Effects of post-treatment electroacupuncture on ventricular monophasic action potential and cardiac function in a rat model of ischemia/reperfusion injury

2021 ◽  
pp. 096452842110392
Author(s):  
Jian Tang ◽  
Wenxin Ren ◽  
Yanqiu Liu ◽  
Hong Gao ◽  
Yuanliang Wang ◽  
...  
Keyword(s):  
Coronary Artery ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Action Potential ◽  
Cardiac Function ◽  
Ischemia Reperfusion ◽  
Left Ventricular ◽  
Post Treatment ◽  
Monophasic Action Potential ◽  
Coronary Artery Ligation

Background: To determine the effects of post-treatment electroacupuncture (EA) on the electrophysiological properties of ventricular muscle in rats with ischemia/reperfusion (IR) injury. Methods: Male Sprague–Dawley (SD) rats were randomly assigned into sham-operated (SH), IR and IR + EA groups ( n = 8 each). The IR model was generated by ligation of the left anterior descending (LAD) coronary artery for 30 min. After establishing the IR model, EA was administered at PC6 for 30 min while opening the coronary artery and allowing reperfusion for 30 min. Heart rate (HR), mean arterial pressure and monophasic action potential (MAP) of cardiac muscle in the outer membrane of the antetheca of the left ventricle before coronary artery ligation ( T0), after coronary artery ligation for 30 min ( T1) and after reperfusion for 30 min ( T2) were recorded. At the same time, ventricular electrophysiological parameters including ventricular effective refractory period (ERP), conduction velocity (CV) and ventricular fibrillation threshold (VFT) were measured. Then, the cardiac function and the levels of creatine kinase-muscle/brain (CK-MB) and cardiac troponin I (cTnI) were monitored. Based on these data, monophasic action potential amplitude (MAPA), the maximum depolarization velocity ( Vmax) and the MAP durations at 50% and 90% repolarization (MAPD50 and MAPD90) were calculated to determine the incidence of arrhythmia during reperfusion. Results: Compared with the SH group, the IR group showed an obviously decreased HR as well as reduced mean arterial pressure, Vmax, CV, ERP and MAPA. All indices of cardiac function except left ventricular end-diastolic pressure (LVEDP) decreased (i.e. ventricular systolic pressure (LVSP), left ventricular ejection fraction (LVEF), fractional shortening (FS) and rate of the ventricular pressure rise/drop (±dp/dt)). Furthermore, the MAPD50 and MAPD90 were prolonged, and the levels of CK-MB and cTnI increased ( p < 0.05). In comparison to the IR group, HR and the mean arterial pressure were increased. All indices of cardiac function except LVEDP increased (LVSP, LVEF, FS and ±dp/dt). Vmax, CV, ERP and MAPA were also increased in the IR + EA group. However, MAPD50 and MAPD90 were distinctly shortened, and the levels of CK-MB and cTnI decreased ( p < 0.05). There were no statistically significant differences in VFT between the three groups ( p > 0.05). Conclusion: EA post-treatment can relieve prolongation of repolarization and slowed depolarization of ventricular muscle during IR, thus decreasing the rate of incidence of reperfusion arrhythmia.

Breathing nitric oxide plus hydrogen gas reduces ischemia-reperfusion injury and nitrotyrosine production in murine heart

2013 ◽  
Vol 305 (4) ◽  
pp. H542-H550 ◽  
Author(s):  
Toshihiro Shinbo ◽  
Kenichi Kokubo ◽  
Yuri Sato ◽  
Shintaro Hagiri ◽  
Ryuji Hataishi ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Cardiac Function ◽  
Infarct Size ◽  
Ischemia Reperfusion Injury ◽  
Myocardial Dysfunction ◽  
Ischemia Reperfusion ◽  
Neutrophil Infiltration ◽  
Left Ventricular ◽  
Hydrogen Gas ◽  
Coronary Artery Ligation

Inhaled nitric oxide (NO) has been reported to decrease the infarct size in cardiac ischemia-reperfusion (I/R) injury. However, reactive nitrogen species (RNS) produced by NO cause myocardial dysfunction and injury. Because H2 is reported to eliminate peroxynitrite, it was expected to reduce the adverse effects of NO. In mice, left anterior descending coronary artery ligation for 60 min followed by reperfusion was performed with inhaled NO [80 parts per million (ppm)], H2 (2%), or NO + H2, starting 5 min before reperfusion for 35 min. After 24 h, left ventricular function, infarct size, and area at risk (AAR) were assessed. Oxidative stress associated with reactive oxygen species (ROS) was evaluated by staining for 8-hydroxy-2′-deoxyguanosine and 4-hydroxy-2-nonenal, that associated with RNS by staining for nitrotyrosine, and neutrophil infiltration by staining for granulocyte receptor-1. The infarct size/AAR decreased with breathing NO or H2 alone. NO inhalation plus H2 reduced the infarct size/AAR, with significant interaction between the two, reducing ROS and neutrophil infiltration, and improved the cardiac function to normal levels. Although nitrotyrosine staining was prominent after NO inhalation alone, it was eliminated after breathing a mixture of H2 with NO. Preconditioning with NO significantly reduced the infarct size/AAR, but not preconditioning with H2. In conclusion, breathing NO + H2 during I/R reduced the infarct size and maintained cardiac function, and reduced the generation of myocardial nitrotyrosine associated with NO inhalation. Administration of NO + H2 gases for inhalation may be useful for planned coronary interventions or for the treatment of I/R injury.

scholarly journals Attenuated muscle metaboreflex-induced increases in cardiac function in hypertension

2013 ◽  
Vol 305 (10) ◽  
pp. H1548-H1554 ◽  
Author(s):  
Javier A. Sala-Mercado ◽  
Marty D. Spranger ◽  
Rania Abu-Hamdah ◽  
Jasdeep Kaur ◽  
Matthew Coutsos ◽  
...  
Keyword(s):  
Cardiac Output ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Cardiac Function ◽  
Peripheral Resistance ◽  
Artery Occlusion ◽  
Left Ventricular ◽  
Exercise Intolerance ◽  
Muscle Metaboreflex ◽  
Cardiac Responses

Sympathoactivation may be excessive during exercise in subjects with hypertension, leading to increased susceptibility to adverse cardiovascular events, including arrhythmias, infarction, stroke, and sudden cardiac death. The muscle metaboreflex is a powerful cardiovascular reflex capable of eliciting marked increases in sympathetic activity during exercise. We used conscious, chronically instrumented dogs trained to run on a motor-driven treadmill to investigate the effects of hypertension on the mechanisms of the muscle metaboreflex. Experiments were performed before and 30.9 ± 4.2 days after induction of hypertension, which was induced via partial, unilateral renal artery occlusion. After induction of hypertension, resting mean arterial pressure was significantly elevated from 98.2 ± 2.6 to 141.9 ± 7.4 mmHg. The hypertension was caused by elevated total peripheral resistance. Although cardiac output was not significantly different at rest or during exercise after induction of hypertension, the rise in cardiac output with muscle metaboreflex activation was significantly reduced in hypertension. Metaboreflex-induced increases in left ventricular function were also depressed. These attenuated cardiac responses caused a smaller metaboreflex-induced rise in mean arterial pressure. We conclude that the ability of the muscle metaboreflex to elicit increases in cardiac function is impaired in hypertension, which may contribute to exercise intolerance.

Hypertrophied myocardium is vulnerable to ischemia/reperfusion injury and refractory to rapamycin-induced protection due to increased oxidative/nitrative stress

2018 ◽  
Vol 132 (1) ◽  
pp. 93-110 ◽  
Author(s):  
Lei-Lei Ma ◽  
Yang Li ◽  
Pei-Pei Yin ◽  
Fei-Juan Kong ◽  
Jun-Jie Guo ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Cardiac Function ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Pressure Overload ◽  
Left Ventricular ◽  
Cardiomyocyte Apoptosis ◽  
Coronary Artery Ligation ◽  
Nitrative Stress ◽  
Cardioprotective Effects

Left ventricular hypertrophy (LVH) is causally related to increased morbidity and mortality following acute myocardial infarction (AMI) via still unknown mechanisms. Although rapamycin exerts cardioprotective effects against myocardial ischemia/reperfusion (MI/R) injury in normal animals, whether rapamycin-elicited cardioprotection is altered in the presence of LVH has yet to be determined. Pressure overload induced cardiac hypertrophied mice and sham-operated controls were exposed to AMI by coronary artery ligation, and treated with vehicle or rapamycin 10 min before reperfusion. Rapamycin produced marked cardioprotection in normal control mice, whereas pressure overload induced cardiac hypertrophied mice manifested enhanced myocardial injury, and was refractory to rapamycin-elicited cardioprotection evidenced by augmented infarct size, aggravated cardiomyocyte apoptosis, and worsening cardiac function. Rapamycin alleviated MI/R injury via ERK-dependent antioxidative pathways in normal mice, whereas cardiac hypertrophied mice manifested markedly exacerbated oxidative/nitrative stress after MI/R evidenced by the increased iNOS/gp91phox expression, superoxide production, total NO metabolites, and nitrotyrosine content. Moreover, scavenging superoxide or peroxynitrite by selective gp91phox assembly inhibitor gp91ds-tat or ONOO− scavenger EUK134 markedly ameliorated MI/R injury, as shown by reduced myocardial oxidative/nitrative stress, alleviated myocardial infarction, hindered cardiomyocyte apoptosis, and improved cardiac function in aortic-banded mice. However, no additional cardioprotective effects were achieved when we combined rapamycin and gp91ds-tat or EUK134 in ischemic/reperfused hearts with or without LVH. These results suggest that cardiac hypertrophy attenuated rapamycin-induced cardioprotection by increasing oxidative/nitrative stress and scavenging superoxide/peroxynitrite protects the hypertrophied heart from MI/R.

Abstract 75: Ischemic Heart Failure is Exacerbated in CD39-null Mice

2015 ◽  
Vol 117 (suppl_1) ◽  
Author(s):  
Tatiana Novitskaya ◽  
Debra G Wheeler ◽  
Zhaobin Xu ◽  
Elena Chepurko ◽  
Bo Zhang ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Cardiac Function ◽  
Diastolic Pressure ◽  
Contractile Function ◽  
Ischemia Reperfusion ◽  
Smooth Muscles ◽  
Left Ventricular ◽  
Cardiac Performance ◽  
Coronary Artery Ligation ◽  
Genetic Ablation

Background: CD39 (ectonucleoside triphosphate diphosphohydrolase) is a nucleotidase expressed on endothelial cells, vascular smooth muscles cells, and leukocytes. CD39 plays a key role in vascular homeostasis, hydrolyzing extracellular ATP and ADP. CD39 has been shown to be important in models of ischemic preconditioning and cardiac ischemia reperfusion. However, the effect of CD39 activity on functional recovery of heart after myocardial infarction (MI) has not been evaluated. Hypothesis: Genetic ablation of CD39 expression exacerbates post-myocardial infarction cardiac function and fibrosis. Methods: Wild-type (WT) and CD39-null mice were subjected to coronary artery ligation. Cardiac function and protein evaluation of fibrotic markers was performed at day 28 post-MI. Results: Evaluation at Day 28 post-MI revealed that while mice of both genotypes had similarly reduced ejection fraction and equally compromised contractile function (dP/dtmax), there was a more pronounced negative effect on lusitropy (dP/dtmin) and increased left ventricular end-diastolic pressure in CD39-null mice. Therefore, cd39 gene ablation associates with the development of worsening cardiac performance. Histological analysis revealed increased collagen deposition and abundance of alpha-smooth muscle actin (αSMA) positive interstitial cells in the CD39-null hearts compared to WT hearts. To quantify these findings immunoblot analysis for collagen and αSMA was performed. We found that collagen and αSMA were increased at Day 28 post-MI, in CD39-null hearts compared to WT hearts. Conclusion: CD39 ablation has detrimental effects on post-MI recovery, resulting in diminished cardiac performance and increased fibrosis.

Abstract 16091: Cardioprotective Actions of the N-Terminal-Derived Annexin-A1 Peptide, Ac2-26, Against Myocardial Infarction in vivo

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Rebecca H Ritchie ◽  
Chengxue Qin ◽  
Renming Li ◽  
Jane E Bourke ◽  
Helen Kiriazis ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Coronary Artery ◽  
Troponin I ◽  
Ischemia Reperfusion ◽  
Left Ventricular ◽  
Western World ◽  
Lv Function ◽  
Coronary Artery Ligation ◽  
Annexin A1

Myocardial infarction (MI) is the major cause of heart failure and death in the Western world. Annexin-A1 is an endogenous, glucocorticoid-regulated anti-inflammatory protein. We have previously shown that this protein plays an important protective role in preserving left ventricular (LV) viability and function in vitro, actions that are reproduced by treatment with its N-terminal-derived peptide, Ac2-26. Little is known however about its cardioprotective actions in vivo, particularly beyond its early anti-necrotic actions in the first few hours of reperfusion. We now test the hypothesis that exogenous Ac2-26 limits multiple aspects of MI injury, over both the short and longer-term in vivo. In the first study, adult C57BL/6 mice were subjected to ischemia-reperfusion (left arterial descending coronary artery ligation, with 1-7 days reperfusion), and Ac2-26 was administered at 1mg/kg i.v. every 24h commencing 5mins before reperfusion. In the second study, mice were subjected to permanent coronary artery occlusion, with Ac2-26 administered 1mg/kg/day i.p. via osmotic pump inserted at time of surgery. As shown in the Table, Ac2-26 reduced cardiac necrosis after 24h reperfusion (infarct size, plasma troponin I levels), systemic and cardiac inflammation after 48h reperfusion (neutrophil and macrophage infiltration) and cardiac fibrosis after 7 days reperfusion. These protective actions at the level of cardiac morphology were associated with preservation of LV function 4wks after permanent occlusion, as determined on fractional shortening and velocity of circumferential fiber shortening. Taken together, our data is the first evidence of Ac2-26 cardioprotection beyond the first few hours of reperfusion in vivo, and importantly, the first to report Ac2-26-induced preservation of LV function in the heart post MI in vivo.

Regulation of phosphatase and tensin homolog on chromosome 10 in response to hypoxia

2012 ◽  
Vol 302 (9) ◽  
pp. H1806-H1817 ◽  
Author(s):  
Jinqiao Qian ◽  
Shukuan Ling ◽  
Alexander C. Castillo ◽  
Bo Long ◽  
Yochai Birnbaum ◽  
...  
Keyword(s):  
Coronary Artery ◽  
Infarct Size ◽  
Reperfusion Injury ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Left Ventricular ◽  
Coronary Artery Ligation ◽  
Chromosome 10 ◽  
Phosphatase And Tensin Homolog ◽  
Tensin Homolog

Phosphatase and tensin homolog on chromosome 10 (PTEN) is downregulated during hypertrophic and cancerous cell growth, leading to activation of the prosurvival Akt pathway. However, PTEN regulation in cardiac myocytes upon exposure to hypoxia remains unclear. We explored the role of PTEN in response to hypoxia/ischemia in the myocardium. We validated that PTEN is a transcriptional target of activating transcription factor 2 (ATF-2) and is positively regulated via a p38/ATF-2 signaling pathway. Accordingly, hypoxia-induced upregulation of phosphorylation of ATF-2 and PTEN were reversed by a dominant negative mutant p38. Inhibition of PTEN in cardiomyocytes attenuated hypoxia-induced cell death and apoptosis. Cardiac-specific knockout of PTEN resulted in increased phosphorylation of Akt and forkhead box O 1 (forkhead transcription factors), limited infarct size in animals exposed to ischemia-reperfusion injury, and ameliorated deterioration of left ventricular function and remodeling following permanent coronary artery occlusion. In addition, the activation of Bim, FASL, and caspase was coupled with PTEN activation, all of which were attenuated by PTEN inhibition. In conclusion, cardiomyocyte-specific conditional PTEN deletion limited myocardial infarct size in an in vivo model of ischemia-reperfusion injury and attenuated adverse remodeling in a model of chronic permanent coronary artery ligation.

Hyperinflation-induced cardiorespiratory failure in rats

2009 ◽  
Vol 107 (1) ◽  
pp. 275-282 ◽  
Author(s):  
Jeremy A. Simpson ◽  
Keith R. Brunt ◽  
Christine P. Collier ◽  
Steve Iscoe
Keyword(s):  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Lung Volume ◽  
Troponin T ◽  
Respiratory Acidosis ◽  
Left Ventricular ◽  
Cardiovascular Failure ◽  
Cardiorespiratory Failure ◽  
Arterial Hypoxemia ◽  
Ventricular Afterload

We previously showed that severe inspiratory resistive loads cause acute (<1 h) cardiorespiratory failure characterized by arterial hypotension, multifocal myocardial infarcts, and diaphragmatic fatigue. The mechanisms responsible for cardiovascular failure are unknown, but one factor may be the increased ventricular afterload caused by the large negative intrathoracic pressures generated when breathing against an inspiratory load. Because expiratory threshold loads increase intrathoracic pressure and decrease left ventricular afterload, we hypothesized that anesthetized rats forced to breathe against such a load would experience only diaphragmatic failure. Loading approximately doubled end-expiratory lung volume, halved respiratory frequency, and caused arterial hypoxemia and hypercapnia, respiratory acidosis, and increased inspiratory drive. Although hyperinflation immediately reduced the diaphragm's mechanical advantage, fatigue did not occur until near load termination. Mean arterial pressure progressively fell, becoming significant (cardiovascular failure) midway through loading despite tachycardia. Loading was terminated (endurance 125 ± 43 min; range 82–206 min) when mean arterial pressure dropped below 50 mmHg. Blood samples taken immediately after load termination revealed hypoglycemia, hyperkalemia, and cardiac troponin T, the last indicating myocardial injury that was, according to histology, mainly in the right ventricle. This damage probably reflects a combination of decreased O2 delivery (decreased venous return and arterial hypoxemia) and greater afterload due to hyperinflation-induced increase in pulmonary vascular resistance. Thus, in rats breathing at an increased end-expiratory lung volume, cardiorespiratory, not just respiratory, failure still occurred. Right heart injury and dysfunction may contribute to the increased morbidity and mortality associated with acute exacerbations of obstructive airway disease.

Abstract 402: Vitamin C Deficiency Impairs Cardiac Function and Post-infarction Survival in the Mouse

2017 ◽  
Vol 121 (suppl_1) ◽  
Author(s):  
Adolfo G Mauro ◽  
Donatas Kraskauskas ◽  
Bassem M Mohammed ◽  
Bernard J Fisher ◽  
Eleonora Mezzaroma ◽  
...  
Keyword(s):  
Vitamin C ◽  
Cardiac Function ◽  
Diastolic Function ◽  
Left Ventricular ◽  
Coronary Artery Ligation ◽  
Artery Ligation ◽  
Additional Group ◽  
Gulonolactone Oxidase ◽  
Low Levels ◽  
Systolic And Diastolic Function

Introduction: L-gulonolactone oxidase (Gulo) is the rate limiting enzyme for Vitamin C (VitC) biosynthesis. Humans rely on dietary VitC for collagen synthesis, extracellular matrix formation, and tissue regeneration. VitC deficiency is an unrecognized condition and its role in cardiac homeostasis and post-acute myocardial infarction (AMI) remodeling is unknown. Hypothesis: Low levels of VitC impair cardiac function and tissue repair following AMI. Methods: Adult male Gulo -/- knockout mice (C57BL6 background, N=8) and control C57BL (N=8), which are able to synthesize VitC were used. VitC deficiency was maintained supplying low levels of VitC (30mg/l) to Gulo -/- mice in drinking water. Mice underwent M-mode and Doppler echocardiography to measure left ventricular (LV) diameters and wall thicknesses, fractional shortening (FS), E and A waves, E/A ratio, isovolumetric relaxation time (IRT) and myocardial performance index (MPI). Experimental AMI was induced by coronary artery ligation for 7 days. An additional group of Gulo -/- were mice supplemented with physiological levels of VitC (330 mg/l) and underwent AMI. Results: VitC deficient Gulo -/- mice exhibited significantly reduced LV wall thicknesses, reduced FS, and impaired diastolic function, measured as significantly reduced E/A ratio and longer IRT (Panel A, B & C). Following AMI, 100% (8/8) of deficient Gulo -/- mice died within 5 days. Supplementation with physiological levels of VitC significantly improved survival after AMI (Panel D). Conclusion: VitC deficiency impairs systolic and diastolic function. Moreover, VitC is critical for the post-AMI survival.

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