Cellular mechanisms of ventricular arrhythmias in ischemia

Life-threatening ventricular arrhythmias are the main clinical burden in patients with hypertrophic cardiomyopathy (HCM), and frequently occur in young patients with mild structural disease. While massive hypertrophy, fibrosis and microvascular ischemia are the main mechanisms underlying sustained reentry-based ventricular arrhythmias in advanced HCM, cardiomyocyte-based functional arrhythmogenic mechanisms are likely prevalent at earlier stages of the disease. In this review, we will describe studies conducted in human surgical samples from HCM patients, transgenic animal models and human cultured cell lines derived from induced pluripotent stem cells. Current pieces of evidence concur to attribute the increased risk of ventricular arrhythmias in early HCM to different cellular mechanisms. The increase of late sodium current and L-type calcium current is an early observation in HCM, which follows post-translation channel modifications and increases the occurrence of early and delayed afterdepolarizations. Increased myofilament Ca2+ sensitivity, commonly observed in HCM, may promote afterdepolarizations and reentry arrhythmias with direct mechanisms. Decrease of K+-currents due to transcriptional regulation occurs in the advanced disease and contributes to reducing the repolarization-reserve and increasing the early afterdepolarizations (EADs). The presented evidence supports the idea that patients with early-stage HCM should be considered and managed as subjects with an acquired channelopathy rather than with a structural cardiac disease.

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Mechanisms Underlying the Actions of Antidepressant and Antipsychotic Drugs That Cause Sudden Cardiac Arrest

Arrhythmia & Electrophysiology Review ◽

10.15420/aer.2018.29.2 ◽

2018 ◽

Vol 7 (3) ◽

pp. 199 ◽

Cited By ~ 8

Author(s):

Serge Sicouri ◽

Charles Antzelevitch ◽

◽

...

Keyword(s):

Sudden Cardiac Death ◽

Brugada Syndrome ◽

Cardiac Death ◽

Ventricular Arrhythmias ◽

Antipsychotic Drugs ◽

Sudden Cardiac Arrest ◽

Torsade De Pointes ◽

Antidepressant Drugs ◽

Cellular Mechanisms ◽

Genetic And Environmental Factors

A number of antipsychotic and antidepressant drugs are known to increase the risk of ventricular arrhythmias and sudden cardiac death. Based largely on a concern over the development of life-threatening arrhythmias, a number of antipsychotic drugs have been temporarily or permanently withdrawn from the market or their use restricted. While many antidepressants and antipsychotics have been linked to QT prolongation and the development of torsade de pointes arrhythmias, some have been associated with a Brugada syndrome phenotype and the development of polymorphic ventricular arrhythmias. This article examines the arrhythmic liability of antipsychotic and antidepressant drugs capable of inducing long QT and/or Brugada syndrome phenotypes. The goal of this article is to provide an update on the ionic and cellular mechanisms thought to be involved in, and the genetic and environmental factors that predispose to, the development of cardiac arrhythmias and sudden cardiac death among patients taking antidepressant and antipsychotic drugs that are in clinical use.

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Cellular mechanisms of ventricular arrhythmias in a mouse model of Timothy syndrome (long QT syndrome 8)

Journal of Molecular and Cellular Cardiology ◽

10.1016/j.yjmcc.2013.10.021 ◽

2014 ◽

Vol 66 ◽

pp. 63-71 ◽

Cited By ~ 23

Author(s):

Benjamin M.L. Drum ◽

Rose E. Dixon ◽

Can Yuan ◽

Edward P. Cheng ◽

Luis F. Santana

Keyword(s):

Mouse Model ◽

Long Qt Syndrome ◽

Ventricular Arrhythmias ◽

Timothy Syndrome ◽

Cellular Mechanisms ◽

Long Qt ◽

Qt Syndrome

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Catecholaminergic-induced arrhythmias in failing cardiomyocytes associated with human HRCS96A variant overexpression

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.01153.2010 ◽

2011 ◽

Vol 301 (4) ◽

pp. H1588-H1595 ◽

Cited By ~ 15

Author(s):

Peidong Han ◽

Wenfeng Cai ◽

Yanru Wang ◽

Chi Keung Lam ◽

Demetrios A. Arvanitis ◽

...

Keyword(s):

Sarcoplasmic Reticulum ◽

Calcium Binding ◽

Ventricular Arrhythmias ◽

Genetic Variant ◽

Cellular Mechanisms ◽

Healthy Human ◽

Adult Rat ◽

Postmyocardial Infarction ◽

Life Threatening ◽

Infected Cells

The histidine-rich calcium binding protein (HRC) Ser96Ala polymorphism was shown to correlate with ventricular arrhythmias and sudden death only in dilated cardiomyopathy patients but not in healthy human carriers. In the present study, we assessed the molecular and cellular mechanisms underlying human arrhythmias by adenoviral expression of the human wild-type (HRCWT) or mutant HRC (HRCS96A) in adult rat ventricular cardiomyocytes. Total HRC protein was increased by ∼50% in both HRCWT- and HRCS96A-infected cells. The HRCS96A mutant exacerbated the inhibitory effects of HRCWT on the amplitude of Ca2+ transients, prolongation of Ca2+ decay time, and caffeine-induced sarcoplasmic reticulum Ca2+ release. Consistent with these findings, HRCS96A reduced maximal sarcoplasmic reticulum calcium uptake rate to a higher extent than HRCWT. Furthermore, the frequency of spontaneous Ca2+ sparks, which was reduced by HRCWT, was increased by mutant HRCS96A under resting conditions although there were no spontaneous Ca2+ waves under stress conditions. However, expression of the HRCS96A genetic variant in cardiomyocytes from a rat model of postmyocardial infarction heart failure induced dramatic disturbances of rhythmic Ca2+ transients. These findings indicate that the HRC Ser96Ala variant increases the propensity of arrhythmogenic Ca2+ waves in the stressed failing heart, suggesting a link between this genetic variant and life-threatening ventricular arrhythmias in human carriers.

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Vascular adaptations to hypoxia: molecular and cellular mechanisms regulating vascular tone

Essays in Biochemistry ◽

10.1042/bse0430105 ◽

2007 ◽

Vol 43 ◽

pp. 105-120 ◽

Cited By ~ 8

Author(s):

Michael L. Paffett ◽

Benjimen R. Walker

Keyword(s):

Vascular Tone ◽

Cellular Proliferation ◽

Hypoxic Pulmonary Vasoconstriction ◽

Hypoxia Inducible Factor ◽

Systemic Circulation ◽

Cellular Mechanisms ◽

Hypoxia Inducible Factor 1 ◽

Pulmonary Vasoconstriction ◽

Adaptive Mechanisms ◽

Adaptive Processes

Several molecular and cellular adaptive mechanisms to hypoxia exist within the vasculature. Many of these processes involve oxygen sensing which is transduced into mediators of vasoconstriction in the pulmonary circulation and vasodilation in the systemic circulation. A variety of oxygen-responsive pathways, such as HIF (hypoxia-inducible factor)-1 and HOs (haem oxygenases), contribute to the overall adaptive process during hypoxia and are currently an area of intense research. Generation of ROS (reactive oxygen species) may also differentially regulate vascular tone in these circulations. Potential candidates underlying the divergent responses between the systemic and pulmonary circulations may include Nox (NADPH oxidase)-derived ROS and mitochondrial-derived ROS. In addition to alterations in ROS production governing vascular tone in the hypoxic setting, other vascular adaptations are likely to be involved. HPV (hypoxic pulmonary vasoconstriction) and CH (chronic hypoxia)-induced alterations in cellular proliferation, ionic conductances and changes in the contractile apparatus sensitivity to calcium, all occur as adaptive processes within the vasculature.

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Flavonoids in adipose tissue inflammation and atherosclerosis: one arrow, two targets

Clinical Science ◽

10.1042/cs20200356 ◽

2020 ◽

Vol 134 (12) ◽

pp. 1403-1432 ◽

Cited By ~ 2

Author(s):

Manal Muin Fardoun ◽

Dina Maaliki ◽

Nabil Halabi ◽

Rabah Iratni ◽

Alessandra Bitto ◽

...

Keyword(s):

Adipose Tissue ◽

Fruits And Vegetables ◽

Metabolic Diseases ◽

Therapeutic Agents ◽

Adipose Tissue Inflammation ◽

Cellular Mechanisms ◽

Tissue Inflammation ◽

Cholesterol Levels ◽

Naturally Occurring ◽

Pro Inflammatory Cytokines

Abstract Flavonoids are polyphenolic compounds naturally occurring in fruits and vegetables, in addition to beverages such as tea and coffee. Flavonoids are emerging as potent therapeutic agents for cardiovascular as well as metabolic diseases. Several studies corroborated an inverse relationship between flavonoid consumption and cardiovascular disease (CVD) or adipose tissue inflammation (ATI). Flavonoids exert their anti-atherogenic effects by increasing nitric oxide (NO), reducing reactive oxygen species (ROS), and decreasing pro-inflammatory cytokines. In addition, flavonoids alleviate ATI by decreasing triglyceride and cholesterol levels, as well as by attenuating inflammatory mediators. Furthermore, flavonoids inhibit synthesis of fatty acids and promote their oxidation. In this review, we discuss the effect of the main classes of flavonoids, namely flavones, flavonols, flavanols, flavanones, anthocyanins, and isoflavones, on atherosclerosis and ATI. In addition, we dissect the underlying molecular and cellular mechanisms of action for these flavonoids. We conclude by supporting the potential benefit for flavonoids in the management or treatment of CVD; yet, we call for more robust clinical studies for safety and pharmacokinetic values.

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