- Cardiac K2P13.1 (THIK-1) two-pore-domain K+ channels: Pharmacological regulation and remodeling in atrial fibrillation. [Journal Article]
- PBProg Biophys Mol Biol 2019; 144:128-138
- Cardiac two-pore-domain potassium (K2P) channels have been proposed as novel antiarrhythmic targets. K2P13.1 (THIK-1) channels are expressed in the human heart, and atrial K2P13.1 levels are reduced …
Cardiac two-pore-domain potassium (K2P) channels have been proposed as novel antiarrhythmic targets. K2P13.1 (THIK-1) channels are expressed in the human heart, and atrial K2P13.1 levels are reduced in patients with atrial fibrillation (AF) or heart failure. The first objective of this study was to investigate acute effects of antiarrhythmic drugs on human K2P13.1 currents. Second, we assessed atrial K2P13.1 remodeling in AF pigs to validate the porcine model for future translational evaluation of K2P13.1-based antiarrhythmic concepts. K2P13.1 protein expression was studied in domestic pigs during AF induced by atrial burst pacing. AF was associated with 66% reduction of K2P13.1 levels in the right atrium at 21-day follow-up. Voltage clamp electrophysiology was employed to elucidate human K2P13.1 channel pharmacology in Xenopus oocytes. Propafenone (-26%; 100 μM), mexiletine (-75%; 1.5 mM), propranolol (-38%; 200 μM), and lidocaine (-59%; 100 μM) significantly inhibited K2P13.1 currents. By contrast, K2P13.1 channels were not markedly affected by quinidine, carvedilol, metoprolol, amiodarone and verapamil. Concentration-dependent K2P13.1 blockade by mexiletine occurred rapidly with membrane depolarization and was frequency-independent. Mexiletine reduced K2P13.1 open rectification properties and shifted current-voltage relationships towards more negative potentials. In conclusion, atrial expression and AF-associated downregulation of K2P13.1 channels in a porcine model resemble human findings and support a general role for K2P13.1 in AF pathophysiology. K2P13.1 current sensitivity to antiarrhythmic drugs provides a starting point for further development of an emerging antiarrhythmic paradigm.
- Treatment with verapamil for restoration of sinus rhythm in atrial fibrillation with rapid ventricular response: A case report. [Journal Article]
- MMedicine (Baltimore) 2019; 98(23):e15892
- CONCLUSIONS: For the treatment of AF, nondihydropyridine calcium antagonists can be tried in the absence of antiarrhythmic drugs.
- Propafenone-associated Gross Hematuria: A Case Report and Review of the Literature. [Journal Article]
- CTClin Ther 2019 Jun 01
- CONCLUSIONS: A probable association exists between gross hematuria and propafenone.
- Identification of the A293 (AVE1231) Binding Site in the Cardiac Two-Pore-Domain Potassium Channel TASK-1: a Common Low Affinity Antiarrhythmic Drug Binding Site. [Journal Article]
- CPCell Physiol Biochem 2019; 52(5):1223-1235
- CONCLUSIONS: We have identified the A293 binding site in the central cavity of TASK-1 and propose that this site might represent a conserved site of action for many low affinity antiarrhythmic TASK-1 blockers.
- "Pill-in-the-Pocket" Treatment of Propafenone Unmasks ECG Brugada Pattern in an Atrial Fibrillation Patient With a Common SCN5A R1193Q Polymorphism. [Journal Article]
- FPFront Physiol 2019; 10:353
- CONCLUSIONS: A common SCN5A polymorphism R1193Q enhances UDB by propafenone and predisposes the patients to drug-induced BrS with PIP treatment. Our data suggest that R1193Q polymorphism is likely to be a genetic marker for the major adverse effects associated with propafenone PIP approach for AF patients' management. Ajmaline challenge to rule out the presence of BrS should be considered prior to propafenone PIP therapy in AF patients who are identified to have R1193Q polymorphism.
- [Transcriptomics study on mechanism of Aconiti Lateralis Radix Praeparata in treatment of rats with acute heart failure]. [Journal Article]
- ZZZhongguo Zhong Yao Za Zhi 2019; 44(1):131-140
- In this study,transcriptomics technique was used to investigate the mechanism of action of Aconiti Lateralis Radix Praeparata on acute heart failure rats induced by propafenone hydrochloride.First,ra…
In this study,transcriptomics technique was used to investigate the mechanism of action of Aconiti Lateralis Radix Praeparata on acute heart failure rats induced by propafenone hydrochloride.First,rats were randomly divided into normal group,model group and administration group(1.25,2.5,5 g·kg-1).A rat with acute heart failure was constructed by intravenous femoral administration of proparone hydrochloride.The changes of heart rate,+dp/dtmaxand-dp/dtmaxat 5,10,20,30 and 60 min were recorded.Then another group of rats were given the same drug delivery method.In another group of animals,serum TNF-α could be determined by ELISA with the same dosage method.High-throughput sequencing technology was used to detect all gene expression differences in cardiac tissue samples of rats with acute heart failure.Through functional annotation and enrichment analysis,gene expression signaling pathways of rats with acute heart failure and rats with post-administration heart failure were screened out.The results showed that heart rate and LV+dp/dtmaxand LV-dp/dtmaxwere significantly decreased in the model group(P<0.05),while heart rate and LV+dp/dtmax and LV-dp/dtmaxwere significantly increased in the drug group(P<0.05,P<0.01).Moreover,ANP,BNP and TNF-α in acute heart failure rats was significantly decreased in high-dose aconite decoction group(P<0.05).Transcriptomics analysis showed that the mechanism of action was mainly related to activation of PI3 K-AKT signaling pathway and Jak-STAT pathway.Compared with the model group,aconite decoction up-regulated the expression of phosphatidylinostol 3-kinase(PI3 K),lysophosphatidic acid(LAP3),Bcl-3 and STAT genes,and down-regulated the expression of integrin(ITGA),nuclear orphan receptor(Nur77) genes.It could be concluded that the mechanism of aconite in treating acute heart failure rats may be related to the regulation of the PI3 k-Akt/Jak-STAT pathway.
- A 35-year effective treatment of catecholaminergic polymorphic ventricular tachycardia with propafenone. [Case Reports]
- HCHeartRhythm Case Rep 2019; 5(2):74-77
- In silico Assessment of Pharmacotherapy for Human Atrial Patho-Electrophysiology Associated With hERG-Linked Short QT Syndrome. [Journal Article]
- FPFront Physiol 2018; 9:1888
- Short QT syndrome variant 1 (SQT1) arises due to gain-of-function mutations to the human Ether-à-go-go-Related Gene (hERG), which encodes the α subunit of channels carrying rapid delayed rectifier po…
Short QT syndrome variant 1 (SQT1) arises due to gain-of-function mutations to the human Ether-à-go-go-Related Gene (hERG), which encodes the α subunit of channels carrying rapid delayed rectifier potassium current, IKr. In addition to QT interval shortening and ventricular arrhythmias, SQT1 is associated with increased risk of atrial fibrillation (AF), which is often the only clinical presentation. However, the underlying basis of AF and its pharmacological treatment remain incompletely understood in the context of SQT1. In this study, computational modeling was used to investigate mechanisms of human atrial arrhythmogenesis consequent to a SQT1 mutation, as well as pharmacotherapeutic effects of selected class I drugs-disopyramide, quinidine, and propafenone. A Markov chain formulation describing wild type (WT) and N588K-hERG mutant IKr was incorporated into a contemporary human atrial action potential (AP) model, which was integrated into one-dimensional (1D) tissue strands, idealized 2D sheets, and a 3D heterogeneous, anatomical human atria model. Multi-channel pharmacological effects of disopyramide, quinidine, and propafenone, including binding kinetics for IKr/hERG and sodium current, INa, were considered. Heterozygous and homozygous formulations of the N588K-hERG mutation shortened the AP duration (APD) by 53 and 86 ms, respectively, which abbreviated the effective refractory period (ERP) and excitation wavelength in tissue, increasing the lifespan and dominant frequency (DF) of scroll waves in the 3D anatomical human atria. At the concentrations tested in this study, quinidine most effectively prolonged the APD and ERP in the setting of SQT1, followed by disopyramide and propafenone. In 2D simulations, disopyramide and quinidine promoted re-entry termination by increasing the re-entry wavelength, whereas propafenone induced secondary waves which destabilized the re-entrant circuit. In 3D simulations, the DF of re-entry was reduced in a dose-dependent manner for disopyramide and quinidine, and propafenone to a lesser extent. All of the anti-arrhythmic agents promoted pharmacological conversion, most frequently terminating re-entry in the order quinidine > propafenone = disopyramide. Our findings provide further insight into mechanisms of SQT1-related AF and a rational basis for the pursuit of combined IKr and INa block based pharmacological strategies in the treatment of SQT1-linked AF.
- Pharmacogenetics of myotonic hNav1.4 sodium channel variants situated near the fast inactivation gate. [Journal Article]
- PRPharmacol Res 2019; 141:224-235
- Sodium channel myotonia and paramyotonia congenita are caused by gain-of-function mutations in the skeletal muscle voltage-gated sodium channel hNav1.4. The first-line drug is the sodium channel bloc…
Sodium channel myotonia and paramyotonia congenita are caused by gain-of-function mutations in the skeletal muscle voltage-gated sodium channel hNav1.4. The first-line drug is the sodium channel blocker mexiletine; however, some patients show side effects or limited responses. We previously showed that two hNav1.4 mutations, p.G1306E and p.P1158L, reduce mexiletine potency in vitro, whereas another sodium channel blocker, flecainide, is less sensitive to mutation-induced gating defects. This observation was successfully translated to p.G1306E and p.P1158L carriers. Thus, the aim of this study was to perform a pharmacological characterization of myotonic Nav1.4 mutations clustered near the fast inactivation gate of the channel. We chose seven mutations (p.V1293I, p.N1297S, p.N1297K, p.F1298C, p.G1306E, p.I1310N, and p.T1313M) from the database of Italian and French networks for muscle channelopathies. Recombinant hNav1.4 mutants were expressed in HEK293T cells for functional and pharmacological characterization using the patch-clamp technique. All the studied mutations impair the kinetics and/or voltage dependence of fast inactivation, which is likely the main mechanism responsible for myotonia. The severity of myotonia is well-correlated to the enhancement of window currents generated by the intersection of the activation and fast inactivation voltage dependence. Five of the six mutants displaying a significant positive shift of fast inactivation voltage dependence reduced mexiletine inhibition in an experimental condition mimicking myotonia. In contrast, none of the mutations impairs flecainide block nor does p.T1313M impair propafenone block, indicating that class Ic antiarrhythmics may constitute a valuable alternative. Our study suggests that mutation-driven therapy would be beneficial to myotonic patients, greatly improving their quality of life.
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- Regioselective hydroxylation of an antiarrhythmic drug, propafenone, mediated by rat liver cytochrome P450 2D2 differs from that catalyzed by human P450 2D6. [Journal Article]
- XXenobiotica 2019 Jun 14; :1-9
- 1. Propafenone, an antiarrhythmic drug, is a typical human cytochrome P450 (P450) 2D6 substrate used in preclinical studies. Here, propafenone oxidation by mammalian liver microsomes was investigated…
1. Propafenone, an antiarrhythmic drug, is a typical human cytochrome P450 (P450) 2D6 substrate used in preclinical studies. Here, propafenone oxidation by mammalian liver microsomes was investigated in vitro. 2. Liver microsomes from humans and marmosets preferentially mediated propafenone 5-hydroxylation, minipig, rat and mouse livers primarily mediated 4'-hydroxylation, but cynomolgus monkey and dog liver microsomes differently mediated N-despropylation. 3. Quinine, ketoconazole or anti-P450 2D antibodies suppressed propafenone 4'/5-hydroxylation in human and rat liver microsomes. Pretreatments with β-naphthoflavone or dexamethasone increased N-despropylation in rat livers. 4. Recombinant rat P450 2D2 efficiently catalysed propafenone 4'-hydroxylation in a substrate inhibition manner, comparable to rat liver microsomes, while human P450 2D6 displayed propafenone 5-hydroxylation. Human and rat P450 1A, 2C and 3A enzymes mediated propafenone N-despropylation with high capacities. 5. Carbon-4' of propafenone docked favourably into the active site of P450 2D2 based on an in silico model; in contrast, carbon-5 of propafenone docked into human P450 2D6. 6. These results suggest that the major roles of individual P450 2D enzymes in regioselective hydroxylations of propafenone differ between human and rat livers, while the minor roles of P450 1A, 2C and 3A enzymes for propafenone N-despropylation are similar in livers of both species.