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A total of 195 patients with moderate to severe HF (NYHA Functional Class III to IV) were selected and randomized into two groups: an observation group and a BNP group. The groups were established to observe the clinical conditions and establish plasma BNP levels to guide the application of metoprolol succinate. The average start-up of metoprolol succinate and average dose of metoprolol succinate after one month, as well as the recurrence rate and mortality of HF during hospital stay were compared between the two groups.
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The effects of beta-blockers on acute myocardial infarction can be divided into those that are immediate and long-term (secondary prevention). beta-blockers given early in the course of infarction may diminish myocardial oxygen demand and therefore reduce chest pain and infarct size. Many clinical trials have clearly shown that both early and long-term treatment with beta-blockers reduce cardiac mortality and the rate of re-infarction. As seen in recommendations of ACC (American College of Cardiology)/AHA (American Heart Association) guidelines for management of acute myocardial infarction, all patients without a contraindication to beta-blockers should be treated with beta-blockers from very early course of the onset and be continued indefinitely.
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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.
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The antiarrhythmic effect of metoprolol after chronic treatment has been evaluated by 24 hour Holter monitoring in 16 patients with several premature ventricular beats and in 14 patients with chronic atrial fibrillation and compared with the effect of a placebo. Metoprolol induced a mean decrease of heart rate of 14.5% in the 16 patients and reduced the mean value/min of the ventricular premature beats of the 51.2%. In addition the use of metoprolol abolished the ventricular premature beats in 9 cases, while in two cases there was an increase of their frequency. In the 14 patients with chronic atrial fibrillation metoprolol was able to reverse to sinus rhythm three of the patients and in the remaining 11 decreased the ventricular heart rate of the 33%.
We have characterized a phosphatidic acid phosphatase (PAP, EC 126.96.36.199) that is associated with cell membranes from rat brain using [32P]phosphatidic acid as substrate in a simple assay. The enzyme could be activated by Triton X-100, cholic acid and Chaps and inhibited by Lubrol PX and sodium dodecyl sulfate. The optimal pH was between 6.0 and 7.0 Mg2+ was not essential for enzyme activity. The enzyme activity was decreased by about 50% by Ca2+ at concentrations of 0.1 to 1 mmol/l. Zn2+ inhibited the enzyme by 50% at concentrations of about 10 mumol/l in the absence of, and 100 nmol/l in the presence (3 mmol/l) of, Triton X-100. NaF decreased the activity by about 50% at concentrations between 0.3 and 1 mmol/l when Triton X-100 was added, but did not inhibit the enzyme if the detergent was not present. N-Ethylmaleimide (NEM) did not affect the enzyme. In the absence of Triton X-100, propranolol and metoprolol enhanced the PAP activity. In the presence of 3 mmol/l Triton X-100, the enzyme was inhibited by about 50% by propranolol at a concentration of 10 mmol/l, whereas metoprolol caused only a slight inhibition of PAP. The Km for phosphatidic acid was 150 mumol/l and was changed to 20 mumol/l by 3 mmol/l Triton X-100 without the Vmax being changed. Enzyme activity could be solubilized by 1-5% (w/v) Triton X-100. Gel filtration chromatography showed a M(r) of 320,000. This membrane-associated PAP from neuronal tissue probably belongs among the NEM-insensitive forms of PAP enzymes which have been proposed to play a role in transmembrane signal transduction via phospholipase D.
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Utilization of chemical penetration enhancers in conjunction with iontophoresis is regarded as the most effective method to enhance the passage of molecules across the skin barrier. A systematic approach to enhance the transdermal delivery of metoprolol tartrate and the subsequent release of the drug depot in the skin was investigated. Gel formulations with proximate viscosity were prepared and assessed for the effect of polymers (carbopol, hydroxypropyl methyl cellulose, and methyl cellulose), permeation enhancers (5% w/w, sodium lauryl sulfate (SLS), dimethyl formamide, n-methyl-2-pyrrolidone, and polyethylene glycol 400), and the combination approach (permeation enhancers with iontophoresis-0.5 mA/cm² on the drug delivery. The flux values observed in passive (4.59-5.89 µg/cm²/h) and iontophoresis (37.99-41.57 µg/cm²/h) processes revealed that the permeation of metoprolol was not influenced by the polymers studied, under similar conditions, and further studies were carried out using carbopol gel as a representative polymer. Appreciable enhancement (~5-fold) in drug delivery was observed with SLS in the passive process while the optimum iontophoretic delivery condition ensured better delivery (~7-fold). Combination of iontophoresis with SLS further enhanced the drug delivery (~9-fold) and leads to noticeable drug retention in the skin as well. Moreover, the drug retained in the cutaneous layer of the skin eventually released over a period of time (5 days) and followed a near first order profile. This study concludes that the combination of iontophoresis with SLS augmented the metoprolol delivery and rendered skin drug depot, which eventually released over a period of time.
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Two single-dose, replicated, crossover studies were first conducted in healthy volunteers (N=20 each) to compare the effect of 5 Gm of sorbitol and sucrose on bioequivalence of 150 mg ranitidine or 50 mg metoprolol in aqueous solution, followed by a single-dose, nonreplicated, crossover study (N=24) to determine the threshold of sorbitol effect on bioequivalence of 150 mg ranitidine in solution.
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We evaluated acute hemodynamic effects of metoprolol +/- nitroglycerin in 11 patients with left ventricular dysfunction and biopsy-proven lymphocytic myocarditis. Acute administration of metoprolol improved ejection phase indexes, probably through the prolongation of diastole; the addition of a vasodilator further enhanced these effects by improving arterial elastance.
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A single causative mechanism for development of hypoglycemia unawareness in insulin-dependent diabetes mellitus (IDDM) is not yet apparent. Reduced adrenergic sensitivity may be part of the explanation. This study was carried out to investigate the effect of hypoglycemia on beta-adrenergic sensitivity. Ten healthy male subjects (age 19-23 years) gave informed consent to take part in the study. They were hospitalized overnight at the University Hospital of Tromsø, Department of Clinical Research, on two occasions. Isoprenaline and metoprolol sensitivity tests were performed the morning after hospitalization: once after an intravenous (iv) injection of placebo (0.9% NaCl), and once after an iv injection of insulin (0.15 IU insulin/kg body weight) to induce hypoglycemia. The dose of isoprenaline needed to increase heart rate (HR) by 25 beats per minute (bpm) (I25), and the dose of metoprolol (M-12.5) needed to inhibit I25 with 50% or 12.5 bpm, when injected simultaneously, were used as determinants of isoprenaline and metoprolol sensitivity. In this study, there was a significant (p < 0.05) increase both in I25 and M-12.5 after hypoglycemia. The dose-response curve of isoprenaline/HR was significantly shifted to the right after hypoglycemia. This study shows that acute hypoglycemia induces a reduction in beta-adrenergic sensitivity, and it supports the hypothesis of reduced beta-adrenergic sensitivity as an important pathophysiological mechanism in hypoglycemia unawareness in IDDM.
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The effects of diazepam on the pharmacokinetics and pharmacodynamics of two lipophilic beta-adrenoceptor antagonists (propranolol and metoprolol) and a hydrophilic beta-adrenoceptor antagonist (atenolol) were compared in 12 subjects. Administration of propranolol and metoprolol produced small increases in the AUC0-8h for diazepam compared with placebo (P less than 0.05 for metoprolol). Atenolol had no significant effect on the AUC0-8h for diazepam. The increase in the AUC0-8h was accompanied by increases in the plasma concentrations of N-desmethyldiazepam. Diazepam had no significant effect on the pharmacokinetics of either propranolol or atenolol. The pharmacokinetic interaction could be attributed to inhibition of diazepam metabolism by the lipophilic beta-adrenoceptor antagonists. The pharmacodynamic studies showed that when compared with placebo or atenolol there was a significant impairment of kinetic visual acuity (KVA) when diazepam was co-administered with metoprolol. Although there was a significant correlation (P less than 0.02) between plasma concentrations of diazepam and impairment of KVA, the pharmacodynamic interactions may not be due solely to the small pharmacokinetic interaction observed.
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The aim of this study was to assess the effectiveness and safety of different strategies of ivabradine therapy by comparing the effects on heart rate (HR), blood pressure (BP), and image quality of coronary CT angiography (CTA).
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Myocardial infarction (MI) was induced in male rats by ligation of the left coronary artery. Three different groups of rats were studied, MI rats treated with metoprolol (n=17), MI rats treated with saline (n=14) and sham-operated rats (n=12). The treatment with metoprolol 1 mg/kg/h was initiated in the third week post-infarct for a period of 6 weeks. All rats were investigated non-invasively with volume-selective 31P magnetic resonance spectroscopy and echocardiography for evaluation of left ventricular (LV) energy metabolism, morphology and function. Plasma concentration of IL-1beta and IL-6 and density of beta-adrenergic receptors were analyzed.
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To evaluate the efficacy, tolerability, and blood pressure (BP) lowering effect of extended release metoprolol succinate (ER metoprolol) in children 6 to 16 years of age with established hypertension.
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The blood pressure and pulse interval in adult Wistar-Kyoto (WKY) rats were recorded on a beat-to-beat basis for two consecutive 30 min periods. During one of these periods the BRS was determined pharmacologically by injections of nitroprusside and phenylephrine. Measurements were performed after administration of saline as vehicle or during manipulation of the autonomic nervous system by infusion of metoprolol, methyl-atropine and hexamethonium. Sequential time-series methods for continuous BRS calculation were tested for 24 h periods in intact WKY rats as well as in WKY rats that had been subjected to sino-aortic denervation or to electrical lesioning of the nucleus tractus solitarius.
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Determining the mechanism of sorafenib-mediated cardiotoxicity.
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These results demonstrate that the inhibition of rat myometrial contractions with CL 316243 is mediated by β(3)-adrenoceptor subtype and increased cAMP and cGMP levels.
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Typical CYP2D6 substrates generally contain a basic nitrogen atom that interacts with Asp(301) and/or Glu(216) and an aromatic moiety adjacent to the site of metabolism. Recently, we found novel acidic substrates for CYP2D6, pactimibe, and its indole metabolite, R-125528, that are not protonated but are negatively charged at physiological pH. The K(m) value of R-125528 in CYP2D6-expressing microsomes was determined to be 1.74 microM, which was comparable with those of typical basic CYP2D6 substrates (1-10 microM). Pactimibe has lower affinity than R-125528; however, the K(m) value was comparable with that of metoprolol. Interestingly, their sites of metabolism, the omega-1 position of the N-octyl indoline/indole group, were relatively distant from the aromatic moiety. A pactimibe analog with an N-decyl chain was similarly labile against CYP2D6; however, analogs with N-hexyl or N-dodecyl chains were stable to CYP2D6. An induced fit docking of the ligands with an X-ray crystal structure of substrate-free CYP2D6 (Protein Data Bank code 2F9Q) indicated the involvement of an electrostatic interaction between the carboxyl group and Arg(221) and hydrophobic interaction between the aromatic moiety and Phe(483). The docking model correctly positioned the site of metabolism above the heme. The effect of the N-alkyl chain length of pactimibe analogs on their CYP2D6 metabolic stability was plausibly explained by the docking model. In conclusion, we report herein a novel CYP2D6 binding mode for the acidic substrates pactimibe and R-125528. Further investigation, such as a site-directed mutation, will be necessary to directly demonstrate the involvement of Arg(221) in CYP2D6 binding.
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The objective of this study was to evaluate the suitability and acceptance criteria of isolated rat jejunum model for Biopharmaceutics Classification System (BCS)-permeability classification. The evaluation followed recommended procedures including investigation of tissue integrity by applying damage triggers (nitrogen gassing, elevated temperature, azide addition), characterization of transporter functionality, and expression and development of correlation between rats' apparent permeability coefficient (P(app) ) versus humans' and versus oral fraction absorbed (f(a) ) in humans. Firstly, damage triggers caused a decrease in transepithelial resistance and potential difference and increase in lucifer yellow (LY) and fluorescein isothiocyanate (FITC)-dextran P(app) . However, only FITC-dextran P(app) 's increase was considered significant in all treatment groups, making FITC-dextran a better indicator of jejunum integrity than LY. Secondly, the expression level of selected intestinal transporters highly correlated between rat and human and functionality of P-glycoprotein was confirmed. P(app) of investigated drugs correlated with human f(a) (R(2) = 0.85, n = 20) and with human permeability coefficients (R(2) = 0.86, n = 13). Utility of described model for BCS classification was shown on levetiracetam, where significantly higher permeability of levetiracetam as compared with internal standard metoprolol was determined (t-test, p = 0.005). In conclusion, isolated rat jejunum model is a useful tool not only for mechanistic investigation, but also for permeability classification according to BCS and consequently for BCS-based biowaiver procedures.
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Single-photon emission CT of the heart was used to observe coronary blood flow and reveal the maximum perfusion region in patients with coronary heart disease (CHD) treated with beta-adrenoblockers and calcium channel blockers. Dynamic observation showed changes and redistribution of myocardial perfusion. Specific features of coronary blood flow were demonstrated depending on the therapeutic modality (beta-blocker metoprolol, calcium channel blocker amlodipine). Parameters of prognostic value were identified depending on the effectiveness of the agents used. This approach together with the traditional nosological one to the choice of CHD therapy permits to individualize the therapeutic influence depending on myocardial micriocirculatory features, such as the spread and depth of perfusion disturbances.
When stratified according to treatment and presence of obesity (body mass index < or = 27 kg/m2), the mean (SD) fall in blood pressure in the beta blocker group was 24 (13)/18 (10) mm Hg in obese patients and 18 (19)/12 (13) mm Hg in lean patients. In the calcium entry blocker group, the fall in blood pressure was 21 (15)/17 (6) mm Hg in lean patients and 18 (11)/8 (10) mm Hg in obese patients. After taking age and blood pressure before treatment into account there was a significant interaction between obesity and drug therapy (p = 0.019) with a better diastolic blood pressure response to calcium entry blockers in lean patients and to beta blockers in obese hypertensive patients.
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In the original trial, all patients received 162 mg of aspirin plus 75 mg of clopidogrel daily or matching placebo and metoprolol (15 mg intravenous then 200 mg oral daily) or matching placebo. All other aspects of patients' treatments were at the discretion of responsible doctors.
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We included 60 patients (mean age 71 ± 9 years, 18 women) with permanent AF and normal left ventricular function in a randomized, cross-over, investigator-blind study. Diltiazem 360 mg, verapamil 240 mg, metoprolol 100 mg, and carvedilol 25 mg were administered o.d. for 3 weeks. At baseline and on the last day of each treatment period, the patients underwent a maximal cardiopulmonary exercise test and blood samples were obtained at rest and at peak exercise. The exercise capacity (peak VO2) was significantly lower during treatment with metoprolol and carvedilol compared with baseline (no treatment) or treatment with diltiazem and verapamil (P < 0.001 for all). Compared with baseline, treatment with diltiazem and verapamil significantly reduced the NT-proBNP levels both at rest and at peak exercise, whereas treatment with metoprolol and carvedilol increased the levels (P < 0.05 for all).
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The HF pharmacogenetic literature is still in its very early stages, but there are promising candidate genetic variants that may identify which HF patients are most likely to benefit from beta-blockers and ACE inhibitors and patients that may require additional therapies.
Ghrelin is an acylated peptide hormone mainly secreted from the stomach. When administrated externally it modulates vascular tone mainly through the regulation of autonomic nerve activity. However, the effects of blood pressure (BP) on the production and secretion of ghrelin remain to be clarified.
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The recovery of the ECG signs of anterior myocardial infarction has been studied in 70 patients. A significant increase in R-wave amplitude and decrease in Q-wave amplitude on 24-lead precordial mapping was observed during one year after infarction. Patients with lower initial heart rate showed a greater recovery of R- and Q-wave amplitudes, as did patients with smaller infarcts, as assessed by peak heat-stable lactate dehydrogenase (LDH).
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To study the correlation between the absorption rate constants of beta-adrenoreceptor antagonists in rat small intestinal segments and their molecular structural parameters.
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The study aimed to report our experience of intravenous flecainide administration in the treatment of paroxysmal atrial fibrillation (PAF) in the Emergency Room (ER).