods and results

Confocal and super-resolution fluorescence microscopy and proteomic analyses were used to quantify left ventricle samples from healthy donors and patients with idiopathic dilated cardiomyopathy (IDCM). Confocal microscopy demonstrated both WGA and dystrophin were located at t-tubules. Super-resolution microscopy revealed that WGA labelling of t-tubules is largely located within the lumen while dystrophin was restricted to near the sarcolemma. Western blots probed with WGA reveal a 5.7-fold increase in a 140 kDa band in IDCM. Mass spectrometry identified this band as type VI collagen (Col-VI) comprised of α1(VI), α2(VI), and α3(VI) chains. Pertinently, mutations in Col-VI cause muscular dystrophy. Western blotting identified a 2.4-fold increased expression and 3.2-fold increased WGA binding of Col-VI in IDCM. Confocal images showed that Col-VI is located in the t-tubules and that their diameter increased in the IDCM samples. Super-resolution imaging revealed Col-VI was restricted to the t-tubule lumen where increases were associated with displacement in the sarcolemma as identified from dystrophin labelling. Samples were also labelled for type I, III, and IV collagen. Both confocal and super-resolution imaging identified that these collagens were also present within t-tubule lumen.

Conclusion

Increased expression and labelling of collagen in IDCM samples indicates fibrosis may contribute to t-tubule remodelling in human heart failure.

Transverse tubule remodelling: a cellular pathology driven by both sides of the plasmalemma?

Transverse (t)-tubules are invaginations of the plasma membrane that form a complex network of ducts, 200-400 nm in diameter depending on the animal species, that penetrates deep within the cardiac myocyte, where they facilitate a fast and synchronous contraction across the entire cell volume. There is now a large body of evidence in animal models and humans demonstrating that pathological distortion of the t-tubule structure has a causative role in the loss of myocyte contractility that underpins many forms of heart failure. Investigations into the molecular mechanisms of pathological t-tubule remodelling to date have focused on proteins residing in the intracellular aspect of t-tubule membrane that form linkages between the membrane and myocyte cytoskeleton. In this review, we shed light on the mechanisms of t-tubule remodelling which are not limited to the intracellular side. Our recent data have demonstrated that collagen is an integral part of the t-tubule network and that it increases within the tubules in heart failure, suggesting that a fibrotic mechanism could drive cardiac junctional remodelling. We examine the evidence that the linkages between the extracellular matrix, t-tubule membrane and cellular cytoskeleton should be considered as a whole when investigating the mechanisms of t-tubule pathology in the failing heart.

Carvedilol attenuates paraquat-induced lung injury by inhibition of proinflammatory cytokines, chemokine MCP-1, NF-κB activation and oxidative stress mediators

Paraquat is a highly toxic herbicide that selectively accumulates in the lungs and causes pulmonary damage through the oxidative and inflammatory processes. Carvedilol is a nonselective beta and alpha-adrenergic blocking agent that has been shown to possess powerful antioxidant and anti-inflammatory properties. In the present study, we evaluated the protective effects and the underlying mechanisms of carvedilol on paraquat-induced lung injury in a mouse model. Mice were injected with a single dose of paraquat (20mg/kg, ip), and treated with carvedilol (10 and 20mg/kg/day, orally) for eight days. At the end of the experiment, lung tissue and blood samples were collected for histological and biochemical analysis. The results showed that carvedilol treatment improved the histopathological changes in the lung tissue of mice exposed to paraquat. Carvedilol significantly decreased the levels of malondialdehyde (MDA), carbonyl protein, myeloperoxidase (MPO), and nitric oxide (NO), while increased the levels of glutathione (GSH), superoxide dismutase (SOD), catalase and glutathione reductase compared with paraquat group. Carvedilol treatment also significantly reduced the levels of proinflammatory cytokines tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, transforming growth factor (TGF)-β1 and monocyte chemoattractant protein (MCP)-1 in the lung tissue. Treatment of mice with carvedilol decreased paraquat-induced expression of nuclear factor kappa B (NF-κB). In addition the plasma levels of matrix metalloproteinase (MMP)-9 and the lung hydroxyproline content significantly reduced by carvedilol treatment. Taken together, these results indicate that carvedilol is able to decrease the severity of paraquat-induced lung injury through inhibition of inflammation and oxidative stress.

Effects of carvedilol on ventricular remodeling and the expression of β3-adrenergic receptor in a diabetic rat model subjected myocardial infarction

BACKGROUND

This study was to assess effects of carvedilol on ventricular remodeling and expression of β3-adrenergic receptor (β3-AR) and Gi protein in a rat model of diabetes subjected to myocardial infarction (MI).

METHODS

Rat model of type II diabetes was established by injection of streptozotion. MI was then induced by ligating the left anterior descending coronary artery. Rats were then randomly divided into two groups treated with either placebo (PL) or carvedilol (CA - 10mg·kg(-1)·d(-)(1)). Additional controls consisted of sham-operated rats with diabetes (DS) and rats fed a normal diet subjected to myocardial infarction (NM). Echocardiographic and hemodynamic studies were performed to assess the structural and functional changes. β3-AR and Gi mRNA in the myocardium distal from the infarction region were measured, and β3-AR and Gi protein were measured with western blot.

RESULTS

There were no significant differences in MI size among the three MI groups. In the PL group, LVEDd, LVWI, E/A and CVF were significantly increased, while LVEF and PW% significantly decreased as compared with the DS and NM groups. Compared with the DS group, the expression of β3-AR and Gi mRNA and protein in the PL group was significantly increased, however, in the CA group, β3-AR and Gi mRNA and protein were decreased.

CONCLUSIONS

The expression of β3-AR and Gi mRNA and protein was increased in diabetic rats subjected to MI as compared with rats subject to either condition alone. Carvedilol treatment prevented many of these deleterious effects.

Nebivolol versus Carvedilol or Metoprolol in Patients Presenting with Acute Myocardial Infarction Complicated by Left Ventricular Dysfunction

OBJECTIVE

The aim of this study was to evaluate the efficacy of nebivolol, carvedilol or metoprolol succinate on the outcome of patients presenting with acute myocardial infarction (AMI) complicated by left ventricular dysfunction.

SUBJECTS AND METHODS

Patients (n = 172, aged 28-87 years) with AMI and left ventricular ejection fraction ≤0.45 were randomized to the nebivolol (n = 55), carvedilol (n = 60) and metoprolol succinate (n = 57) groups. Baseline demographic and clinical characteristics and composite event rates of nonfatal MI, cardiovascular mortality, hospitalization due to unstable angina pectoris or heart failure, stroke or revascularization during the 12-month follow-up were compared among the groups using the x03C7;2 test, t test or log-rank test as appropriate.

RESULTS

Baseline demographic and clinical characteristics were similar in the three groups. The composite end point during follow-up was lower in the patients treated with nebivolol than those treated with metoprolol (14.5 vs. 31.5%; p = 0.03). However, event rates were similar between the patients treated with carvedilol and those treated with the metoprolol (20.3 vs. 31.5%, p > 0.05) and between the patients treated with nebivolol and carvedilol (14.5 vs. 20.3%, p > 0.05).

CONCLUSION

The patients treated with nebivolol experienced 12-month cardiovascular events at a lower rate than those treated with metoprolol succinate. However, event rates were similar between the carvedilol and the metoprolol succinate groups and between the nebivolol and the carvedilol groups.

Physiological Implications of Myocardial Scar Structure

Once myocardium dies during a heart attack, it is replaced by scar tissue over the course of several weeks. The size, location, composition, structure, and mechanical properties of the healing scar are all critical determinants of the fate of patients who survive the initial infarction. While the central importance of scar structure in determining pump function and remodeling has long been recognized, it has proven remarkably difficult to design therapies that improve heart function or limit remodeling by modifying scar structure. Many exciting new therapies are under development, but predicting their long-term effects requires a detailed understanding of how infarct scar forms, how its properties impact left ventricular function and remodeling, and how changes in scar structure and properties feed back to affect not only heart mechanics but also electrical conduction, reflex hemodynamic compensations, and the ongoing process of scar formation itself. In this article, we outline the scar formation process following a myocardial infarction, discuss interpretation of standard measures of heart function in the setting of a healing infarct, then present implications of infarct scar geometry and structure for both mechanical and electrical function of the heart and summarize experiences to date with therapeutic interventions that aim to modify scar geometry and structure. One important conclusion that emerges from the studies reviewed here is that computational modeling is an essential tool for integrating the wealth of information required to understand this complex system and predict the impact of novel therapies on scar healing, heart function, and remodeling following myocardial infarction.

Impact of combined clenbuterol and metoprolol therapy on reverse remodelling during mechanical unloading

Background

Clenbuterol (Cl), a β₂ agonist, is associated with enhanced myocardial recovery during left ventricular assist device (LVAD) support, and exerts beneficial remodelling effects during mechanical unloading (MU) in rodent heart failure (HF). However, the specific effects of combined Cl+β₁ blockade during MU are unknown.

Methods and Results

We studied the chronic effects (4 weeks) of β₂-adrenoceptor (AR) stimulation via Cl (2 mg/kg/day) alone, and in combination with β₁-AR blockade using metoprolol ((Met), 250 mg/kg/day), on whole heart/cell structure, function and excitation-contraction (EC) coupling in failing (induced by left coronary artery (LCA) ligation), and unloaded (induced by heterotopic abdominal heart transplantation (HATx)) failing rat hearts. Combined Cl+Met therapy displayed favourable effects in HF: Met enhanced Cl's improvement in ejection fraction (EF) whilst preventing Cl-induced hypertrophy and tachycardia. During MU combined therapy was less beneficial than either mono-therapy. Met, not Cl, prevented MU-induced myocardial atrophy, with increased atrophy occurring during combined therapy. MU-induced recovery of Ca²⁺ transient amplitude, speed of Ca²⁺ release and sarcoplasmic reticulum Ca²⁺ content was enhanced equally by Cl or Met mono-therapy, but these benefits, together with Cl's enhancement of sarcomeric contraction speed, and MU-induced recovery of Ca²⁺ spark frequency, disappeared during combined therapy.

Conclusions

Combined Cl+Met therapy shows superior functional effects to mono-therapy in rodent HF, but appears inferior to either mono-therapy in enhancing MU-induced recovery of EC coupling. These results suggest that combined β₂-AR simulation +β₁-AR blockade therapy is likely to be a safe and beneficial therapeutic HF strategy, but is not as effective as mono-therapy in enhancing myocardial recovery during LVAD support.

Single intracoronary injection of encapsulated antagomir-92a promotes angiogenesis and prevents adverse infarct remodeling

Background

Small and large preclinical animal models have shown that antagomir‐92a‐based therapy reduces early postischemic loss of function, but its effect on postinfarction remodeling is not known. In addition, the reported remote miR‐92a inhibition in noncardiac organs prevents the translation of nonvectorized miR‐targeted therapy to the clinical setting. We investigated whether a single intracoronary administration of antagomir‐92a encapsulated in microspheres could prevent deleterious remodeling of myocardium 1 month after acute myocardial infarction AUTHOR: Should “acute” be added before “myocardial infarction” (since abbreviation is AMI)? Also check at first mention in main text (AMI) without adverse effects.

Methods and Results

In a percutaneous pig model of reperfused AMI, a single intracoronary administration of antagomir‐92a encapsulated in specific microspheres (9 μm poly‐d,‐lactide‐co‐glycolide [PLGA]) inhibited miR‐92a in a local, selective, and sustained manner (n=3 pigs euthanized 1, 3, and 10 days after treatment; 8×, 2×, and 5×‐fold inhibition at 1, 3, and 10 days). Downregulation of miR‐92a resulted in significant vessel growth (n=27 adult minipigs randomly allocated to blind receive encapsulated antagomir‐92a, encapsulated placebo, or saline [n=8, 9, 9]; P=0.001), reduced regional wall‐motion dysfunction (P=0.03), and prevented adverse remodeling in the infarct area 1 month after injury (P=0.03). Intracoronary injection of microspheres had no significant adverse effect in downstream myocardium in healthy pigs (n=2), and fluorescein isothiocyanate albumin‐PLGA microspheres were not found in myocardium outside the left anterior descending coronary artery territory (n=4) or in other organs (n=2).

Conclusions

Early single intracoronary administration of encapsulated antagomir‐92a in an adult pig model of reperfused AMI prevents left ventricular remodeling with no local or distant adverse effects, emerging as a promising therapeutic approach to translate to patients who suffer a large AMI.

Changes in cardiac aldosterone and its synthase in rats with chronic heart failure: an intervention study of long-term treatment with recombinant human brain natriuretic peptide

The physiological mechanisms involved in isoproterenol (ISO)-induced chronic heart failure (CHF) are not fully understood. In this study, we investigated local changes in cardiac aldosterone and its synthase in rats with ISO-induced CHF, and evaluated the effects of treatment with recombinant human brain natriuretic peptide (rhBNP). Sprague-Dawley rats were divided into 4 different groups. Fifty rats received subcutaneous ISO injections to induce CHF and the control group (n=10) received equal volumes of saline. After establishing the rat model, 9 CHF rats received no further treatment, rats in the low-dose group (n=8) received 22.5 μg/kg rhBNP and those in the high-dose group (n=8) received 45 μg/kg rhBNP daily for 1 month. Cardiac function was assessed by echocardiographic and hemodynamic analysis. Collagen volume fraction (CVF) was determined. Plasma and myocardial aldosterone concentrations were determined using radioimmunoassay. Myocardial aldosterone synthase (CYP11B2) was detected by quantitative real-time PCR. Cardiac function was significantly lower in the CHF group than in the control group (P<0.01), whereas CVF, plasma and myocardial aldosterone, and CYP11B2 transcription were significantly higher than in the control group (P<0.05). Low and high doses of rhBNP significantly improved hemodynamics (P<0.01) and cardiac function (P<0.05) and reduced CVF, plasma and myocardial aldosterone, and CYP11B2 transcription (P<0.05). There were no significant differences between the rhBNP dose groups (P>0.05). Elevated cardiac aldosterone and upregulation of aldosterone synthase expression were detected in rats with ISO-induced CHF. Administration of rhBNP improved hemodynamics and ventricular remodeling and reduced myocardial fibrosis, possibly by downregulating CYP11B2 transcription and reducing myocardial aldosterone synthesis.

Mineralocorticoid and AT1 receptors in the paraventricular nucleus contribute to sympathetic hyperactivity and cardiac dysfunction in rats post myocardial infarct

Intracerebroventricular infusion of a mineralocorticoid receptor (MR) or angiotensin II type 1 receptor (AT1R) blocker in rats attenuates sympathetic hyperactivity and progressive left ventricular (LV) dysfunction post myocardial infarction (MI). The present study examined whether knockdown of MRs or AT1Rs specifically in the paraventricular nucleus (PVN) contributes to these effects, and compared cardiac effects with those of systemic treatment with the β1-adrenergic receptor blocker metoprolol. The PVN of rats was infused with adeno-associated virus carrying small interfering RNA against either MR (AAV-MR-siRNA) or AT1R (AAV-AT1R-siRNA), or as control scrambled siRNA. At 4 weeks post MI, AT1R but not MR expression was increased in the PVN, excitatory renal sympathetic nerve activity and pressor responses to air stress were enhanced, and arterial baroreflex function was impaired; LV end-diastolic pressure (LVEDP) was increased and LV peak systolic pressure (LVPSP), ejection fraction (EF) and dP/dtmax decreased. AAV-MR-siRNA and AAV-AT1R-siRNA both normalized AT1R expression in the PVN, similarly ameliorated sympathetic and pressor responses to air stress, largely prevented baroreflex desensitization, and improved LVEDP, EF and dP/dtmax as well as cardiac interstitial (but not perivascular) fibrosis. In a second set of rats, metoprolol at 70 or 250 mg kg(-1) day(-1) in the drinking water for 4 weeks post MI did not improve LV function except for a decrease in LVEDP at the lower dose. These results suggest that in rats MR-dependent upregulation of AT1Rs in the PVN contributes to sympathetic hyperactivity, and LV dysfunction and remodelling post MI. In rats, normalizing MR-AT1R signalling in the PVN is a more effective strategy to improve LV dysfunction post MI than systemic β1 blockade.

Dynamic changes in myocardial matrix and relevance to disease: translational perspectives

The cardiac extracellular matrix (ECM) provides the architectural scaffold to support efficient contraction and relaxation of cardiomyocytes. The elegant design of the ECM facilitates optimal force transduction, electric transmission, intercellular communication, and metabolic exchange within the myocardial microenvironment. In the setting of increased wall stress, injury, or disease, the ECM can undergo a series of dynamic changes that lead to favorable chamber remodeling and functional adaptation. Over time, sustained matrix remodeling can impair diastolic and systolic function caused by excess deposition of interstitial fibrous tissue. These pathological alterations in ECM structure/function are considered central to the evolution of adverse cardiac remodeling and the development of heart failure. This review discusses the complex dynamics of the cardiac ECM in the setting of myocardial infarction, pressure overload, and volume overload. We also summarize the current status of ECM biomarkers that may have clinical value in prognosticating cardiac disease progression in patients. Finally, we discuss the most current status of drugs under evaluation for use in cardiac fibrosis.

Smad3 inactivation and MiR-29b upregulation mediate the effect of carvedilol on attenuating the acute myocardium infarction-induced myocardial fibrosis in rat

Carvedilol, a nonselective β-adrenoreceptor antagonist, protects against myocardial injury induced by acute myocardium infarction (AMI). The mechanisms underlying the anti-fibrotic effects of carvedilol are unknown. Recent studies have revealed the critical role of microRNAs (miRNAs) in a variety of cardiovascular diseases. This study investigated whether miR-29b is involved in the cardioprotective effect of carvedilol against AMI-induced myocardial fibrosis. Male SD rats were randomized into several groups: the sham surgery control, left anterior descending (LAD) surgery-AMI model, AMI plus low-dose carvedilol treatment (1 mg/kg per day, CAR-L), AMI plus medium-dose carvedilol treatment (5 mg/kg per day, CAR-M) and AMI plus high-dose carvedilol treatment (10 mg/kg per day, CAR-H). Cardiac remodeling and impaired heart function were observed 4 weeks after LAD surgery treatment; the observed cardiac remodeling, decreased ejection fraction, and fractional shortening were rescued in the CAR-M and CAR-H groups. The upregulated expression of Col1a1, Col3a1, and α-SMA mRNA was significantly reduced in the CAR-M and CAR-H groups. Moreover, the downregulated miR-29b was elevated in the CAR-M and CAR-H groups. The in vitro study showed that Col1a1, Col3a1, and α-SMA were downregulated and miR-29b was upregulated by carvedilol in a dose-dependent manner in rat cardiac fibroblasts. Inhibition of ROS-induced Smad3 activation by carvedilol resulted in downregulation of Col1a1, Col3a1, and α-SMA and upregulation of miR-29b derived from the miR-29b-2 precursor. Enforced expression of miR-29b significantly suppressed Col1a1, Col3a1, and α-SMA expression. Taken together, we found that smad3 inactivation and miR-29b upregulation contributed to the cardioprotective activity of carvedilol against AMI-induced myocardial fibrosis.

Carvedilol prevents ovariectomy-induced myocardial contractile dysfunction in female rat

Carvedilol has beneficial effects on cardiac function in patients with heart failure but its effect on ovariectomy-induced myocardial contractile dysfunction remains unclear. Estrogen deficiency induces myocardial contractile dysfunction and increases cardiovascular disease risk in postmenopausal women. Our aim was to investigate whether carvedilol, a beta receptor blocker, would prevent ovariectomy-induced myocardial contractile dysfunction. Female rats (8 weeks old) that underwent bilateral ovariectomy were randomly assigned to receive daily treatment with carvedilol (OVX+CAR, 20 mg/kg), placebo (OVX) and SHAM for 58 days. Left ventricle papillary muscle was mounted for isometric tension recordings. The inotropic response to Ca²⁺ (0.62 to 3.75 mM) and isoproterenol (Iso 10⁻⁸ to 10⁻² M) were assessed. Expression of calcium handling proteins was measured by western blot analysis. Carvedilol treatment in the OVX animals: prevented weight gain and slight hypertrophy, restored the reduced positive inotropic responses to Ca²⁺ and isoproterenol, prevented the reduction in SERCA2a expression, abolished the increase in superoxide anion production, normalized the increase in p22^phox expression, and decreased serum angiotensin converting enzyme (ACE) activity. This study demonstrated that myocardial contractile dysfunction and SERCA2a down regulation were prevented by carvedilol treatment. Superoxide anion production and NADPH oxidase seem to be involved in this response.

Functional evidence for an active role of B-type natriuretic peptide in cardiac remodelling and pro-arrhythmogenicity

AIMS

During heart failure (HF), the left ventricle (LV) releases B-type natriuretic peptide (BNP), possibly contributing to adverse cardiovascular events including ventricular arrhythmias (VAs) and LV remodelling. We investigated the cardiac effects of chronic BNP elevation in healthy mice and compared the results with a model of HF after myocardial infarction (PMI mice).

METHODS AND RESULTS

Healthy mice were exposed to circulating BNP levels (BNP-Sham) similar to those measured in PMI mice. Telemetric surface electrocardiograms showed that in contrast with fibrotic PMI mice, electrical conduction was not affected in BNP-Sham mice. VAs were observed in both BNP-Sham and PMI but not in Sham mice. Analysis of heart rate variability indicated that chronic BNP infusion increased cardiac sympathetic tone. At the cellular level, BNP reduced Ca(2+) transients and impaired Ca(2+) reuptake in the sarcoplasmic reticulum, in line with blunted SR Ca(2+) ATPase 2a and S100A1 expression. BNP increased Ca(2+) spark frequency, reflecting Ca(2+) leak through ryanodine receptors, elevated diastolic Ca(2+), and promoted spontaneous Ca(2+) waves. Similar effects were observed in PMI mice. Most of these effects were reduced in BNP-Sham and PMI mice by the selective β1-adrenergic blocker metoprolol.

CONCLUSION

Elevated BNP levels, by inducing sympathetic overdrive and altering Ca(2+) handling, promote adverse cardiac remodelling and VAs, which could account in part for the progression of HF after MI. The early use of β-blockers to prevent the deleterious effects of chronic BNP exposure may be beneficial in HF.

New therapeutic aspect for carvedilol: antifibrotic effects of carvedilol in chronic carbon tetrachloride-induced liver damage

Portal hypertension is a common complication of chronic liver diseases associated with liver fibrosis and cirrhosis. At present, beta-blockers such as carvedilol remain the medical treatment of choice for protection against variceal bleeding and other complications. Since carvedilol has powerful antioxidant properties we assessed the potential antifibrotic effects of carvedilol and the underlying mechanisms that may add further benefits for its clinical usefulness using a chronic model of carbon tetrachloride (CCl4)-induced hepatotoxicity. Two weeks after CCl4 induction of chronic hepatotoxicity, rats were co-treated with carvedilol (10mg/kg, orally) daily for 6weeks. It was found that treatment of animals with carvedilol significantly counteracted the changes in liver function and histopathological lesions induced by CCl4. Also, carvedilol significantly counteracted lipid peroxidation, GSH depletion, and reduction in antioxidant enzyme activities; glutathione-S-transferase and catalase that was induced by CCl4. In addition, carvedilol ameliorated the inflammation induced by CCl4 as indicated by reducing the serum level of acute phase protein marker; alpha-2-macroglobulin and the liver expression of nuclear factor-kappa B (NF-κB). Finally, carvedilol significantly reduced liver fibrosis markers including hydroxyproline, collagen accumulation, and the expression of the hepatic stellate cell (HSC) activation marker; alpha smooth muscle actin. In conclusion, the present study provides evidences for the promising antifibrotic effects of carvedilol that can be explained by amelioration of oxidative stress through mainly, replenishment of GSH, restoration of antioxidant enzyme activities and reduction of lipid peroxides as well as amelioration of inflammation and fibrosis by decreasing collagen accumulation, acute phase protein level, NF-κB expression and finally HSC activation.

β-Adrenergic receptor antagonists ameliorate myocyte T-tubule remodeling following myocardial infarction

β-Adrenergic receptor (AR) blockers provide substantial clinical benefits, including improving overall survival and left ventricular (LV) function following myocardial infarction (MI), though the mechanisms remain incompletely defined. The transverse-tubule (T-tubule) system of ventricular myocytes is an important determinant of cardiac excitation-contraction function. T-tubule remodeling occurs early during LV failure. We hypothesized that β-AR blockers prevent T-tubule remodeling and thereby provide therapeutic benefits. A murine model of MI was utilized to examine the effect of β-AR blockers on T-tubule remodeling following LV MI. We applied the in situ imaging of T-tubule structure from Langendorff-perfused intact hearts with laser scanning confocal microscopy. We found that MI caused remarkable T-tubule remodeling near the infarction border zone and moderate LV remodeling remote from the MI. Metoprolol and carvedilol administered 6 d after MI for 4 wk each increased the T-tubule integrity at the remote and border zones. At the molecular level, both β-AR blockers restored border and remote zone expression of junctophilin-2 (JP-2), which is involved in T-tubule organization and formation of the T-tubule/sarcoplasmic reticulum junctions. In contrast, β-AR blockers had no significant effects on caveolin-3 expression. In summary, our data show that β-AR antagonists can protect against T-tubule remodeling after MI, suggesting a novel therapeutic mechanism of action for this drug class. Preservation of JP-2 expression may contribute to the beneficial effects of metoprolol and carvedilol on T-tubule remodeling.

Effects of zoledronate in the repair of chronically infarcted rat myocardium

Zoledronate (Zol), one of the class of bisphophonate drugs, is commonly used to treat postmenopausal osteoporosis. Treatment of liposomal bisphosphonates has been shown to worsen myocardial infarct repair in an experimental model. The purpose of this study was to investigate the effect of Zol in the repair of chronically infarcted myocardium without liposomal encapsulation to mimic the clinical setting. Zol (20 μg/kg, a dose known to treat experimental osteoporosis in rats, n = 15) was administered subcutaneously to female Sprague-Dawley rats 1 day before coronary artery ligation. Rats receiving phosphate-buffered saline (n = 12) were used as controls. Left ventricular function, infarct size, and remodeling were studied at 4 weeks postinfarction. Zol pretreatment did not affect left ventricular ejection fraction in hearts with myocardial infarction (49.5 ± 1.4% in Zol; 50.6 ± 2.1% in phosphate-buffered saline). Infarct size was similar in Zol versus untreated hearts (34.2% ± 2.9% in Zol; 33.4% ± 2.9% in phosphate-buffered saline). Left ventricular cavity volume and circumference, infarct thickness, and expansion index were comparable between the groups. To investigate a potential effect of Zol on tissue macrophage infiltration after myocardial infarction, heart specimens were harvested 48 hours postinfarction and sections were immunostained with CD68 antibody, a macrophage-specific marker. Results of macrophage immunostaining revealed that the level of tissue macrophage infiltration was similar between groups. In conclusion, administration of Zol before myocardial infarction had no adverse effects on cardiac contractile function, infarct size, or remodeling. These results suggest that treatment of Zol given before the onset of myocardial infarction does not cause worsening of infarct repair.

Carvedilol-Afforded Protection against Daunorubicin-Induced Cardiomyopathic Rats In Vivo: Effects on Cardiac Fibrosis and Hypertrophy

Anthracyclines, most powerful anticancer agents, suffer from their cardiotoxic effects, which may be due to the induction of oxidative stress. Carvedilol, a third-generation, nonselective β-adrenoreceptor antagonist, possesses both reactive oxygen species (ROS) scavenging and ROS suppressive effects. It showed protective effects against daunorubicin- (DNR-) induced cardiac toxicity by reducing oxidative stress and apoptosis. This study therefore was designed to examine the effects of carvedilol on DNR-induced cardiomyopathic rats, focused on the changes of left ventricular function, cardiac fibrosis, and hypertrophy. Carvedilol increased survival rate, prevented systolic and diastolic dysfunction, and attenuated myocardial fibrosis and hypertrophy. DNR alone treated rats showed upregulated myocardial expression of ANP, PKC-α, OPN, and TGF-β1 and downregulation of GATA-4 in comparison with control, and treatment with carvedilol significantly reversed these changes. The results of the present study add the available evidences on the cardioprotection by carvedilol when associated with anthracyclines and explain the mechanisms underlying the benefits of their coadministration.

Divergent effects of losartan and metoprolol on cardiac remodeling, c-kit+ cells, proliferation and apoptosis in the left ventricle after myocardial infarction

There is strong evidence for the use of angiotensin converting enzyme inhibitors and beta-blockers to reduce morbidity and mortality in patients with myocardial infarction (MI), whereas the effect of angiotensin receptor blockers is less clear. We evaluated the effects of an angiotensin receptor blocker losartan and a beta-blocker metoprolol on left ventricular (LV) remodeling, c-kit+ cells, proliferation, fibrosis, apoptosis, and angiogenesis using a model of coronary ligation in rats. Metoprolol treatment for 2 weeks improved LV systolic function. In contrast, losartan triggered deleterious structural remodeling and functional deterioration of LV systolic function, ejection fraction being 41% and fractional shortening 47% lower in losartan group than in controls 2 weeks after MI. The number of c-kit+ cells as well as expression of Ki-67 was increased by metoprolol. Losartan-induced thinning of the anterior wall and ventricular dilation were associated with increased apoptosis and fibrosis, while losartan had no effect on the expression of c-kit or Ki-67. Metoprolol or losartan had no effect on microvessel density. These results demonstrate that beta-blocker treatment attenuated adverse remodeling via c-kit+ cells and proliferation, whereas angiotensin receptor blocker-induced worsening of LV systolic function was associated with increased apoptosis and fibrosis in the peri-infarct region.

Carvedilol treatment ameliorates acute coxsackievirus B3-induced myocarditis associated with oxidative stress reduction

Oxidative stress has been implicated in the pathogenesis of acute myocarditis. The imbalance between the occurrence of reactive oxygen species and the cellular antioxidant defense mechanism plays a key role in myocardial injury of viral myocarditis. Carvedilol, a nonselective beta-adrenoceptor antagonist with additional alpha1-adrenergic blocking and antioxidant properties, has been shown to be cardioprotective in experimental myocarditis. However, the expression of 4-hydroxy-2-nonenal (4-HNE), the most reliable marker of lipid peroxidation, has not been studied, and the antioxidative effects of carvedilol have not been investigated in the setting of acute viral myocarditis. This study was therefore designed to determine whether levels of lipid peroxides are elevated in the myocardium and whether carvedilol reduces the lipid peroxidation level and increases antioxidant enzyme activities. In a coxsackievirus B3 murine myocarditis model (Balb/c), effects of carvedilol and metoprolol on 14-day survival rate, myocardial histopathological changes, cardiac function, the expression of 4-HNE, virus titers, malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidases (GSH-Px) activities were studied. Lipid peroxidations including 4-HNE and MDA, were elevated in murine coxsackievirus-induced acute viral myocarditis. Carvedilol, but not metoprolol, improved survival, reduced lipid peroxidations including 4-HNE and MDA, and increased antioxidant enzyme activities including SOD and GSH-Px with amelioration of acute viral myocarditis. These results show that carvedilol but not metoprolol exerts some of its beneficial effects by inhibiting peroxidants.

Metoprolol treatment lowers thrombospondin-4 expression in rats with myocardial infarction and left ventricular hypertrophy

Thrombospondins are matrix proteins linked to extracellular matrix remodelling but their precise role in the heart is not known. In this study, we characterised left ventricular thrombospondin-1 and -4 expression in rats treated with a beta-blocker metoprolol during the remodelling process in response to pressure overload and acute myocardial infarction. Left ventricular thrombospondin-1 and thrombospondin-4 mRNA levels increased 8.4-fold (p < 0.001) and 7.3-fold (p < 0.001) post-infarction, respectively. Metoprolol infusion by osmotic minipumps (1.5 mg/kg/hr) for 2 weeks after myocardial infarction decreased thrombospondin-1 and thrombospondin-4 mRNA levels (55% and 50%, respectively), improved left ventricular function, and attenuated left ventricular remodelling with reduction of left ventricular atrial natriuretic peptide and brain natriuretic peptide gene expression. Thrombospondin-1 and -4 mRNA levels correlated positively with echocardiographic parameters of left ventricular remodelling as well as with atrial natriuretic peptide and brain natriuretic peptide gene expression. Moreover, there was a negative correlation between left ventricular ejection fraction and thrombospondin-1 mRNA levels. In 12-month-old spontaneously hypertensive rats with left ventricular hypertrophy, metoprolol decreased left ventricular thrombospondin-4 levels and attenuated remodelling while thrombospondin-1, atrial natriuretic peptide and brain natriuretic peptide mRNA levels as well as left ventricular function remained unchanged. In metoprolol-treated spontaneously hypertensive rats, thrombospondin-4 gene expression correlated with parameters of left ventricular remodelling, while no correlations between thrombospondins and natriuretic peptides were observed. These results indicate that thrombospondin-1 expression is linked exclusively to left ventricular remodelling process post-infarction while thrombospondin-4 associates with myocardial remodelling both after myocardial infarction and in hypertensive heart disease suggesting that thrombospondins may have unique roles in extracellular matrix remodelling process.

Distinctive effects of carvedilol in the non-infarct zone: remodelling of the ligated rat heart linked to oxidative stress

In this study, an experimental rat ligated heart model was used to observe the effect of treatment with carvedilol, metoprolol and metoprolol plus a highly selective alpha(1)-adrenergic blocking agent, bunazosin, after acute myocardial infarction (MI). Compared with an untreated MI group, all drug-treated groups demonstrated attenuation of inflammatory mediators, activation of nuclear factor-kappaB (NF-kappaB), and increased levels of mRNA and active protein for the collagenases matrix metallopeptidase (MMP)-8 and MMP-13 in the non-infarct zone of the ventricle, as well as inhibition of the increase of left ventricular end-diastolic pressure. Supplementation of metoprolol with bunazosin did not add greatly to the effects of metoprolol alone. Of the three drug treatments, carvedilol showed a uniquely potent antioxidant activity that may strengthen its capacity to inhibit oxidative stress, the release of inflammatory mediators and activation of NF-kappaB. This study may help provide a mechanistic explanation for the greater benefits shown by carvedilol compared with metoprolol in treating heart failure.

Suppression of collagen production in norepinephrine stimulated cardiac fibroblasts culture: differential effect of alpha and beta-adrenoreceptor antagonism

OBJECTIVES

Prolonged sympathetic activation is damaging to the heart and experimental norepinephrine (NE) infusion induces the deposition of myocardial collagen. This study investigated the effects of NE on collagen and transforming growth factor-beta1 (TGF-beta1) gene expression in rat cardiac fibroblasts (CF) culture, and compared the anti-fibrotic effect of alpha and beta (both selective and non-selective adrenergic receptor antagonists) receptors.

METHODS AND RESULTS

Rat CF were cultured in the presence of NE (0.01 to 100 muM) for 24 hours. Procollagen types I and III as well as TGF-beta1 gene expressions were measured by real-time quantitative PCR method. Collagen protein level was measured by Sirius red-based colorimetric method and Western blot analysis. The optimal dose of NE on fibrogenesis was 0.1 muM. Incubation for 24 hours increased procollagen I, III and TGF-beta1 gene expression by 1.35 +/- 0.23, 1.26 +/- 0.16 and 1.35 +/- 0.21 fold, respectively (all p < 0.05). The collagen protein was increased by both Sirius-red assay (0.120 +/- 0.03 vs 0.093 +/- 0.04 microg/total microg of protein, p < 0.05) and Western blot analysis (1.29 +/- 0.26 fold, p < 0.05), when compared with the control group. Addition of carvedilol (a non-selective beta-blocker with alpha-blockage activity) inhibited the effect of NE on procollagen I (0.64 +/- 0.17 vs 1.28 +/- 0.08 fold, p < 0.01), procollagen III gene (0.47 +/- 0.16 vs 1.45 +/- 0.29 fold, p < 0.01) and collagen protein expressions (0.99 +/- 0.12 vs 1.26 +/- 0.31 fold, p < 0.05, respectively). Doxazosin (an alpha-blocker) also inhibited the effect of NE on procollagen I (0.88 +/- 0.30 vs 1.28 +/- 0.08 fold, p < 0.01), procollagen III gene (0.64 +/- 0.13 vs 1.45 +/- 0.29 fold, p < 0.01) and collagen protein expression (0.90 +/- 0.11 vs 1.26 +/- 0.31 fold, p < 0.01 respectively). Such inhibitory effects were not seen in metoprolol (a beta1-selective blocker) and propranolol (a non-selective beta blocker). Furthermore, all the 4 drugs were unable to inhibit the NE induced TGF-beta1 gene over-expression.

CONCLUSIONS

In conclusion, NE increased collagen gene and protein expressions in CF culture. This effect is likely mediated through alpha-receptor as they were normalized by pretreatment with carvedilol and doxazosin, but not beta-blockers such as propranolol and metoprolol. Also, TGF-beta1 doesn't seem to play a role in carvedilol inhibition of NE induced fibrogenesis.

The effects of different beta-blockers on left-ventricular volume and function after primary coronary stenting in acute myocardial infarction

The beneficial effect of beta-blockers is reported in myocardial infarction (MI). This study compared the effects of propranolol and carvedilol on left-ventricular (LV) volume and function after acute MI. Serial echocardiographic studies were performed on acute MI patients who were treated with primary coronary stenting and medical treatment, including propranolol or carvedilol. Determinants of the changes in LV volume and function were identified by regression analyses. At 6 months, there was no significant difference in change in the LV end-diastolic volume between patients receiving 2 beta-blockers. The increase of LV ejection fraction was greater in patients receiving carvedilol. On multivariate analyses, it was found that the kind of beta-blocker had no significant influence on the changes in LV volume or ejection fraction, whereas gender and baseline LV ejection fraction were predictive of change in LV ejection fraction. Compared with propranolol, carvedilol did not have a significant benefit on LV remodeling or function after primary coronary stenting in acute MI.

Pleiotropic effects of cardiac drugs on healing post-MI. The good, bad, and ugly

Healing after myocardial infarction (MI) is a well-orchestrated time-dependent process that involves inflammation, tissue repair with extracellular collagen matrix (ECCM) deposition and scar formation, and remodeling of myocardial structure, matrix, vasculature, and function. Rapid early ECCM degradation followed by slow ECCM replacement and maturation during post-MI healing results in a prolonged window of enhanced vulnerability to adverse remodeling. Decreased ECCM results in adverse ventricular remodeling, dysfunction, and rupture. Inflammation, a critical factor in normal healing, if impaired results in adverse remodeling and rupture. Several therapeutic drugs prescribed after MI exert pleiotropic effects that suppress ECCM and inflammation during healing and may have good, bad, or ugly consequences. This article reviews the potential impact of pleiotropic effects of some prototypic cardiac drugs such as renin-angiotensin-aldosterone system (RAAS) inhibitors, statins, and thrombolytics during healing post-ST-segment-elevation MI (STEMI), with special focus on inflammation, ECCM and remodeling, and implications in the elderly.

Low coronary driving pressure early in the course of myocardial infarction is associated with subendocardial remodelling and left ventricular dysfunction

Subendocardial remodelling of the left ventricular (LV) non-infarcted myocardium has been poorly investigated. Previously, we have demonstrated that low coronary driving pressure (CDP) early postinfarction was associated with the subsequent development of remote subendocardial fibrosis. The present study aimed at examining the role of CDP in LV remodelling and function following infarction. Haemodynamics were performed in Wistar rats immediately after myocardial infarction (MI group) or sham surgery (SH group) and at days 1, 3, 7 and 28. Heart tissue sections were stained with HE, Sirius red and immunostained for alpha-actin. Two distinct LV regions remote to infarction were examined: subendocardium (SE) and interstitium (INT). Myocyte necrosis, leucocyte infiltration, myofibroblasts and collagen volume fraction were determined. Compared with SH, MI showed lower CDP and LV systolic and diastolic dysfunction. Necrosis was evident in SE at day 1. Inflammation and fibroplasia predominated in SE as far as day 7. Fibrosis was restricted to SE from day 3 on. Inflammation occurred in INT at days 1 and 3, but at a lower grade than in SE. CDP correlated inversely with SE necrosis (r = -0.65, P = 0.003, at day 1), inflammation (r = -0.76, P < 0.001, at day 1), fibroplasia (r = -0.47, P = 0.04, at day 7) and fibrosis (r = -0.83, P < 0.001, at day 28). Low CDP produced progressive LV expansion. Necrosis at day 1, inflammation at days 3 and 7, and fibroplasia at day 7 correlated inversely with LV function. CDP is a key factor to SE integrity and affects LV remodelling and function following infarction.

Combined use of ultra-short acting β-blocker esmolol and intravenous phosphodiesterase 3 inhibitor enoximone

In patients with impaired myocardial contractility associated with downregulation of the beta-receptors, compounds inhibiting phosphodiesterase (PDE) 3 may be useful to increase contractility. The PDE3 inhibitor enoximone has been shown to improve pump-function independent from the beta-receptor pathway. A simultaneous decrease in ventricular preload and afterload by vasodilation has led to the term 'inodilator'. Esmolol is the only available ultra-short acting intravenous beta-blocking agent. Due to its half-life of approximately 9 min, beta-blockade, and thus, heart rate, can easily be titrated. Esmolol appears to be a helpful tool to avoid myocardial ischemia (e.g., in the perioperative setting). As with all other beta-blockers, it has dose-dependent negative inotropic effects, and this limits its use in patients with severe heart failure showing low cardiac output. It seems reasonable that an intravenous combination of both approaches, enoximone-induced positive inotropy and esmolol-associated protection from myocardial ischemia, might offer advantages by producing beneficial hemodynamic effects and by compensating each other's limitations in a complementary way. In spite of some promising results, the place of a combination of enoximone and esmolol in the process of treating patients with (acute) heart failure showing low output is still not entirely clear, and needs further confirmation.

Antioxidant activity of carvedilol in cardiovascular disease

Oxidative and inflammatory stresses are cardinal in the pathogenesis of hypertension and atherosclerosis. Oxidative stress also leads to the induction of inflammation through the activation of proinflammatory transcription factors. Understanding the mechanisms leading to oxidative stress and the means of suppressing it are important in controlling complications related to atherogenesis, since oxidative and inflammatory stress are important in the pathogenesis of atherosclerosis. The failure of chemical antioxidants [which scavenge reactive oxygen species (ROS)], such as vitamins E and C, has led to further exploration of the ROS-suppressive effects of drugs used in the treatment of cardiovascular disease. Carvedilol has been shown to possess both ROS-scavenging and ROS-suppressive effects, and its use is associated with a reduction in oxidative stress. Furthermore, anti-inflammatory effects of carvedilol have now been described. Although further clinical investigations are required, these properties may contribute to the improvement in clinical outcomes observed with carvedilol.

Effect of β-Blockers on β3-Adrenoceptor Expression in Chronic Heart Failure

OBJECTIVES

To investigate the expression of beta(3)-adrenoceptors in rats with chronic heart failure, and to explore the effect of beta-blockers on beta(3)-adrenoceptor expression.

MATERIALS AND METHODS

Thirty-two male Wistar rats were divided into Sham (n = 10) and heart failure (n = 22) groups. The heart failure group was treated with normal saline (Heart Failure Control, n = 6), Metoprolol (n = 8) or Carvedilol (n = 8) for 3 months.

RESULTS

The left ventricular end systolic pressure (LVESP) and the absolute values of maximal rate of rise and fall of left ventricular pressure (+/-dP/dt max) in the heart failure group were lower than in the Sham group (P < 0.01), whereas the left ventricular end diastolic pressure (LVEDP) was higher (P < 0.01). The LVESP and dP/dtmax in the Carvedilol group were higher than the Metoprolol group whereas LVEDP was lower (P < 0.01). The left ventricular mass index (LVMI) in the Carvedilol group was less than the Metoprolol and Heart Failure Control groups (P < 0.01). The level of beta(3)-adrenoceptor expression in the study groups was significantly higher than the Sham group (P < 0.01). beta(3)-adrenoceptor expression in the Carvedilol group was lower than the Heart Failure Control and Metoprolol groups (P < 0.01).

CONCLUSION

beta(3)-adrenoceptor expression is increased in the failing ventricles in rats. Carvedilol is more effective than Metoprolol for improving the hemodynamics and in attenuating ventricular remodeling after heart failure. Carvedilol, rather than Metoprolol, diminishes beta(3)-adrenoceptor expression in the failing ventricles.

Urotensin-II receptor blockade with SB-611812 attenuates cardiac remodeling in experimental ischemic heart disease

It is now well established that urotensin-II (UII) levels are increased in several cardiovascular diseases. We previously demonstrated that UII and the UII receptor (UT) protein levels are significantly increased in the hearts of both humans and rats with congestive heart failure (CHF). We have also recently demonstrated that UII blockade, with a selective UII antagonist, improves heart function in a rat model of ischemic CHF. Here, we evaluated the attenuation of cardiac remodeling associated with UII antagonism in the same rat model of ischemic CHF. Animals were administered a specific UT receptor antagonist, SB-611812 (30 mg/kg/day, gavage), or vehicle 30 min prior to coronary artery ligation followed by daily treatment for 8 weeks. Myocardial interstitial fibrosis was analyzed by Masson's trichrome and picrosirius red staining. RT-PCR analysis was utilized for mRNA expression studies. We used Western blotting to assess levels of collagen types I and III. Mitogenic activity of UII on cultured neonatal cardiac fibroblasts was also evaluated. Following coronary ligation, SB-611812 significantly attenuated both myocardial and endocardial interstitial fibrosis, and reduced collagen type I:III ratio (P<0.01). UII induced proliferation of cardiac fibroblasts and this mitogenic effect was significantly inhibited with 1 microM of SB-611218 (P<0.05). We demonstrate here that selective blockade of UT reduces diastolic dysfunction by decreasing myocardial fibrosis post-coronary ligation in vivo, and inhibits UII-mediated fibroblast proliferation in vitro.

Carvedilol inhibits right ventricular hypertrophy induced by chronic hypobaric hypoxia

Right ventricular hypertrophy induced by chronic hypoxia is mainly due to a mechanical stress upon the ventricular wall secondary to pulmonary arterial hypertension. However, the hypoxic chronic activation of the sympathetic nervous system can contribute to the development of right ventricular hypertrophy either via myocardial adrenergic receptors and/or a vasoconstriction and remodeling of pulmonary arteries. To highlight the specific role of the sympathetic nervous system on hypoxia-induced right ventricular hypertrophy and particularly the efficiency of carvedilol, our study compared physiological, myocardial, and pulmonary arterial morphometric data in rats treated by alpha-(prazosin), or beta-(propranolol) or alphabeta-(carvedilol) antagonist and exposed to chronic hypobaric hypoxia (2 weeks at 380 mmHg barometric pressure). In chronic hypoxia, both systolic right ventricular pressure and Fulton's ratio (right/(left+septum) ventricular weight) were lower in rats treated by prazosin (-16.7 and -13.6%), propranolol (-28.6 and -12.7%) and carvedilol (-15.9 and -14.3%) respectively when compared to glucose (p<0.05). Surprisingly, prazosin was unable to reduce right ventricular hypertrophy induced by chronic hypoxia, whereas, left ventricular weight increased. Wall thickness index of pulmonary arteries increased in chronic hypoxia and was reduced by carvedilol. In conclusion, the hypoxia-induced activation of the adrenergic system participates in the development of right ventricular hypertrophy. Carvedilol is effective in reducing hypoxia-induced right ventricular hypertrophy, pulmonary arterial hypertension, and muscularization of pulmonary arteries.

Pharmacological Stimulation of β 2-adrenergic Receptors (β 2AR) Enhances Therapeutic Effectiveness of β 1AR Blockade in Rodent Dilated Ischemic Cardiomyopathy

BACKGROUND

We have reported that beta2 adrenoreceptor (beta2AR) stimulation is anti-apoptotic, and has strong beneficial effect on cardiac remodeling in an experimental model of post myocardial infarction chronic heart failure (CHF) in rats. Here we investigate whether the addition of chronic pharmacological beta2AR stimulation enhances the therapeutic effects of beta1AR blockade on cardiac remodeling in the same model.

METHODS AND RESULTS

Metoprolol, a beta1AR blocker, given alone (beta1) or in combination with beta2AR agonist, fenoterol (beta1beta2) were administered to rats via drinking water for 6 weeks, beginning 2 weeks following permanent coronary ligation. Progressive left ventricular (LV) remodeling of untreated animals, assessed by repeated echocardiography, occurred during the observation time, i.e., 42% and 25% increases in end-systolic and end-diastolic LV volumes respectively, 27% fall in ejection fraction, and 35% infarct expansion. Pressure-volume loop analyses at 2d and 8th post infarction weeks showed continuous deterioration of systolic and diastolic functions and arterio-ventricular mismatch. Histological evaluation at the end of 8 weeks revealed the MI expansion and hypertrophy of cardiomyocytes. beta1beta2 prevented LV remodeling, MI expansion and cardiomyocytes hypertrophy to a greater degree than beta1, due, in large part, to a vasodilatory effect of beta2AR stimulation and thus improvement of arterio-ventricular mismatch. The abnormal diastolic performance improved only in beta1beta2. beta1beta2 treatment reduced myocardial apoptosis throughout myocardium, but beta1 reduced apoptosis only in the areas remote from MI.

CONCLUSION

The therapeutic effects of chronic beta1AR blockade on cardiac remodeling of heart failure are enhanced and extended when supplemented with beta2AR stimulation.

Left ventricular diastolic function improvement by carvedilol therapy in advanced heart failure

Carvedilol treatment in chronic heart failure (CHF) patients has been demonstrated to reduce mortality by improving cardiac systolic function and reducing left ventricular adverse remodeling. However, the effects of the drug on left ventricular (LV) filling are less studied. In this study we evaluated early and long-term diastolic cardiac modifications by an echo-Doppler method during carvedilol therapy in patients with advanced CHF and pseudonormal or restrictive filling pattern. We studied 58 patients with severe but stable CHF (39 in class NYHA III and 19 in IV) having systolic and diastolic dysfunction caused by idiopathic or ischemic cardiomyopathy. Thirty-two patients were randomized to receive previous treatment plus carvedilol (group 1) and 26 continued standard therapy (group 2). In all subjects we evaluated LV volumes, LV mass, LV ejection fraction (EF), and the following transmitral filling parameters: early wave (E), atrial wave (A), E/A ratio, deceleration time (DT), and isovolumetric releasing time (IVRT). After 4 months of therapy, the carvedilol group showed a significant increase of A wave (P < 0.001), DT (P < 0.0001), IVRT (P < 0.0001), and a significant reduction of E/A ratio (P < 0.0005) with respect to group 2. Further improvement was observed at 12 months (A P < 0.0005; DT P < 0.00002; IVRT P < 0.000004; E/A P < 0.0008), although an E wave reduction was observed in group 1 with respect to controls (P < 0.001). Moreover, after 1 year of follow-up a reduction of systolic volume (P < 0.001) and pulmonary pressure (P < 0.0001) and consequent increase of EF (P < 0.001) was observed in the carvedilol group. Carvedilol treatment improved diastolic function in CHF with severe diastolic and systolic impairment at early time, converting a restrictive or pseudonormal filling pattern into an altered pattern. These changes remained significant after 1 year of therapy together with improvement in systolic function.

Effects of carvedilol on cardiac cytokines expression and remodeling in rat with acute myocardial infarction

OBJECTIVE

A number of observations suggest that cytokines may be important modulators in the ventricular remodeling process. It is unclear whether carvedilol modulates myocardial pro-inflammatory and anti-inflammatory cytokines expression. We hypothesized that carvedilol could improve ventricular remodeling partly through the modulation of cytokines. The goal of this study was to evaluate the effects of carvedilol on cardiac cytokines expression as well as on myocardial and extracellular matrix remodeling in rats with acute myocardial infarction.

METHODS

Rats with AMI induced by left anterior descending branch ligation were randomized to carvedilol and control group which were further compared to sham-operated group. We studied the effects of 4-weeks therapy with carvedilol starting 24 h after infarction on 1) hemodynamics, 2) tissue weights, 3) myocardial cytokines (TNF-alpha, IL-1beta, IL-6, IL-10 and TGF-beta1) expression by semi-quantitative RT-PCR and immunoblotting, 4) matrix metalloproteinases activity by gelatin zymography, 5) collagen expression by immunohistochemistry, 6) myocardium fetal gene (alpha and beta myosin heavy chain) expression.

RESULTS

Treatment with carvedilol 1) reduced the pro-inflammatory cytokines and fibrogenic cytokine TGF-beta1 levels in myocardium and was associated with the amelioration of the elevated left ventricular diastolic pressure. 2) increased anti-inflammatory cytokine, IL-10 protein expression. 3) reduced matrix metalloproteinases-2 and matrix metalloproteinases-9 activity 4) reduced myocardial collagens 5) did not modify fetal gene re-expression.

CONCLUSION

Pro-inflammatory, anti-inflammatory and fibrogenic cytokines are all involved in the process of post-infarction myocardial remodeling. One mechanism underlying the beneficial effects of carvedilol on post-infarction myocardial remodeling may be modulation of the balance between pro- and anti-inflammatory cytokines as well as fibrogenic cytokines and extracellular matrix (ECM) remodeling.

Effect of β-Blockers on Cardiac Function and Calcium Handling Protein in Postinfarction Heart Failure Rats

OBJECTIVES

The normal expression of Ca2+-handling protein is critical for efficient myocardial function. The present study was designed to test the hypothesis that beta-blocker treatment may attenuate left ventricular (LV) remodeling and cardiac contractile dysfunction in the failing heart, which may be associated with alterations of Ca2+-handling protein

METHODS

We investigated the change of LV remodeling and function in a rat model of heart failure due to myocardial infarction (MI) with or without carvedilol (30 mg/kg/d) or metoprolol (60 mg/kg/d) treatment for 6 weeks (n = 9 in the MI plus carvedilol group, and n = 8 in every other group). The expression of messenger RNA and proteins of sarcoplasmic reticulum Ca2+-adenosine triphosphatase (SERCA) and phospholamban in cardiomyocytes of all rats were also measured

RESULTS

There was significant LV remodeling and cardiac contractile dysfunction in MI rats. The messenger RNA and protein expression of SERCA were down-regulated (p < 0.01), but the expression of phospholamban messenger RNA and protein were up-regulated (p < 0.01) in MI rats compared to sham-operated rats. After the treatment with beta-blockers, LV remodeling and function were clearly improved. Carvedilol was better in attenuating the weight of the LV and the relative weight of the right ventricle than metoprolol (p < 0.05). beta-Blockers restored the low expression of SERCA (p < 0.05) but showed no effect on phospholamban expression (p > 0.05). Moreover, carvedilol induced a more significant improvement of SERCA expression than metoprolol (p < 0.05)

CONCLUSIONS

Beta-blockers are effective in preventing LV remodeling and cardiac contractile dysfunction in the failing heart. The molecular mechanism may be related to normalization of SERCA expression.

Do metoprolol and carvedilol have equivalent effects on diurnal heart rate in patients with chronic heart failure?

BACKGROUND

Carvedilol exerted a greater reduction in mortality than metoprolol tartrate in the Carvedilol or Metoprolol European Trial (COMET). However, it is unclear if the degree and time course of beta1-blockade during a 24-h period was similar with each agent at the doses used. Therefore we analyzed 24-h ECG Holter recordings from a study which compared the long-term clinical efficacy of metoprolol tartrate to carvedilol in chronic heart failure patients using the same dosing regimen as in COMET.

METHODS AND RESULTS

Fifty-one patients with chronic heart failure with a mean LVEF 26+/-1.8% were randomized in a double-blind fashion to receive metoprolol tartrate 50 mg bid or carvedilol 25 mg bid. 24-h ECG monitoring (Holter) was performed at baseline, 12 weeks and 1 year. Adequate quality recordings for analysis were obtained from 43 subjects at baseline, 42 at 12 weeks and 29 subjects at 1 year. Both drugs produced a fall in average 24-h heart rate from baseline at 12 weeks and at 1 year: metoprolol 88+/-3 to 71+/-2 and 69+/-3 bpm; carvedilol 83+/-3 to 70+/-2 and 70+/-3 bpm respectively (all p<0.001). The pattern of suppression of heart rate during the 24-h period was similar for both drugs.

CONCLUSION

Metoprolol tartrate 50 mg bid and carvedilol 25 mg bid had similar effects on 24-h heart rate. This result suggests that the degree of beta1-blockade produced by these two drugs in these doses is comparable and the superior survival effect of carvedilol compared to metoprolol seen in COMET is likely to be due to actions of carvedilol other than beta1-blockade.

Cardiovascular and survival effects of sympatho-inhibitors in adriamycin-induced cardiomyopathy in rats

Adriamycin (ADR) is a widely used drug for the treatments of cancers. This study evaluates the effects of moxonidine and metoprolol on cardiac hemodynamics and survival in ADR-induced left ventricular dysfunction (total dose of 20 mg/kg in a 4-week regimen). Rats were treated with the centrally acting I(1)R agonist sympatho-inhibitor, moxonidine, or with the non-selective beta-adrenergic antagonist, metoprolol, during 1 month or until death. Treatments began 1 week after the onset of the ADR administration. Low doses (0.5 and 1 mg/kg/day) of moxonidine and metoprolol (10 mg/kg/day) improved cardiovascular function. High doses of moxonidine (3 mg/kg/day) and metoprolol (150 mg/kg/day) were cardiodepressive. Moxonidine and metoprolol both failed to improve survival. These data indicate that a treatment with these sympatho-inhibitors can reduce the left ventricular dysfunction induced by ADR. Moreover, these cardioprotective effects where obtained even when ADR was used at a dose regimen usually employed for its antineoplastic effects in rodents. Nevertheless, in this particular cardiomyopathy, we did not find any association between improvements of functional parameters and survival whatever the drug and the dose used. This problem points out the difficulty to prevent, at least with sympatho-inhibitory drugs alone, the mortality linked to the chronic cardiotoxicity of ADR.

The prophylactic use of the beta-blocker esmolol in combination with phosphodiesterase III inhibitor enoximone in elderly cardiac surgery patients

We assessed the influence of the prophylactic use of a combination of the IV beta-adrenergic blocker, esmolol, and the phosphodiesterase III inhibitor, enoximone, on postbypass hemodynamic status, inflammation, and endothelial and organ function in a prospective, randomized, placebo-controlled study in 42 patients aged >65 yr undergoing aortocoronary bypass grafting. In 21 patients, esmolol (aim: heart rate <70 bpm) plus enoximone (initial bolus of 0.5 mg/kg followed by a continuous infusion of 2.5 microg x kg(-1) x min(-1)) was started after induction of anesthesia and continued until the morning of the first postoperative day; another 21 patients received saline solution as placebo. Hemodynamics, splanchnic perfusion (gastric-arterial CO(2) gap), liver function (glutathione transferase-alpha plasma levels), renal function (creatinine clearance, urine concentrations of N-acetyl-beta-D-glucosaminidase), myocardial ischemia (creatine-kinase MB and troponin T plasma levels), inflammation (elastase, interleukin-6 and -8 plasma levels), and endothelial integrity (adhesion molecules plasma levels) were assessed at baseline, before and after cardiopulmonary bypass (CPB), and in the intensive care unit until the first postoperative day. Catecholamine requirements were significantly less in the treated than in the nontreated patients. Heart rate was significantly slower, cardiac index was higher, and gastric-arterial CO(2) gap was significantly lower in the treatment group. Troponin T, beta-N-acetyl-beta-D-glucosaminidase, glutathione transferase-alpha, and soluble adhesion molecules increased significantly in the untreated control, but remained almost normal in the esmolol+enoximone patients. Inflammatory responses (elastase/interleukins) were attenuated by esmolol+enoximone. We conclude that, in comparison to an untreated control, the prophylactic use of a combination of esmolol and enoximone in elderly patients undergoing cardiac surgery with cardiopulmonary bypass resulted in overall beneficial effects on postbypass hemodynamic status, organ function, inflammatory response, and endothelial integrity.

Beneficial Effects of Chronic Pharmacological Manipulation of β-Adrenoreceptor Subtype Signaling in Rodent Dilated Ischemic Cardiomyopathy

Background— Studies in isolated cardiac myocytes have demonstrated that signaling via specific β 1 -adrenergic receptor subtypes (β 1 ARs) promotes but that signaling via β 2 ARs protects from cell death. We hypothesized that prolonged β 2 AR stimulation or β 1 AR blockade would each protect myocytes from death and thereby ameliorate cardiac remodeling in chronic heart failure.

Methods and Results— A large myocardial infarction (MI) induced in rats by coronary artery ligation resulted in a dilated cardiomyopathy (DCM) characterized by infarct expansion and a progressive increase in left ventricular (LV) end-diastolic volume, accompanied by a reduction in ejection fraction (EF), as assessed by repeated echocardiography. Pressure-volume analysis at 8 weeks after ligation showed that diastolic stiffness (Eed) and arterial elastance (Ea) were increased, end-systolic elastance (Ees) was decreased, and arterioventricular (AV) coupling (Ea/Ees) had deteriorated. Apoptosis was present in both peri-infarct and remote myocardium. Chronic (6-week) administration of the β 2 AR agonists fenoterol or zinterol, starting at 2 weeks after MI, reduced the extent of LV dilation, infarct expansion, and EF decline. The β 1 AR blocker metoprolol did not affect the former and preserved EF to a lesser extent than did the β 2 AR agonists. At 8 weeks after ligation, apoptosis was reduced by all drugs but to a greater extent by β 2 AR agonists than by the β 1 AR blocker. Both β 2 AR agonists and the β 1 AR blocker improved AV coupling, the former mainly by reducing Ea and the latter mainly by increasing Ees. Only the β 2 AR agonists reduced the Eed and the MI size by reducing infarct expansion.

Conclusions— These results provide proof of concept for the efficacy of chronic β 2 AR stimulation in this DCM model.

Norepinephrine-induced changes in cardiac transforming growth factor-beta isoform expression pattern of female and male rats

Transforming growth factor-beta (TGF-beta) is a ubiquitous growth-regulating protein with an essential role in tissue repair and formation of extracellular matrix (ECM). To better understand the role of different isoforms of TGF-beta in the cardiac remodeling process induced by norepinephrine (NE), the expression of TGF-beta1, TGF-beta2, and TGF-beta3 was studied and compared with the expression of collagen. NE (0.1 mg/kg. h) was intravenously infused in female and male Sprague-Dawley rats for several time periods, and freshly obtained ventricular myocardium after 1 day was dissociated into myocyte and nonmyocyte fractions. Prazosin (0.1 mg/kg x h) and metoprolol (1 mg/kg. h) were used to block alpha- and beta-adrenoceptors, respectively. After NE infusion, the three isoforms of TGF-beta were differentially induced as far as the magnitude and the time course is concerned. The increased expression of TGF-beta2 started earlier with a maximum after 12 hours and was more pronounced (10-fold elevation) than that of the other two isoforms, with a clear specificity for the left ventricle in female hearts. This specificity was also seen in male rats with 16-fold elevation of TGF-beta2 after 1 day of NE-stimulation. The increase of TGF-beta2 was significant only in the myocyte fraction obtained from female as well as from male hearts. The expression of the mRNA of all TGF-beta isoforms of collagen type I and type III, and of the matrix metalloproteinase (MMP)-2 and its inhibitor TIMP-2 was reduced predominantly by alpha-adrenoceptor blockade with prazosin. The increase in TGF-beta isoforms correlated with that of the mRNA expression of collagens, MMP-2 and TIMP-2.