Inhibitory effects of carvedilol on calcium channels in vascular smooth muscle cells

Mechanistic insights into carvedilol's potential protection against doxorubicin-induced cardiotoxicity

Doxorubicin (DOX) is an anthracycline chemotherapy drug widely employed in the treatment of various cancers, known for its potent antineoplastic properties but often associated with dose-dependent cardiotoxicity, limiting its clinical use. This review explores the complex molecular details that determine the heart-protective effectiveness of carvedilol in relation to cardiotoxicity caused by DOX. The harmful effects of DOX on heart cells could include oxidative stress, DNA damage, iron imbalance, disruption of autophagy, calcium imbalance, apoptosis, dysregulation of topoisomerase 2-beta, arrhythmogenicity, and inflammatory responses. This review carefully reveals how carvedilol serves as a strong protective mechanism, strategically reducing each aspect of cardiac damage caused by DOX. Carvedilol's antioxidant capabilities involve neutralizing free radicals and adjusting crucial antioxidant enzymes. It skillfully manages iron balance, controls autophagy, and restores the calcium balance essential for cellular stability. Moreover, the anti-apoptotic effects of carvedilol are outlined through the adjustment of Bcl-2 family proteins and activation of the Akt signaling pathway. The medication also controls topoisomerase 2-beta and reduces the renin-angiotensin-aldosterone system, together offering a thorough defense against cardiotoxicity induced by DOX. These findings not only provide detailed understanding into the molecular mechanisms that coordinate heart protection by carvedilol but also offer considerable potential for the creation of targeted treatment strategies intended to relieve cardiotoxicity caused by chemotherapy.

Multitargeting in cardioprotection: An example of biaromatic compounds

A multitarget drug design approach is actively developing in modern medicinal chemistry and pharmacology, especially with regard to multifactorial diseases such as cardiovascular diseases, cancer, and neurodegenerative diseases. A detailed study of many well-known drugs developed within the single-target approach also often reveals additional mechanisms of their real pharmacological action. One of the multitarget drug design approaches can be the identification of the basic pharmacophore models corresponding to a wide range of the required target ligands. Among such models in the group of cardioprotectors is the linked biaromatic system. This review develops the concept of a "basic pharmacophore" using the biaromatic pharmacophore of cardioprotectors as an example. It presents an analysis of possible biological targets for compounds corresponding to the biaromatic pharmacophore and an analysis of the spectrum of biological targets for the five most known and most studied cardioprotective drugs corresponding to this model, and their involvement in the biological effects of these drugs.

Mechanism of carvedilol induced action potential and calcium alternans

Carvedilol is a nonspecific β-blocker clinically used for the treatment of cardiovascular diseases but has also been shown to have profound effects on excitation-contraction coupling and Ca signaling at the cellular level. We investigate the mechanism by which carvedilol facilitates Ca transient (CaT) and action potential duration (APD) alternans in rabbit atrial myocytes. Carvedilol lowered the frequency threshold for pacing-induced CaT alternans and facilitated alternans in a concentration-dependent manner. Carvedilol prolonged the sarcoplasmic reticulum (SR) Ca release refractoriness by significantly increasing the time constant τ of recovery of SR Ca release; however, no changes in L-type calcium current recovery from inactivation or SR Ca load were found after carvedilol treatment. Carvedilol enhanced the degree of APD alternans nearly two-fold. Carvedilol slowed the APD restitution kinetics and steepened the APD restitution curve at the pacing frequency (2 Hz) where alternans were elicited. No effect on the CaT or APD alternans ratios was observed in experiments with a different β-blocker (metoprolol), excluding the possibility that the carvedilol effect on CaT and APD alternans was determined by its β-blocking properties. These data suggest that carvedilol contributes to the generation of CaT and APD alternans in atrial myocytes by modulating the restitution of CaT and APD.

Ischemia and no obstructive coronary arteries (INOCA): A narrative review

Myocardial ischemia with no obstructive coronary arteries (INOCA) is a chronic coronary syndrome condition that is increasingly being recognized as a substantial contributor to adverse cardiovascular mortality and outcomes, including myocardial infarction and heart failure with preserved ejection fraction (HFpEF). While INOCA occurs in both women and men, women are more likely to have the finding of INOCA and are more adversely impacted by angina, with recurrent hospitalizations and a lower quality of life with this condition. Abnormal epicardial coronary vascular function and coronary microvascular dysfunction (CMD) have been identified in a majority of INOCA patients on invasive coronary function testing. CMD can co-exist with obstructive epicardial coronary artery disease (CAD), diffuse non-obstructive epicardial CAD, and with coronary vasospasm. Epicardial vasospasm can also occur with normal coronary arteries that have no atherosclerotic plaque on intravascular imaging. While all predisposing factors are not clearly understood, cardiometabolic risk factors, and endothelium dependent and independent mechanisms that increase oxidative stress and inflammation are associated with microvascular injury, CMD and INOCA. Cardiac autonomic dysfunction has also been implicated in abnormal vasoreactivity and persistent symptoms. INOCA is under-recognized and under-diagnosed, partly due to the heterogenous patient populations and mechanisms. However, diagnostic testing methods are available to guide INOCA management. Treatment of INOCA is evolving, and focuses on cardiac risk factor control, improving ischemia, reducing atherosclerosis progression, and improving angina and quality of life. This review focuses on INOCA, relations to HFpEF, available diagnostics, current and investigational therapeutic strategies, and knowledge gaps in this condition.

Effect of carvedilol on arteriovenous graft primary patency

BACKGROUND

The major mechanisms of arteriovenous graft (AVG) failure due to intimal hyperplasia (IH) are smooth muscle cell proliferation and inflammation. Therefore, carvedilol may improve AVG primary patency because of its anti-proliferative and anti-inflammatory activities.

METHODS

The data of end-stage renal disease patients receiving regular hemodialysis were collected from the National Health Insurance Research database. The end point was the first percutaneous transluminal angioplasty (PTA) for AVG failure or death during a follow-up period of two years or the end of 2013. The analysis was calculated with Cox proportional hazard model.

RESULTS

There were 3028 patients treated with carvedilol and 13,704 patients not treated with carvedilol. According to a univariate analysis, the carvedilol group was younger, received more anti-hypertensive medications and platelet aggregation inhibitors, and had higher rates of diabetes mellitus and hyperlipidemia but had lower rates of hypotension and smoking. According to a multivariate analysis, after controlling for covariates, the use of carvedilol for more than 84 days reduced the probability of a first PTA for AVG failure by 9% compared with no use of carvedilol (p = 0.021), but the use of carvedilol for 1 to 84 days did not.

CONCLUSION

The results of this study indicate that the use of carvedilol for more than 84 days improves the primary patency of AVGs, but the use of carvedilol for less than 84 days does not.

Effect of carvedilol on atrial excitation-contraction coupling, Ca2+ release, and arrhythmogenicity

Carvedilol is an FDA-approved β-blocker commonly used for treatment of high blood pressure, congestive heart failure, and cardiac tachyarrhythmias, including atrial fibrillation. We investigated at the cellular level the mechanisms through which carvedilol interferes with sarcoplasmic reticulum (SR) Ca²⁺ release during excitation-contraction coupling (ECC) in single rabbit atrial myocytes. Carvedilol caused concentration-dependent (1-10 µM) failure of SR Ca²⁺ release. Failure of ECC and Ca²⁺ release was the result of dose-dependent inhibition of voltage-gated Na⁺ (I_Na) and L-type Ca²⁺ (I_Ca) currents that are responsible for the rapid depolarization phase of the cardiac action potential (AP) and the initiation of Ca²⁺-induced Ca²⁺ release from the SR, respectively. Carvedilol (1 µM) led to AP duration shortening, AP failures, and peak I_Na inhibition by ~80%, whereas I_Ca was not markedly affected. Carvedilol (10 µM) blocked I_Na almost completely and reduced I_Ca by ~40%. No effect on Ca²⁺-transient amplitude, I_Ca, and I_Na was observed in control experiments with the β-blocker metoprolol, suggesting that the carvedilol effect on ECC is unlikely the result of its β-blocking property. The effects of carvedilol (1 µM) on subcellular SR Ca²⁺ release was spatially inhomogeneous, where a selective inhibition of peripheral subsarcolemmal Ca²⁺ release from the junctional SR accounted for the cell-averaged reduction in Ca²⁺-transient amplitude. Furthermore, carvedilol significantly reduced the probability of spontaneous arrhythmogenic Ca²⁺ waves without changes of SR Ca²⁺ load. The data suggest a profound antiarrhythmic action of carvedilol in atrial myocytes resulting from an inhibitory effect on the SR Ca²⁺ release channel.NEW & NOTEWORTHY Here we show that the clinically widely used β-blocker carvedilol has profound effects on Ca²⁺ signaling and ion currents, but also antiarrhythmic effects in adult atrial myocytes. Carvedilol inhibits sodium and calcium currents and leads to failure of ECC but also prevents spontaneous Ca²⁺ release from cellular sarcoplasmic reticulum (SR) Ca²⁺ stores in form of arrhythmogenic Ca²⁺ waves. The antiarrhythmic effect occurs by carvedilol acting directly on the SR ryanodine receptor Ca²⁺ release channel.

Metabolomic profiling of cellular responses to carvedilol enantiomers in vascular smooth muscle cells

Carvedilol is a non-selective β-blocker indicated in the treatment of hypertension and heart failure. Although the differential pharmacological effects of individual Carvedilol enantiomer is supported by preceding studies, the cellular response to each enantiomer is not well understood. Here we report the use of GC-MS metabolomic profiling to study the effects of Carvedilol enantiomers on vascular smooth muscle cells (A7r5) and to shed new light on molecular events underlying Carvedilol treatment. The metabolic analysis revealed alternations in the levels of 8 intracellular metabolites and 5 secreted metabolites in A7r5 cells incubated separately with S- and R-Carvedilol. Principal component analysis of the metabolite data demonstrated the characteristic metabolic signatures in S- and R-Carvedilol-treated cells. A panel of metabolites, including L-serine, L-threonine, 5-oxoproline, myristic acid, palmitic acid and inositol are closely correlated to the vascular smooth muscle contraction. Our findings reveal the differentiating metabolites for A7r5 cells incubated with individual enantiomer of Carvedilol, which opens new perspectives to employ metabolic profiling platform to study chiral drug-cell interactions and aid their incorporation into future improvement of β-blocker therapy.

A hybrid approach to advancing quantitative prediction of tissue distribution of basic drugs in human

A general toxicity of basic drugs is related to phospholipidosis in tissues. Therefore, it is essential to predict the tissue distribution of basic drugs to facilitate an initial estimate of that toxicity. The objective of the present study was to further assess the original prediction method that consisted of using the binding to red blood cells measured in vitro for the unbound drug (RBCu) as a surrogate for tissue distribution, by correlating it to unbound tissue:plasma partition coefficients (Kpu) of several tissues, and finally to predict volume of distribution at steady-state (V(ss)) in humans under in vivo conditions. This correlation method demonstrated inaccurate predictions of V(ss) for particular basic drugs that did not follow the original correlation principle. Therefore, the novelty of this study is to provide clarity on the actual hypotheses to identify i) the impact of pharmacological mode of action on the generic correlation of RBCu-Kpu, ii) additional mechanisms of tissue distribution for the outlier drugs, iii) molecular features and properties that differentiate compounds as outliers in the original correlation analysis in order to facilitate its applicability domain alongside the properties already used so far, and finally iv) to present a novel and refined correlation method that is superior to what has been previously published for the prediction of human V(ss) of basic drugs. Applying a refined correlation method after identifying outliers would facilitate the prediction of more accurate distribution parameters as key inputs used in physiologically based pharmacokinetic (PBPK) and phospholipidosis models.

Effect of carvedilol on coronary flow reserve in patients with hypertensive left-ventricular hypertrophy

OBJECTIVE

Patients with hypertensive left-ventricular hypertrophy (LVH) have lower coronary flow reserve (CFR). Whether carvedilol can improve CFR of patients with hypertensive LVH is unknown. We aimed to investigate the effects of carvedilol on CFR in patients with hypertensive LVH.

METHODS

Sixty-three patients were randomly divided into two groups for treatment with carvedilol or metoprolol. The peak diastolic coronary flow velocity in the left anterior descending coronary artery at rest and at maximal vasodilation with dipyridamole infusion was recorded by transesophageal echocardiography (TEE), then CFR was calculated at baseline and at the end of 6 months of therapy. Left-ventricular mass index (LVMI) was calculated by 2-D echocardiography. Endothelium-dependent and -independent reactivity of the brachial artery was measured. Levels of plasma endothelin-1 (ET1), nitric oxide (NO) and other metabolites were monitored and analyzed before and after 6-month therapy.

RESULTS

Both blood pressure and heart rate decreased significantly in the two treatment groups after therapy (p<0.05). With carvedilol treatment, LVMI was lower (p<0.05), endothelium function of the brachial artery was higher (p<0.05), and peak diastolic coronary flow velocity at rest and at maximal vasodilation after dipyridamole infusion was significantly higher (p<0.05) than with metoprolol treatment, which led to a significantly higher CFR (p<0.05). Changes in CFR and LVMI with carvedilol treatment were inversely correlated (R(2)=0.474, p=0.036). With carvedilol treatment, plasma level of ET-1 was lower, but that of NO was significantly higher than with metoprolol treatment (both p<0.05).

CONCLUSIONS

The CFR of patients with hypertensive LVH but not coronary artery disease could increase with 6-month carvedilol therapy.

Proteomic profiling of cellular responses to Carvedilol enantiomers in vascular smooth muscle cells by iTRAQ-coupled 2-D LC-MS/MS

Carvedilol is a third-generation beta-blocker, with the S-enantiomer being more active than the R-enantiomer. Clinically, it has been used in the treatment of hypertension, congestive heart failure and angina pectoris. Each enantiomer of Carvedilol exhibits differential pharmacological effects. However, the cellular effects of individual enantiomer are not well understood. To gain insights into how each enantiomer affects cells, we analysed differential protein expression levels in vascular smooth muscle cells (A7r5) incubated separately with S- and R-Carvedilol by iTRAQ-coupled 2-D LC-MS/MS approach. Thirteen proteins were identified with statistically significant changes in cells incubated with S-Carvedilol, while the changes of most proteins incubated with R-Carvedilol were less significant. Among these proteins, actin in aortic smooth muscle (ACTA2), calmodulin, S100-A6, S100-A10, S100-A11, thioredoxin, lactadherin and heat-shock protein 105 kDa were found to be closely relevant with the clinical effects of Carvedilol. Furthermore, the changes in protein levels were validated by Western blot. Our findings thus provided molecular evidence on a comprehensive protein profile on Carvedilol-cell interaction, which may shed new light in molecular events underlying Carvedilol treatment.

Calcium-independent tacrine-induced relaxation of rat gastric corpus smooth muscles

Tacrine, a non-competitive reversible acetylcholinesterase and butyrylcholineserase inhibitor, caused a concentration-dependent tonic contraction of gastric smooth muscle preparations in the concentration range 1 × 10−7 mol/L – 1 × 10−5 mol/L, whereas concentrations higher than 2 × 10−5 mol/L induced a biphasic effect; a short-time contraction was followed by a prolonged relaxation. To shed some light on the mechanism underlying this untypical relaxation, the amplitude of mechanical reactions caused by tacrine were compared with those of tacrine in the presence of atropine, ipratropium, metrifonate, TTX, nifedipine, D-600, caffeine, apamin, and charybdotoxin. The results obtained revealed that the relaxation was neither cholinergic in nature, nor mediated by the influence of the drug on intramural neuronal structures. It was not influenced by processes inducing changes in cytosolic Ca2+ levels. This assumption was confirmed by experiments with permeabilized muscle preparations that were pre-contracted in a solution with pCa 5.5. Tacrine relaxed the smooth muscles in spite of the constant intracellular Ca2+ concentration resulting from the permeabilization. These findings argue that tacrine at concentrations higher than 2 × 10−5 mol/L has a desensitizing effect on the contractile apparatus of gastric corpus smooth muscle preparations towards Ca2+.

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.

Carvedilol blocks cardiac KATP and KG but not IK1 channels by acting at the bundle-crossing regions

We examined the effects of carvedilol on cardiac inwardly rectifying K(+) (Kir) channels, i.e., ATP-sensitive (K(ATP)), G-protein-activated (K(G)) and background (I(K1)) Kir channels. We found that carvedilol effectively inhibits K(ATP) and K(G), but not I(K1) channels. Carvedilol inhibits K(ATP) channels reconstituted in HEK293 cells with Kir6.2 lacking the C-terminal 26 amino acids (Kir6.2DeltaC26), suggesting that carvedilol acts in the channel pore. A sequence comparison of the three channels revealed that a cysteine residue, C166, in the inner helix of Kir6.2 is conserved in both Kir6.xs (K(ATP)) and Kir3.xs (K(G)), but not in Kir2.xs (I(K1)). The mutation of this residue (C166A) made Kir6.2DeltaC26 resistant to the drug. Homology modeling and docking simulation suggested that interaction between carvedilol and the pore could be located at the cytosolic portion of the inner helix (bundle-crossing region) containing C166. This study shows that carvedilol blocks specific groups of Kir channels by interacting with the bundle-crossing region.

Predictors of stable outcome in treating chronic heart failure patients with carvedilol

Carverdilol has a variable outcome in treating patients with chronic heart failure. This prospective single-center study evaluated the predictors of clinical variables in determining favorable outcomes in treating chronic heart failure patients with carvedilol. The relation between clinical variables and maintenance doses of carvedilol was also determined. Seventy chronic heart failure patients (mean age, 62.2 years, 50 males and 20 females) with a left ventricular ejection fraction < 35% and functional class II-III were enrolled in the study. The patients were clinically followed-up for at least 24 months. Patients were considered to have a favorable outcome if they had no decreases in functional class or quality-of-life score, an increase in left ventricular ejection fraction>5%, were not admitted to hospital due to worsening heart failure, and free of cardiac mortality. Patients with favorable outcomes had a younger age (P = 0.021), higher baseline systolic blood pressure (P = 0.080), better baseline functional class (P = 0.001), and a higher tolerated dose of carvedilol (P = 0.026) than those in the unfavorable group. In this primarily Chinese cohort of chronic heart failure patients, those with favorable outcomes were likely to be young, have a high baseline systolic blood pressure, and good baseline functional class.