scholarly journals Ionic bases for electrical remodeling of the canine cardiac ventricle

2013 ◽  
Vol 305 (3) ◽  
pp. H410-H419 ◽  
Author(s):  
Darwin Jeyaraj ◽  
Xiaoping Wan ◽  
Eckhard Ficker ◽  
Julian E. Stelzer ◽  
Isabelle Deschenes ◽  
...  
Keyword(s):  
Ion Channels ◽  
Ion Channel ◽  
Phase 1 ◽  
Myocardial Strain ◽  
Ionic Currents ◽  
Left Ventricular ◽  
Electrical Remodeling ◽  
Cardiac Ventricle ◽  
Ionic Mechanisms ◽  
Ventricular Electrical Remodeling

Emerging evidence suggests that ventricular electrical remodeling (VER) is triggered by regional myocardial strain via mechanoelectrical feedback mechanisms; however, the ionic mechanisms underlying strain-induced VER are poorly understood. To determine its ionic basis, VER induced by altered electrical activation in dogs undergoing left ventricular pacing ( n = 6) were compared with unpaced controls ( n = 4). Action potential (AP) durations (APDs), ionic currents, and Ca2+ transients were measured from canine epicardial myocytes isolated from early-activated (low strain) and late-activated (high strain) left ventricular regions. VER in the early-activated region was characterized by minimal APD prolongation, but marked attenuation of the AP phase 1 notch attributed to reduced transient outward K+ current. In contrast, VER in the late-activated region was characterized by significant APD prolongation. Despite marked APD prolongation, there was surprisingly minimal change in ion channel densities but a twofold increase in diastolic Ca2+. Computer simulations demonstrated that changes in sarcolemmal ion channel density could only account for attenuation of the AP notch observed in the early-activated region but failed to account for APD remodeling in the late-activated region. Furthermore, these simulations identified that cytosolic Ca2+ accounted for APD prolongation in the late-activated region by enhancing forward-mode Na+/Ca2+ exchanger activity, corroborated by increased Na+/Ca2+ exchanger protein expression. Finally, assessment of skinned fibers after VER identified altered myofilament Ca2+ sensitivity in late-activated regions to be associated with increased diastolic levels of Ca2+. In conclusion, we identified two distinct ionic mechanisms that underlie VER: 1) strain-independent changes in early-activated regions due to remodeling of sarcolemmal ion channels with no changes in Ca2+ handling and 2) a novel and unexpected mechanism for strain-induced VER in late-activated regions in the canine arising from remodeling of sarcomeric Ca2+ handling rather than sarcolemmal ion channels.

Ion Channel Permeation and Selectivity

2019 ◽  
Author(s):  
Juan J. Nogueira ◽  
Ben Corry
Keyword(s):  
Ion Channels ◽  
Ion Channel ◽  
Ion Selectivity ◽  
Ionic Currents ◽  
Biological Processes ◽  
Ion Permeation ◽  
Voltage Gated ◽  
Physical Mechanisms ◽  
Theoretical Approaches ◽  
Mechanistic Insight

Many biological processes essential for life rely on the transport of specific ions at specific times across cell membranes. Such exquisite control of ionic currents, which is regulated by protein ion channels, is fundamental for the proper functioning of the cells. It is not surprising, therefore, that the mechanism of ion permeation and selectivity in ion channels has been extensively investigated by means of experimental and theoretical approaches. These studies have provided great mechanistic insight but have also raised new questions that are still unresolved. This chapter first summarizes the main techniques that have provided significant knowledge about ion permeation and selectivity. It then discusses the physical mechanisms leading to ion permeation and the explanations that have been proposed for ion selectivity in voltage-gated potassium, sodium, and calcium channels.

VOCCs and TREK-1 ion channel expression in human tenocytes

2007 ◽  
Vol 292 (3) ◽  
pp. C1053-C1060 ◽  
Author(s):  
Merzesh Magra ◽  
Steven Hughes ◽  
Alicia J. El Haj ◽  
Nicola Maffulli
Keyword(s):  
Ion Channels ◽  
Ion Channel ◽  
Ionic Currents ◽  
Cell Types ◽  
Functional Expression ◽  
Tissue Cell ◽  
Pharmacological Management ◽  
Whole Cell ◽  
Voltage Gated ◽  
Channel Expression

Mechanosensitive and voltage-gated ion channels are known to perform important roles in mechanotransduction in a number of connective tissues, including bone and muscle. It is hypothesized that voltage-gated and mechanosensitive ion channels also may play a key role in some or all initial responses of human tenocytes to mechanical stimulation. However, to date there has been no direct investigation of ion channel expression by human tenocytes. Human tenocytes were cultured from patellar tendon samples harvested from five patients undergoing routine total knee replacement surgery (mean age: 66 yr; range: 63–73 yr). RT-PCR, Western blotting, and whole cell electrophysiological studies were performed to investigate the expression of different classes of ion channels within tenocytes. Human tenocytes expressed mRNA and protein encoding voltage-operated calcium channel (VOCC) subunits (Ca α1A, Ca α1C, Ca α1D, Ca α2δ1) and the mechanosensitive tandem pore domain potassium channel (2PK+) TREK-1. They exhibit whole cell currents consistent with the functional expression of these channels. In addition, other ionic currents were detected within tenocytes consistent with the expression of a diverse array of other ion channels. VOCCs and TREK channels have been implicated in mechanotransduction signaling pathways in numerous connective tissue cell types. These mechanisms may be present in human tenocytes. In addition, human tenocytes may express other channel currents. Ion channels may represent potential targets for the pharmacological management of chronic tendinopathies.

scholarly journals Impact of recanalization of chronic total occlusion on left ventricular electrical remodeling

2019 ◽  
Vol 42 (6) ◽  
pp. 712-721 ◽  
Author(s):  
Kennosuke Yamashita ◽  
Wataru Igawa ◽  
Morio Ono ◽  
Takehiko Kido ◽  
Toshitaka Okabe ◽  
...  
Keyword(s):  
Chronic Total Occlusion ◽  
Left Ventricular ◽  
Electrical Remodeling ◽  
Total Occlusion ◽  
Ventricular Electrical Remodeling

Computer simulation of ECG manifestations of left ventricular electrical remodeling

2012 ◽  
Vol 45 (6) ◽  
pp. 630-634 ◽  
Author(s):  
Ljuba Bacharova ◽  
Vavrinec Szathmary ◽  
Mark Potse ◽  
Anton Mateasik
Keyword(s):  
Computer Simulation ◽  
Left Ventricular ◽  
Electrical Remodeling ◽  
Ventricular Electrical Remodeling

scholarly journals Functional ion channels in mouse cardiac c-kit+ cells

2010 ◽  
Vol 298 (5) ◽  
pp. C1109-C1117 ◽  
Author(s):  
Yi Han ◽  
Jia-Dao Chen ◽  
Zu-Mei Liu ◽  
Yuan Zhou ◽  
Jia-Hong Xia ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Ion Channels ◽  
Ion Channel ◽  
Ionic Currents ◽  
Delayed Rectifier ◽  
Rt Pcr ◽  
Electrophysiological Properties ◽  
Cell Progression ◽  
A Cell ◽  
Channel Currents

Cardiac c-kit+ cells are generally believed to be the major population of stem/progenitor cells in the heart and can be used as a cell source for cardiomyoplasty; however, the cellular electrophysiological properties are not understood in this type of cells. The present study was designed to investigate functional ion channels in undifferentiated mouse cardiac c-kit+ cells using approaches of whole cell patch voltage clamp, RT-PCR, and cell proliferation assay. It was found that three types of ionic currents were present in mouse cardiac c-kit+ cells, including a delayed rectifier K+ current (IKDR) inhibited by 4-aminopyridine (4-AP), an inward rectifier K+ current ( IKir) decreased by Ba2+, and a volume-sensitive chloride current ( ICl.vol) inhibited by 5-nitro-1-(3-phenylpropylamino) benzoic acid (NPPB). RT-PCR revealed that the corresponding ion channel genes, Kv1.1, Kv1.2, and Kv1.6 (for IKDR), Kir.1.1, Kir2.1, and Kir2.2 (likely responsible for IKir), and Clcn3 (for ICl.vol), were significant in mouse cardiac c-kit+ cells. The inhibition of ICl.vol with NPPB and niflumic acid, but not IKDR with 4-AP and tetraethylammonium, reduced cell proliferation and accumulated the cell progression at G0/G1 phase in mouse cardiac c-kit+ cells. Our results demonstrate that three types of functional ion channel currents (i.e., IKDR, IKir, and ICl.vol) are present in mouse cardiac c-kit+ cells, and ICl.vol participates in regulating cell proliferation.

scholarly journals Predictive values of multiple non-invasive markers for myocardial fibrosis in hypertrophic cardiomyopathy patients with preserved ejection fraction

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yumin Li ◽  
Jia Liu ◽  
Yukun Cao ◽  
Xiaoyu Han ◽  
Guozhu Shao ◽  
...  
Keyword(s):  
Hypertrophic Cardiomyopathy ◽  
Ejection Fraction ◽  
Myocardial Fibrosis ◽  
Troponin I ◽  
Myocardial Strain ◽  
Left Ventricular ◽  
Preserved Ejection Fraction ◽  
Predictive Values ◽  
Non Invasive ◽  
Potential Biomarker

AbstractMyocardial fibrosis assessed by late gadolinium enhancement (LGE) on cardiovascular magnetic resonance (CMR) is associated with cardiovascular outcomes in hypertrophic cardiomyopathy (HCM) patients, but little is known about the utility of non-invasive markers for detecting LGE. This study aims to explore the association between cardiac-specific biomarkers, CMR myocardial strain, left ventricular (LV) hypertrophy and LGE in HCM patients with preserved ejection fraction (EF) and investigate the predictive values of these indexes for LGE. We recruited 33 healthy volunteers and 86 HCM patients with preserved EF to undergo contrast-enhanced CMR examinations. In total, 48 of 86 HCM patients had the presence of LGE. The LGE-positive patients had significant higher serum high-sensitivity cardiac troponin I (hs-cTnI) and N-terminal pro b-type natriuretic peptide (Nt-proBNP) levels and lower global longitudinal (GLS) and circumferential (GCS) strains than the LGE-negative group. The LGE% was independently associated with the Nt-proBNP levels, GCS, LV end-diastolic maximum wall thickness (MWT) and beta-blocker treatment. In the receiver operating characteristic curve analysis, the combined parameters of Nt-proBNP ≥ 108.00 pg/mL and MWT ≥ 17.30 mm had good diagnostic performance for LGE, with a specificity of 81.25% and sensitivity of 70.00%. These data indicate that serum Nt-proBNP is a potential biomarker associated with LGE% and, combined with MWT, were useful for identifying myocardial fibrosis in HCM patients with preserved EF. Additionally, LV GCS may be a more sensitive indicator for reflecting the presence of myocardial fibrosis than GLS.

GW24-e1717 Assessment on the changes of myocardial strain rate and aneurysm volume of left ventricular aneurysm in a rabbit model

Heart ◽  
2013 ◽  
Vol 99 (Suppl 3) ◽  
pp. A261.2-A261 ◽  
Author(s):  
Mu YuMing ◽  
Zhai Hong ◽  
Guliqiman Hhuojiaabudula ◽  
Wang Chunmei ◽  
Han Wei ◽  
...  
Keyword(s):  
Strain Rate ◽  
Myocardial Strain ◽  
Rabbit Model ◽  
Left Ventricular ◽  
Left Ventricular Aneurysm ◽  
Ventricular Aneurysm ◽  
Aneurysm Volume
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