Abnormal cardiac ryanodine receptor (RyR2) function is recognized as an important factor in the pathogenesis of heart failure (HF). However, specific molecular causes underlying RyR2 defects HF remain poorly understood. In present study, we used a canine model chronic to test hypothesis that HF-related alterations are caused by posttranslational modification reactive oxygen species generated failing heart. Experimental approaches included imaging cytosolic ([Ca(2+)](c)) and sarcoplasmic...

MicroRNAs are small endogenous noncoding RNAs that regulate protein expression by hybridization to imprecise complementary sequences of target mRNAs. Changes in abundance muscle-specific microRNA, miR-1 , have been implicated cardiac disease, including arrhythmia and heart failure. However, the specific molecular targets cellular mechanisms involved action only beginning emerge. In this study we investigated effects increased on excitation–contraction coupling Ca 2+ cycling rat ventricular...

Adaptation of single cardiac ryanodine receptor (RyR) channels was demonstrated by application the caged calcium ion (Ca 2+ ) methodology. In contrast to conventional desensitization found in surface membrane ligand-gated channels, RyR adapted maintained Ca stimuli, preserving their ability respond a second (larger) stimulus. adaptation may represent molecular control mechanism for smoothly graded -induced release heart and be fundamental feature including inositol trisphosphate receptor,...

Calsequestrin is a high-capacity Ca-binding protein expressed inside the sarcoplasmic reticulum (SR), an intracellular Ca release and storage organelle in muscle. Mutations cardiac calsequestrin gene ( CSQ2 ) have been linked to arrhythmias sudden death. We used Ca-imaging patch-clamp methods combination with adenoviral transfer strategies explore function of adult rat heart cells. By increasing or decreasing levels, we showed that not only determines capacity SR but also positively controls...

Despite extensive research, the mechanisms responsible for graded nature and early termination of Ca 2+ -induced release (CICR) from sarcoplasmic reticulum (SR) in cardiac muscle remain poorly understood. Suggested include cytosolic -dependent inactivation/adaptation luminal deactivtion SR channels/ryanodine receptors (RyRs). To explore importance versus regulatory controlling CICR, we assessed impact intra-SR buffering on global local properties patch-clamped or permeabilized rat...

Four distinct mutations in the human cardiac calsequestrin gene (CASQ2) have been linked to catecholaminergic polymorphic ventricular tachycardia (CPVT). The mechanisms leading clinical phenotype are still poorly understood because only 1 CASQ2 mutation has characterized vitro.We identified a homozygous 16-bp deletion at position 339 354 frame shift and stop codon after 5aa (CASQ2(G112+5X)) child with stress-induced arrest. same was also association novel point (CASQ2(L167H)) highly...

Diminished Ca release from the sarcoplasmic reticulum (SR) is an important contributor to impaired contractility of failing heart. Despite extensive effort, underlying causes abnormal SR in heart failure (HF) remain unknown. We used a combination simultaneous imaging cytosolic and intraluminal [Ca] isolated cardiomyocytes recordings single-ryanodine receptor (RyR) channels reconstituted into lipid bilayers investigate alterations intracellular handling experimental model chronic HF. found...

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a familial arrhythmogenic disorder associated with mutations in the cardiac ryanodine receptor ( RyR2 ) and calsequestrin CASQ2 genes. Previous vitro studies suggested that interact as parts of multimolecular Ca 2+ -signaling complex; however, direct evidence for such interactions their potential significance to myocardial function remain be determined. We identified novel mutation young female structurally normal heart...

AimsAlthough cardiac alternans is a known predictor of lethal arrhythmias, its underlying causes remain largely undefined in disease settings. The potential role of, and mechanisms responsible for, beat-to-beat alternations the amplitude systolic Ca2+ transients (Ca2+ alternans) was investigated canine post-myocardial infarction (MI) model sudden death (SCD).

In heart failure (HF), arrhythmogenic spontaneous sarcoplasmic reticulum (SR) Ca2+ release and afterdepolarizations in cardiac myocytes have been linked to abnormally high activity of ryanodine receptors (RyR2s) associated with enhanced phosphorylation the channel. However, specific molecular mechanisms underlying RyR2 hyperphosphorylation HF remain poorly understood. The objective current study was test hypothesis that expression muscle-specific microRNAs (miRNAs) underlies HF-related...

In heart failure (HF), abnormal myocyte Ca2+ handling has been implicated in cardiac arrhythmias and contractile dysfunction. the present study, we investigated relationships between handling, reduced contractility, enhanced arrhythmogenesis during HF progression a canine model of non-ischaemic HF. Key parameters were determined by measuring cytosolic intra-sarcoplasmic reticulum (SR) [Ca2+] isolated ventricular myocytes at different stages The was associated with an early continuous...

Loss-of-function mutations in Calsequestrin 2 (CASQ2) are associated with catecholaminergic polymorphic ventricular tachycardia (CPVT). CPVT patients also exhibit bradycardia and atrial arrhythmias for which the underlying mechanism remains unknown. We aimed to study sinoatrial node (SAN) dysfunction due loss of CASQ2.In vivo electrocardiogram (ECG) monitoring, vitro high-resolution optical mapping, confocal imaging intracellular Ca(2+) cycling, 3D immunohistology were performed wild-type...

Dilated cardiomyopathy is a major cause of progressive heart failure. Utilization stem cell therapy offers potential means regenerating viable cardiac tissue. However, obstacle to the delivery and survival implanted cells in ischemic heart. To address this issue, we have developed biomimetic aligned nanofibrous patch characterized alignment function human inducible pluripotent derived cardiomyocytes (hiPSC-CMs) cultured on patch. This hiPSC-CMs seeded was compared with standard flat culture...

Voltage-gated Na(+) channels (Nav) are essential for myocyte membrane excitability and cardiac function. Nav current (INa) is a large-amplitude, short-duration spike generated by rapid channel activation followed immediately inactivation. However, even under normal conditions, small late component of INa (INa,L) persists because incomplete/failed inactivation subpopulation channels. Notably, INa,L directly linked with both congenital acquired disease states. The multifunctional...

Abstract Cardiac disease is associated with deleterious emission of mitochondrial reactive oxygen species (mito-ROS), as well enhanced oxidation and activity the sarcoplasmic reticulum (SR) Ca 2+ release channel, ryanodine receptor (RyR2). The transfer from SR via RyR2 to mitochondria thought play a key role in matching increased metabolic demand during stress. In this study, we investigated whether augmented results self-imposed exacerbation leak, altered SR-mitochondrial elevated mito-ROS...

Mutations in human cardiac calsequestrin (CASQ2), a high-capacity calcium-binding protein located the sarcoplasmic reticulum (SR), have recently been linked to effort-induced ventricular arrhythmia and sudden death (catecholaminergic polymorphic tachycardia). However, precise mechanisms through which these mutations affect SR function lead are presently unknown. In this study, we explored effect of adenoviral-directed expression canine CASQ2 carrying catecholaminergic tachycardia-linked...

1. We carried out confocal Ca2+ imaging in myocytes permeabilized with saponin 'internal' solutions containing: MgATP, EGTA and fluo-3 potassium salt. 2. Permeabilized exhibited spontaneous sparks waves similar to those observed intact loaded AM. 3. In the presence of 'low' [EGTA] (0.05 mM), arose regularly, even at relatively low [Ca2+] (50-100 nM, free). Increasing resulted decreased frequency propagation velocity waves. Propagating were completely abolished > 0.3 mM. 4. The increased as a...

1. Confocal microfluorometry was used to study the effects of tetracaine on spontaneous Ca2+ release from sarcoplasmic reticulum (SR) in isolated rat ventricular myocytes. 2. At low concentrations (0.25‐1.25 mM), caused an initial inhibition events (Ca2+ sparks) and waves, which followed by a gradual increase activity. The frequency magnitude sparks were first decreased then increased with respect control levels. high (> 1.25 abolished all forms release. 3. Exposure myocytes resulted SR...

The opportunistic pathogen Pseudomonas aeruginosa utilizes a cell density-dependent signalling phenomenon known as quorum sensing (QS) to regulate several virulence factors needed for infection. Acylated homoserine lactones, or autoinducers, are the primary signal molecules that mediate QS in P. aeruginosa. autoinducer N-3O-dodecanoyl-homoserine lactone (3O-C12) exerts effects on mammalian cells, including upregulation of pro-inflammatory mediators and induction apoptosis. However,...

Isolated diastolic dysfunction is found in almost half of asymptomatic patients with well-controlled diabetes and may precede heart failure. However, mechanisms that underlie during are not well understood. We tested the hypothesis isolated associated impaired myocardial Ca(2+) handling type 1 diabetes. Streptozotocin-induced diabetic rats were compared age-matched placebo-treated rats. Global left ventricular performance systolic function preserved animals. Diabetes-induced was evident on...