Ventricular arrhythmias (VAs) are the leading cause of sudden cardiac death in patients with myocardial infarction (MI). We sought to compare effects of renal denervation (RDN) and metoprolol on VAs after MI. Fifty-four male Sprague-Dawley rats underwent ligation of left anterior descending coronary artery to induce MI, while 6 rats served as Control. Metoprolol was given 20 mg/kg/day for 5 weeks after MI surgery. RDN/Sham-RDN procedure was performed at 1 week after MI. At 5 weeks after MI, electrical programmed stimulation (EPS) was performed in all groups for evaluation of VAs. After EPS, heart and kidneys were harvested. Compared with MI group, RDN and metoprolol significantly decreased the incidence of VAs, and RDN is superior to metoprolol. Compared with metoprolol group, Masson staining showed that RDN significantly reduced the myocardial fibrosis. Both RDN and metoprolol decreased the protein expression of connexin43 (Cx43) compared with MI group, while only RDN lighted this decrease remarkably. Immunohistochemical staining of Tyrosine hydroxylase (TH) and growth associated protein 43 (GAP43) revealed that RDN and metoprolol had similar effect on reducing densities of sympathetic nerve in infarction border zone. According to this study, RDN is more effective in reducing VAs than metoprolol in ischemic cardiomyopathy model.

Chronic obstructive sleep apnea (OSA) may promote the development of atrial fibrillation (AF) by inducing atrial electrical and structural remodeling as well as autonomic nerve hyperinnervation. Here, we investigated the roles of metoprolol in regulation of atrial remodeling induced by chronic OSA. A canine model of chronic OSA was established by stopping the ventilator and closing the airway for 4 h/day every other day for 12 weeks, while metoprolol (5 mg·kg-1·day-1) was continuously administered. Using that model, we observed that increases in sympathetic sprouting and atrial structural remodeling were sharply inhibited by metoprolol. Moreover, metoprolol dramatically inhibited the impairment of atrial energy metabolism by activating the Sirt1-AMPK pathway. In vitro, metoprolol significantly activated the Sirt1-AMPK pathway in intermittent hypoxic and isoproterenol-treated HL-1 cells, and the effect was abolished by the coadministration of EX-527, an inhibitor of Sirt1 activation. In summary, metoprolol protects against chronic OSA-induced atrial remodeling. Our results suggest a new and feasible treatment strategy for AF induced by OSA.

Ventricular arrhythmias are a major source of early mortality in acute myocardial infarction (MI) and remain a major therapeutic challenge. Thus we investigated effects of ivabradine, a presumably specific bradycardic agent versus metoprolol, a β-blocker, at doses offering the same heart rate (HR) reduction, on ventricular arrhythmias in the acute non-reperfused MI in the rat. Immediately after MI induction a single dose of ivabradine/ metoprolol was given. ECG was continuously recorded and ventricular arrhythmias were analyzed. After 6 h epicardial monophasic action potentials (MAPs) were recorded and cardiomyocyte Ca2+ handling was assessed. Both ivabradine and metoprolol reduced HR by 17% and arrhythmic mortality (14% and 19%, respectively, versus 33% in MI, p < 0.05) and ventricular arrhythmias in post-MI rats. Both drugs reduced QTc prolongation and decreased sensitivity of ryanodine receptors in isolated cardiomyocytes, but otherwise had no effect on Ca2+ handling, velocity of conduction or repolarization. We did not find any effects of potential IKr inhibition by ivabradine in this setting. Thus Ivabradine is an equally effective antiarrhythmic agent as metoprolol in early MI in the rat. It could be potentially tested as an alternative antiarrhythmic agent in acute MI when β-blockers are contraindicated.

Renewal of the myocardium by preexisting cardiomyocytes is a powerful strategy for restoring the architecture and function of hearts injured by myocardial infarction. To advance this strategy, we show that combining two clinically approved drugs, but neither alone, muscularizes the heart through cardiomyocyte proliferation. Specifically, in adult murine cardiomyocytes, metoprolol, a cardioselective β1-adrenergic receptor blocker, when given with triiodothyronine (T3, a thyroid hormone) accentuates the ability of T3 to stimulate ERK1/2 phosphorylation and proliferative signaling by inhibiting expression of the nuclear phospho-ERK1/2-specific phosphatase, dual-specificity phosphatase-5. While short-duration metoprolol plus T3 therapy generates new heart muscle in healthy mice, in mice with myocardial infarction-induced left ventricular dysfunction and pathological remodeling, it remuscularizes the heart, restores contractile function and reverses chamber dilatation; outcomes that are enduring. If the beneficial effects of metoprolol plus T3 are replicated in humans, this therapeutic strategy has the potential to definitively address ischemic heart failure.

Myocardial infarction (MI) is the most prevalent cause of cardiovascular death. A possible way of preventing MI maybe by dietary supplements. The present study was thus designed to ascertain the cardio-protective effect of a formulated curcumin and nisin based poly lactic acid nanoparticle (CurNisNp) on isoproterenol (ISO) induced MI in guinea pigs. Animals were pretreated for 7 days as follows; Groups A and B animals were given 0.5 mL/kg of normal saline, group C metoprolol (2 mg/kg), groups D and E CurNisNp 10 and 21 mg/kg respectively (n = 5). MI was induced on the 7th day in groups B-E animals. On the 9th day electrocardiogram (ECG) was recorded, blood samples and tissue biopsies were collected for analyses. Toxicity studies on CurNisNp were carried out. MI induction caused atrial fibrillation which was prevented by pretreatment of metoprolol or CurNisNp. MI induction was also associated with increased expressions of cardiac troponin I (CTnI) and kidney injury molecule-1 (KIM-1) which were significantly reduced in guinea pig's pretreated with metoprolol or CurNisNp (P < 0.05). The LC50 of CurNisNp was 3258.2 μg/mL. This study demonstrated that the formulated curcumin-nisin based nanoparticle confers a significant level of cardio-protection in the guinea pig and is nontoxic.

Clinical trials and studies with ivabradine implicate cardiac pacemaker channels (HCN4) in the pathogenesis of atrial arrhythmias. Because acute changes in cardiac autonomic tone predispose to atrial arrhythmias, we studied humans in whom profound cardiac sympathetic activation was rapidly relieved to test influences of HCN4 inhibition with ivabradine on atrial arrhythmias. We tested 19 healthy participants with ivabradine, metoprolol, or placebo in a double blind, randomized, cross-over fashion on top of selective norepinephrine reuptake inhibition with reboxetine. Subjects underwent combined head up tilt plus lower body negative pressure testing followed by rapid return to the supine position. In the current secondary analysis with predefined endpoints before data unblinding, continuous finger blood pressure and ECG recordings were analyzed by two experienced cardiac electrophysiologists and a physician, blinded for treatment assignment. The total atrial premature activity (referred to as atrial events) at baseline did not differ between treatments. After backwards tilting, atrial events were significantly higher with ivabradine compared with metoprolol or with placebo. Unlike beta-adrenoreceptor blockade, HCN4 inhibition while lowering heart rate does not protect from atrial arrhythmias under conditions of experimental cardiac sympathetic activation. The model in addition to providing insight in the role of HCN4 in human atrial arrhythmogenesis may have utility in gauging potential atrial pro-arrhythmic drug properties.

Phospholamban (PLN) plays a role in cardiomyocyte calcium handling as primary inhibitor of sarco/endoplasmic reticulum Ca2+-ATPase (SERCA). The p.(Arg14del) pathogenic variant in the PLN gene results in a high risk of developing dilated or arrhythmogenic cardiomyopathy with heart failure. There is no established treatment other than standard heart failure therapy or heart transplantation. In this study, we generated a novel mouse model with the PLN-R14del pathogenic variant, performed detailed phenotyping, and tested the efficacy of established heart failure therapies eplerenone or metoprolol. Heterozygous PLN-R14del mice demonstrated increased susceptibility to ex vivo induced arrhythmias, and cardiomyopathy at 18 months of age, which was not accelerated by isoproterenol infusion. Homozygous PLN-R14del mice exhibited an accelerated phenotype including cardiac dilatation, contractile dysfunction, decreased ECG potentials, high susceptibility to ex vivo induced arrhythmias, myocardial fibrosis, PLN protein aggregation, and early mortality. Neither eplerenone nor metoprolol administration improved cardiac function or survival. In conclusion, our novel PLN-R14del mouse model exhibits most features of human disease. Administration of standard heart failure therapy did not rescue the phenotype, underscoring the need for better understanding of the pathophysiology of PLN-R14del-associated cardiomyopathy. This model provides a great opportunity to study the pathophysiology, and to screen for potential therapeutic treatments.

Knowledge about the region-specific absorption profiles from the gastrointestinal tract of orally administered drugs is a critical factor guiding dosage form selection in drug development. We have used a novel approach to study three well-characterized permeability and absorption marker drugs in the intestine. Propranolol and metoprolol (highly permeable compounds) and atenolol (low-moderate permeability compound) were orally co-administered to rats. The site of drug absorption was revealed by high spatial resolution matrix-assisted laser desorption ionization mass spectrometry imaging (MALDI-MSI) and complemented by quantitative measurement of drug concentration in tissue homogenates. MALDI-MSI identified endogenous molecular markers that illustrated the villi structures and confirmed the different absorption sites assigned to histological landmarks for the three drugs. Propranolol and metoprolol showed a rapid absorption and shorter transit distance in contrast to atenolol, which was absorbed more slowly from more distal sites. This study provides novel insights into site specific absorption for each of the compounds along the crypt-villus axis, as well as confirming a proximal-distal absorption gradient along the intestine. The combined analytical approach allowed the quantification and spatial resolution of drug distribution in the intestine and provided experimental evidence for the suggested absorption behaviour of low and highly permeable compounds.

Embryonic stem cell (ESC) derived tissue is a promising tool to be used in different clinical, preclinical and also scientific settings, for example as in vivo biological pacemaker, preclinical drug safety screening tool or ultimately as part of a cell replacement therapy. However, before ESC derived tissue can be used routinely for these purposes in humans, further studies are needed. In this context, the aims of the present study were to examine the effect of antiarrhythmic drugs on human ESC (hESC) und human induced pluripotent stem cell (hiPSC) derived cardiomyocytes by analyzing the beat rate variability (BRV), which can be considered as the in vitro equivalent of the heart rate variability (HRV) in vivo. Short-term recordings of extracellular field potentials of spontaneously beating cardiomyocytes derived from hESCs and hiPSCs were made using Microelectrode Arrays (MEA). The effect of Flecainide, Ivabradine and Metoprolol was tested. The offline analysis of the BRV was mainly focused on time domain methods. Additionally a non-linear analysis method was used. The evaluation of the Poincaré-Plots of the measurements without pharmacological intervention revealed that the vast majority of the scatter plots have a similar, ellipsoid shape. Flecainide and Ivabradine influenced BRV parameters significantly, whereas Metoprolol did not alter the BRV markedly. We detected remarkable similarities between the BRV of hESC and hiPSC derived cardiomyocytes in vitro and the HRV in vivo. The effect of antiarrhythmic drugs on spontaneously beating cardiomyocytes derived from hESC and hiPSC was generally consistent with clinical experiences and also with our previous study based on murine ESC derived cardiomyocytes. In conclusion, our study points out the great potential of hESC and hiPSC derived tissue to be used routinely for many different applications in medicine and science.

Acute Myocardial Infarction (AMI) after Percutaneous Coronary Intervention (PCI) often requires stent implantation leading to cardiovascular injury and cytokine release. Stent implantation induces cytokines production including TNFα, Hs-CRP, IL-1ß, IL2 receptor, IL6, IL8, and IL10, but their co-release is not extensively established. In 311 PCI patients with Drug-Eluting Stent (DES) implantation, we statistically evaluate the correlation of these cytokines release in various clinical conditions, stent numbers, and medications. We observed that TNFα is moderately correlated with IL-1ß (r2 = 0.59, p = 0.001) in diabetic PCI patients. Similarly, in NSTEMI (Non-ST Segment Elevation) patients, TNFα is strongly correlated with both IL-1ß (r2 = 0.97, p = 0.001) and IL8 (r2 = 0.82, p = 0.001). In CAD (Coronary Artery Disease)-diagnosed patients TNFα is highly correlated (r2 = 0.84, p = 0.0001) with IL8 release but not with IL-1ß. In patients with an increased number of stents, Hs-CRP is significantly coupled with IL8 > 5 pg/ml (t-statistic = 4.5, p < 0.0001). Inflammatory suppressor drugs are correlated as TNFα and IL8 are better suppressed by Metoprolol 23.75 (r2 = 0.58, p < 0.0001) than by Metoprolol 11.87 (r2 = 0.80, p = 0.5306). Increased TNFα and IL-1ß are better suppressed by the antiplatelet drug Brilinta (r2 = 0.30, p < 0.0001) but not with Clopidogrel (r2 = 0.87, p < 0.0001). ACI/ARB Valsartan 80 (r2 = 0.43, p = 0.0011) should be preferred over Benazepril 5.0 (r2 = 0.9291, p < 0.0001) or Olmesartan (r2 = 0.90, p = 0.0001). Thus, the co-release of IL-1ß, IL8 with TNFα, or only IL8 with TNFα could be a better predictor for the outcome of stent implantation in NSTEMI and CAD-diagnosed AMI patients respectively. Cytokine suppressive medications should be chosen carefully to inhibit further cardiovascular damage.

14-O-[(4,6-Diaminopyrimidine-2-yl)thioacetyl] mutilin (DPTM) is a promising drug candidate with excellent antibacterial activity against Gram-positive bacteria. The present study was designed to characterize its Cytochrome P450 (CYP) enzymes inhibition activities and the genotoxicity with the standard Ames test. We determined the inhibitory effects of DPTM on CYP1A2, CYP2D1/6, CYP2E1, CYP2C11/9 and CYP3A/4 in rat liver microsomes (RLMs) and in human liver microsomes (HLMs). The mRNA expressions of the above CYP isoforms and their transcriptional regulators were also evaluated using the Hep G2 cell model. The results showed DPTM exhibited a moderate inhibitory potential against CYP3A/4 (IC50 values of 10 ± 2 and 8 ± 2 μM, respectively) and weak against the other CYP enzymes based on their IC50 values. Compared to the control, CYP isoforms and their transcriptional regulators mRNA expressions significantly increased when the Hep G2 cells were treated with DPTM for a certain period of time. In the Ames test, Salmonella strains TA97, TA98, TA100, TA102 and TA1535 were treated with or without the metabolic activation (S9). Analysis showed the average number of revertant colonies per plate was less in double in the groups treated with DPTM than that in the negative control plate and showed no dose-related increase.

Patients with heart failure (HF) have high mortality and mobility. Xinmailong (XML) injection, a Chinese Medicine, is clinically effective in treating HF. However, the mechanism of XML's effectiveness on HF was unclear, and thus, was the target of the present study. We created a mouse model of pressure-overload-induced HF with transverse aortic constriction (TAC) surgery and compared among 4 study groups: SHAM (n = 10), TAC (n = 12), MET (metoprolol, positive drug treatment, n = 7) and XML (XML treatment, n = 14). Dynamic changes in cardiac structure and function were evaluated with echocardiography in vivo. In addition, H9C2 rat cardiomyocytes were cultured in vitro and the phosphorylation of ERK1/2, AKT, GSK3β and protein expression of GATA4 in nucleus were detected with Western blot experiment. The results showed that XML reduced diastolic thickness of left ventricular posterior wall, increased ejection fraction and fraction shortening, so as to inhibit HF at 2 weeks after TAC. Moreover, XML inhibited the phosphorylation of ERK1/2, AKT and GSK3β, subsequently inhibiting protein expression of GATA4 in nucleus (P < 0.001). Together, our data demonstrated that XML inhibited the TAC-induced HF via inactivating the ERK1/2, AKT/GSK3β, and GATA4 signaling pathway.

In cardiovascular research, several mouse strains with differing genetic backgrounds are used to investigate mechanisms leading to and sustaining ventricular arrhythmias. The genetic background has been shown to affect the studied phenotype in other research fields. Surprisingly little is known about potential strain-specific susceptibilities towards ventricular arrhythmias in vivo. Here, we hypothesized that inter-strain differences reported in the responsiveness of the β-adrenergic pathway, which is relevant for the development of arrhythmias, translate into a strain-specific vulnerability. To test this hypothesis, we characterized responses to β-adrenergic blockade (metoprolol) and β-adrenergic stimulation (isoproterenol) in 4 mouse strains commonly employed in cardiovascular research (Balb/c, BS, C57Bl/6 and FVB) using telemetric ECG recordings. We report pronounced differences in the electrical vulnerability following isoproterenol: Balb/c mice developed the highest number and the most complex arrhythmias while BS mice were protected. Balb/c mice, therefore, seem to be the background of choice for experiments requiring the occurrence of arrhythmias while BS mice may give insight into electrical stability. Arrhythmias did not correlate with the basal β-adrenergic tone, with the response to β-adrenergic stimulation or with the absolute heart rates during β-adrenergic stimulation. Thus, genetic factors dominate the susceptibility to ventricular arrhythmias in this model of β-adrenergic stimulation.

Detection of antihypertensive drugs in biological samples is an important tool to assess the adherence of hypertensive patients. Urine and serum/plasma screenings based on qualitative results may lead to misinterpretations regarding drugs with a prolonged detectability. The aim of the present study was to develop a method that can be used for therapeutic drug monitoring (TDM) of antihypertensive drugs with focus on adherence assessment. Therefore, a method for quantification of four diuretics and four β-blockers using high-performance liquid chromatography-mass spectrometric analysis (LC-MS/MS) of combined acidic and basic serum extracts was developed and validated. The method was applied to 40 serum samples from 20 patients in a supervised medication setting (trough and peak serum samples). Literature data on therapeutic concentration ranges, as well as dose-related drug concentrations (calculated from data of pharmacokinetic studies) were used to evaluate adherence assessment criteria. Concentrations were measured for bisoprolol (n = 9 patients), metoprolol (n = 7), nebivolol (n = 1), canrenone (n = 2, metabolite of spironolactone), hydrochlorothiazide (n = 10) and torasemide (n = 8). The measured concentrations were within the therapeutic reference ranges, except for 24% of the samples (mainly β-blockers). In contrast, all measured concentrations were above the lower dose-related concentration (DRC), which appears superior in evaluating adherence. In conclusion, the quantitative analysis of antihypertensive drugs in serum samples and its evaluation on the basis of the individually calculated lower DRC is a promising tool to differentially assess adherence. This method could possibly detect a lack of adherence or other causes of insufficient therapy more reliably than qualitative methods.

Chlorthalidone (CTD) is more potent than hydrochlorothiazide (HCTZ) in reducing blood pressure (BP) in hypertensive patients, though both are plagued with BP response variability. However, there is a void in the literature regarding the genetic determinants contributing to the variability observed in BP response to CTD. We performed a discovery genome wide association analysis of BP response post CTD treatment in African Americans (AA) and European Americans (EA) from the Pharmacogenomic Evaluation of Antihypertensive Responses-2 (PEAR-2) study and replication in an independent cohort of AA and EA treated with HCTZ from the PEAR study, followed by a race specific meta-analysis of the two studies. Successfully replicated SNPs were further validated in beta-blocker treated participants from PEAR-2 and PEAR for opposite direction of association. The replicated and validated signals were further evaluated by protein-protein interaction network analysis. An intronic SNP rs79237970 in the WDR92 (eQTL for PPP3R1) was significantly associated with better DBP response to CTD (p = 5.76 × 10-6, β = -15.75) in the AA cohort. This SNP further replicated in PEAR (p = 0.00046, β = -9.815) with a genome wide significant meta-analysis p-value of 8.49 × 10-9. This variant was further validated for opposite association in two β-blockers treated cohorts from PEAR-2 metoprolol (p = 9.9 × 10-3, β = 7.47) and PEAR atenolol (p = 0.04, β = 4.36) for association with DBP. Studies have implicated WDR92 in coronary artery damage. PPP3R1 is the regulatory subunit of the calcineurin complex. Use of calcineurin inhibitors is associated with HTN. Studies have also shown polymorphisms in PPP3R1 to be associated with ventricular hypertrophy in AA hypertensive patients. Protein-protein interaction analysis further identified important hypertension related pathways such as inositol phosphate-mediated signaling and calcineurin-NFAT signaling cascade as important biological process associated with PPP3R1 which further strengthen the potential importance of this signal. These data collectively suggest that WDR92 and PPP3R1 are novel candidates that may help explain the genetic underpinnings of BP response of thiazide and thiazide-like diuretics and help identify the patients better suited for thiazide and thiazide-like diuretics compared to β-blockers for improved BP management. This may further help advance personalized approaches to antihypertensive therapy.

Diabetic retinopathy (DR) is the most frequent microvascular complication of diabetes mellitus, however, its underlying biological mechanisms remain poorly understood. We examined single nucleotide polymorphisms linked to 486 blood metabolites through extensive genome-wide association studies conducted on individuals of European ancestry. The FinnGen Biobank database served as a reference to define DR. Two-sample MR analysis was conducted to reveal the association between the levels of genetically predicted circulating metabolites and the susceptibility to DR. To validate the robustness of the obtained findings, sensitivity analyses with weighted median, weighted mode, and MR-Egger were conducted. 1-oleoylglycerophosphoethanolamine (odds ratio [OR] (OR per one standard deviation [SD] increase) = 0.414; 95% confidence interval [CI] 0.292-0.587; P = 7.613E-07, PFDR = 6.849E-06), pyroglutamine (OR per one SD increase = 0.414; 95% confidence interval [CI] 0.292-0.587; P = 8.31E-04, PFDR = 0.007), phenyllactate (PLA) (OR per one SD increase = 0.591; 95% confidence interval [CI] 0.418-0.836; P = 0.003, PFDR = 0.026), metoprolol acid metabolite (OR per one SD increase = 0.978; 95% confidence interval [CI] 0.962-0.993; P = 0.005, PFDR = 0.042), 10-undecenoate (OR per one SD increase = 0.788; 95% confidence interval [CI] 0.667-0.932; P = 0.005, PFDR = 0.049), erythritol (OR per one SD increase = 0.691; 95% confidence interval [CI] 0.513-0.932; P = 0.015, PFDR = 0.034), 1-stearoylglycerophosphoethanolamine (OR per one SD increase = 0.636; 95% confidence interval [CI] 0.431-0.937; P = 0.022, PFDR = 0.099), 1-arachidonoylglycerophosphoethanolamine (OR per one SD increase = 0.636; 95% confidence interval [CI] 0.431-0.937; P = 0.030, PFDR = 0.099) showed a significant causal relationship with DR and could have protective effects. stachydrine (OR per one SD increase = 1.146; 95% confidence interval [CI] 1.066-1.233; P = 2.270E-04, PFDR = 0.002), butyrylcarnitine (OR per one SD increase = 1.117; 95% confidence interval [CI] 1.023-1.219; P = 0.014, PFDR = 0.062), 5-oxoproline (OR per one SD increase = 1.569; 95% confidence interval [CI] 1.056-2.335; P = 0.026, PFDR = 0.082), and kynurenine (OR = 1.623; 95% CI 1.042-2.526; P = 0.041, PFDR = 0.097) were significantly associated with an increased risk of DR. This study identified metabolites have the potential to be considered prospective compounds for investigating the underlying mechanisms of DR and for selecting appropriate drug targets.