scholarly journals MiR-223-3p as a Novel MicroRNA Regulator of Expression of Voltage-Gated K+ Channel Kv4.2 in Acute Myocardial Infarction

2016 ◽  
Vol 39 (1) ◽  
pp. 102-114 ◽  
Author(s):  
Xue Liu ◽  
Ying Zhang ◽  
Weijie Du ◽  
Haihai Liang ◽  
Hua He ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Acute Myocardial Infarction ◽  
Protein Level ◽  
Neonatal Rat ◽  
Luciferase Assay ◽  
K Channel ◽  
Voltage Gated ◽  
Ventricular Cells ◽  
Repressive Effect ◽  
Ischemic Arrhythmias

Background/Aims: Acute myocardial infarction (AMI) is a devastating cardiovascular disease with a high rate of morbidity and mortality, partly due to enhanced arrhythmogenicity. MicroRNAs (miRNAs) have been shown to participate in the regulation of cardiac ion channels and the associated arrhythmias. The purpose of this study was to test our hypothesis that miR-223-3p contributes to the electrical disorders in AMI via modulating KCND2, the gene encoding voltage-gated channel Kv4.2 that carries transient outward K+ current Ito. Methods: AMI model was established in male Sprague-Dawley (SD) rats by left anterior descending artery (LAD) ligation. Evans blue and TTC staining was used to measure infarct area. Ito was recorded in isolated ventricular cardiomyocytes or cultured neonatal rat ventricular cells (NRVCs) by whole-cell patch-clamp techniques. Western blot analysis was employed to detect the protein level of Kv4.2 and real-time RT-PCR to determine the transcript level of miR-223-3p. Luciferase assay was used to examine the interaction between miR-223-3p and KCND2 in cultured NRVCs. Results: Expression of miR-223-3p was remarkably upregulated in AMI relative to sham control rats. On the contrary, the protein level of Kv4.2 and Ito density were significantly decreased in AMI. Consistently, transfection of miR-223-3p mimic markedly reduced Kv4.2 protein level and Ito current in cultured NRVCs. Co-transfection of AMO-223-3p (an antisense inhibitor of miR-223-3p) reversed the repressive effect of miR-223-3p. Luciferase assay showed that miR-223-3p, but not the negative control, substantially suppressed the luciferase activity, confirming the direct binding of miR-223-3p to the seed site within the KCND2 sequence. Finally, direct intramuscular injection of AMO-223-3p into the ischemic myocardium to knockdown endogenous miR-223-3p decreased the propensity of ischemic arrhythmias. Conclusions: Upregulation of miR-223-3p in AMI repressed the expression of KCND2/Kv4.2 resulting in reduction of Ito density that can cause APD prolongation and promote arrhythmias in AMI, and therefore knockdown of endogenous miR-223-3p might be considered a new approach for antiarrhythmic therapy of ischemic arrhythmias.

Carvedilol reduces myocardial no-reflow by decreasing endothelin-1 via activation of the ATP-sensitive K+ channel

Perfusion ◽  
2008 ◽  
Vol 23 (2) ◽  
pp. 111-115 ◽  
Author(s):  
JL Zhao ◽  
YJ Yang ◽  
WD Pei ◽  
YH Sun ◽  
M Zhai ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Acute Myocardial Infarction ◽  
Channel Blocker ◽  
Contrast Echocardiography ◽  
Study Groups ◽  
K Channel ◽  
Control Group ◽  
Myocardial Tissue ◽  
Endothelin 1 ◽  
No Reflow

It has been verified that carvedilol can attenuate myocardial no-reflow. However, the effects of carvedilol on adenosine triphosphate-sensitive K+ (KATP) channel and endothelin-1 (ET-1) are unknown. Forty mini-swines were randomized into 5 study groups: 8 control, 8 carvedilol pretreatment, 8 glibenclamide (KATP channel blocker)-treated, 8 carvedilol and glibenclamide-pre-treated and 8 sham-operated. An acute myocardial infarction(AMI) and reperfusion model was created with a three-hour occlusion of the left anterior descending coronary artery followed by one-hour reperfusion. Compared with the control group, carvedilol significantly decreased the area of no-reflow (myocardial contrast echocardiography: from 78.5±4.5% to 24.9±4.1%, pathological means: from 82.3±1.9% to 25.8±4.3% of ligation area, respectively; all p < 0.01) and reduced necrosis size from 98.5±1.3% to 74.4±4.7% of ligation area, p < 0.05). It also decreased plasma ET-1 and myocardial tissue ET-1. However, glibenclamide abrogated the protective effect of carvedilol. The beneficial effect of carvedilol on myocardial no-reflow could be due to its effect on ET-1 via the activation of the KATP channel.

scholarly journals Circulating Long Noncoding RNA HOTAIR is an Essential Mediator of Acute Myocardial Infarction

2017 ◽  
Vol 44 (4) ◽  
pp. 1497-1508 ◽  
Author(s):  
Lu Gao ◽  
Yuan Liu ◽  
Sen Guo ◽  
Rui Yao ◽  
Leiming Wu ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Acute Myocardial Infarction ◽  
Coronary Artery ◽  
Neonatal Rat ◽  
Luciferase Reporter ◽  
Coronary Artery Ligation ◽  
Healthy Controls ◽  
Artery Ligation ◽  
Cultured Cardiomyocytes

Background/Aims: Acute myocardial infarction (AMI) is one of the leading causes of death in the world. However, specific diagnostic biomarkers have not been fully determined, and candidate regulatory targets for AMI have not been identified to date. Long noncoding RNAs (lncRNAs) are a class of RNA molecules that have diverse regulatory functions during embryonic development, normal life, and disease in higher organisms. However, research on the role of lncRNAs in cardiovascular diseases, particularly AMI, is still in its infancy. HOX antisense intergenic RNA (HOTAIR), a 2.2 kb lncRNA, was initially described as a modulator of HOX gene expression. Recent studies have illustrated the important role of HOTAIR in cancer progression, but few studies have reported its function in cardiac disease, including AMI. In the current study, we aimed to detect the expression of HOTAIR during AMI and to explore its function in hypoxia-induced cardiomyocyte injury in neonatal cardiomyocytes. Methods: In 50 consecutively enrolled AMI patients, we examined the serum expression levels of HOTAIR and analysed its correlation with cardiac troponin I (cTnI) expression. Another 50 age- and sex-matched subjects served as healthy controls. Next, the HOTAIR expression was detected in the serum from C57BL/6J mice subjected to coronary artery ligation and in neonatal rat cardiomyocytes induced by hypoxia. Cultured cardiomyocytes apoptosis were measured by terminal deoxynucleotide transferase dUTP nick end labelling (TUNEL) staining. A search for miRNAs that had complementary base paring with HOTAIR was performed utilizing an online software program, and the interaction between miR-1 and HOTAIR was examined using a luciferase reporter assay. Results: Our study revealed that HOTAIR expression was significantly decreased in the serum of AMI patients compared with that of the healthy controls. Similarly, we observed that HOTAIR was downregulated in the serum of mice subjected to coronary artery ligation and in cultured cardiomyocytes exposed to hypoxia. Furthermore, we observed that the adenovirus vector-driven overexpression of HOTAIR dramatically limited hypoxia-induced myocyte apoptosis, whereas knockdown HOTAIR by AdshHOTAIR (adenoviral short hairpin HOTAIR) exhibited the opposite phenotype. Mechanistically, we discovered that the cardioprotective function of HOTAIR is partly based on the negative regulation of miR-1. Conclusions: Taken together, the results of our study suggest that HOTAIR is a protective factor for cardiomyocytes and that the plasma concentration of HOTAIR may serve as a biomarker for human AMI diagnosis.

Potassium channel block does not affect metabolic responses of brown fat cells

1992 ◽  
Vol 262 (3) ◽  
pp. C678-C681 ◽  
Author(s):  
P. A. Pappone ◽  
M. T. Lucero
Keyword(s):  
Potassium Channels ◽  
Metabolic Response ◽  
Brown Fat ◽  
Neonatal Rat ◽  
K Channel ◽  
Fat Cells ◽  
Adrenergic Stimulation ◽  
K Channels ◽  
Voltage Gated ◽  
Calcium Activated Potassium Channels

Hormonally stimulated brown fat cells are capable of extremely high metabolic rates, making them an excellent system in which to examine the role of plasma membrane ion channels in cell metabolism. We have previously shown that brown fat cell membranes have both voltage-gated and calcium-activated potassium channels (Voltage-gated potassium channels in brown fat cells. J. Gen. Physiol. 93: 451-472, 1989; Membrane responses to norepinephrine in cultured brown fat cells. J. Gen. Physiol. 95: 523-544, 1990). Currents through both the voltage-activated potassium channels, IK,V, and the calcium-activated potassium channels, IK,Ca, can be blocked by the membrane-impermeant K channel blocker tetraethylammonium (TEA). We used microcalorimetric measurements from isolated neonatal rat brown fat cells to assess the role these potassium conductances play in the metabolic response of brown fat cells to adrenergic stimulation. Concentrations of TEA as high as 50 mM, sufficient to block approximately 95% of IK,V and 100% of IK,Ca, had no effect on norepinephrine-stimulated heat production. These results show that neither voltage-gated nor calcium-activated K channels are necessary for a maximal thermogenic response in brown fat cells and suggest that K channels are not involved in maintaining cellular homeostasis during periods of high metabolic activity.

scholarly journals THE CORRELATION OF THE SERUM C-REACTIVE PROTEIN LEVEL WITH THE C-REACTIVE PROTEIN GENE T-757C POLYMORPHISM AND RISK OF ACUTE MYOCARDIAL INFARCTION

Heart ◽  
2012 ◽  
Vol 98 (Suppl 2) ◽  
pp. E187.4-E188
Author(s):  
He Guo-Ping ◽  
Yang Hai-Tao ◽  
Qi Chuan-Ping ◽  
Xu Lian-Hong ◽  
Qian Yi-Chao ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Acute Myocardial Infarction ◽  
Protein Level ◽  
Protein Gene ◽  
C Reactive Protein ◽  
Reactive Protein

Rat Models of Ventricular Fibrillation Following Acute Myocardial Infarction

2017 ◽  
Vol 22 (6) ◽  
pp. 514-528 ◽  
Author(s):  
Laura A. Hundahl ◽  
Jacob Tfelt-Hansen ◽  
Thomas Jespersen
Keyword(s):  
Myocardial Infarction ◽  
Acute Myocardial Infarction ◽  
Animal Models ◽  
Cardiac Death ◽  
Ventricular Arrhythmias ◽  
Acute Ischemia ◽  
Acute Setting ◽  
Advantages And Disadvantages ◽  
Underlying Mechanisms ◽  
Ischemic Arrhythmias

A number of animal models have been designed in order to unravel the underlying mechanisms of acute ischemia-induced arrhythmias and to test compounds and interventions for antiarrhythmic therapy. This is important as acute myocardial infarction (AMI) continues to be the major cause of sudden cardiac death, and we are yet to discover safe and effective treatments of the lethal arrhythmias occurring in the acute setting. Animal models therefore continue to be relevant for our understanding and treatment of acute ischemic arrhythmias. This review discusses the applicability of the rat as a model for ventricular arrhythmias occurring during the acute phase of AMI. It provides a description of models developed, advantages and disadvantages of rats, as well as an overview of the most important interventions investigated and the relevance for human pathophysiology.

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