Sex differences in myocardial infarct size are abolished by sarcolemmal KATP channel blockade in rat

2006 ◽  
Vol 290 (6) ◽  
pp. H2644-H2647 ◽  
Author(s):  
Micah S. Johnson ◽  
Russell L. Moore ◽  
David A. Brown
Keyword(s):  
At Risk ◽  
Sex Differences ◽  
Infarct Size ◽  
Myocardial Infarct ◽  
Ischemia Reperfusion ◽  
Female Rats ◽  
Male Rats ◽  
Myocardial Infarct Size ◽  
Sprague Dawley

This study was conducted to examine the relationship between myocardial ATP-sensitive potassium (KATP) channels and sex differences in myocardial infarct size after in vitro ischemia-reperfusion (I/R). Hearts from adult male and female Sprague-Dawley rats were excised and exposed to an I/R protocol (1 h of ischemia, followed by 2 h of reperfusion) on a modified Langendorff apparatus. Hearts from female rats showed significantly smaller infarct sizes than hearts from males (23 ± 4 vs. 40 ± 5% of the zone at risk, respectively; P < 0.05). Administration of HMR-1098, a sarcolemmal KATP channel blocker, abolished the sex difference in infarct size (42 ± 4 vs. 45 ± 5% of the zone at risk in hearts from female and male rats, respectively; P = not significant). Further experiments showed that blocking the KATP channels in ischemia, and not reperfusion, was sufficient to increase infarct size in female rats. These data demonstrate that sarcolemmal KATP channels are centrally involved in mechanisms that underlie sex differences in the susceptibility of the intact heart to I/R injury.

Abstract 300: Topical Application of IcyHot Reduces Myocardial Infarct Size in Rodents by a TRPA1-dependent Mechanism

2017 ◽  
Vol 121 (suppl_1) ◽  
Author(s):  
Yun Wu ◽  
Yao Lu ◽  
Eric R Gross
Keyword(s):  
Infarct Size ◽  
Transient Receptor Potential ◽  
Ischemia Reperfusion Injury ◽  
Calcium Influx ◽  
Myocardial Infarct ◽  
Ischemia Reperfusion ◽  
Myocardial Infarct Size ◽  
Sprague Dawley ◽  
Area At Risk ◽  
Reactive Aldehydes

Toxic reactive aldehydes are formed during ischemia-reperfusion. The ion channel transient receptor potential ankryin 1 (TRPA1) is irreversibly modified by reactive aldehydes which can cause calcium influx and cell death. Here we tested whether topically applied creams containing a reversible TRPA1 agonist could reduce myocardial infarct size. Male Sprague-Dawley rats 8-10 weeks age were subjected to an in vivo myocardial ischemia-reperfusion model of 30 minutes of left anterior descending (LAD) coronary artery ischemia followed by 2 hours reperfusion. Prior to ischemia, rats were untreated or had 1g of cream applied to the abdomen. The creams tested were IcyHot, Bengay, Tiger Balm, or preparation H (Fig. 1A). Hearts were negatively stained for the area at risk and the infarct size was determined by using TTC staining (Fig. 1B). A subset of rodents prior to receiving IcyHot also received an intravenous bolus of the TRPA1 antagonist TCS-5861528 (1mg/kg) or AP-18 (1mg/kg). Interestingly, both IcyHot and Bengay reduced myocardial infarct size compared to untreated rodents (Fig. 1C and 1D IcyHot: 41±3%*, Bengay: 50±2%* versus control 62±1%, n=6/group, *P<0.001). Both preparation H and Tiger Balm failed to reduce myocardial infarct size (Tiger Balm: 63±2%, preparation H 59±2%). Giving a TRPA1 antagonist prior to IcyHot also blocked the reduction in infarct size. Our additional data also indicates the methyl salicylate (mint) in IcyHot and Bengay is the agent that limits myocardial infarct size. Since IcyHot and Bengay are safely used by humans, targeting TRPA1 by using products such as these could be quickly translatable and widely used to reduce ischemia-reperfusion injury.

scholarly journals Nod-like Receptor Protein 3 (Nlrp3) Inflammasomes Inhibition by Metformin Limits Myocardial Ischemia/reperfusion Injury

2020 ◽  
Author(s):  
Jing Zhang ◽  
Liu Yang ◽  
Qin Zhang ◽  
Xing Shi ◽  
Fuzhou Hua ◽  
...  
Keyword(s):  
Infarct Size ◽  
Nlrp3 Inflammasome ◽  
Myocardial Infarct ◽  
Ischemia Reperfusion ◽  
Inflammasome Activation ◽  
Myocardial Infarct Size ◽  
Ampk Phosphorylation ◽  
Nlrp3 Inflammasome Activation ◽  
Cardioprotective Effects

Abstract Background Ischemia/reperfusion (I/R) injury is a life-threatening vascular emergency following myocardial infarction. Our previous study showed cardioprotective effects of metformin against myocardial I/R injury. In this study, we further examined the involvement of AMPK mediated activation of NLRP3 inflammasome in this cardioprotective effect of metformin. Methods Myocardial I/R injury was simulated in a rat heart Langendorff model and neonatal rat ventricle myocytes (NRVMs) were subjected to hypoxi/reoxygenation (H/R) to establish an in vitro model. Outcome measures included myocardial infarct size, hemodynamic monitoring, myocardial tissue injury, myocardial apoptotic index and the inflammatory response. myocardial infarct size and cardiac enzyme activities. Results First, we found that metformin postconditioning can not only significantly alleviated myocardial infarct size, attenuated cell apoptosis, and inhibited myocardial fibrosis. Furthermore, metformin activated phosphorylated AMPK, decreased pro-inflammatory cytokines, TNF-α, IL-6 and IL-1β, and decreased NLRP3 inflammasome activation. In isolated NRVMs metformin increased cellular viability, decreased LDH activity and inhibited cellular apoptosis and inflammation. Importantly, inhibition of AMPK phosphorylation by Compound C (CC) resulted in decreased survival of cardiomyocytes mainly by inducing the release of inflammatory cytokines and increasing NLRP3 inflammasome activation. Finally, in vitro studies revealed that the NLRP3 activator nigericin abolished the anti-inflammatory effects of metformin in NRVMs, but it had little effect on AMPK phosphorylation. Conclusions Collectively, our study confirmed that metformin exerts cardioprotective effects by regulating myocardial I/R injury-induced inflammatory response, which was largely dependent on the enhancement of the AMPK pathway, thereby suppressing NLRP3 inflammasome activation.

scholarly journals Therapeutic Effect of Local Injection of VX765 Sodium Alginate Nanogel on Myocardial Infarction

2021 ◽  
Author(s):  
Qingxin Tian ◽  
Jianlong Liu ◽  
Qin Chen ◽  
Mingxiao Zhang
Keyword(s):  
Myocardial Infarction ◽  
Cardiac Function ◽  
Infarct Size ◽  
Sodium Alginate ◽  
Cardiac Fibrosis ◽  
Myocardial Infarct ◽  
Morphological Observation ◽  
Myocardial Infarct Size ◽  
Sprague Dawley

Abstract Objectives: To determine the effect of polyethyleneimine/sodium alginate composite nano-gel (AG/PEI-VX765NGs) coated with VX765 on cardiac function in rats with myocardial infarction (MI). Methods: VX765-polyethyleneimine nano-microspheres (PEI-VX765 NP) were encapsulated by sodium alginate (AG) nanogel (NGs) to construct AG/PEI-VX765 NGs. The morphological observation was performed under scanning electron microscope (SEM). The viability was evaluated by using CCK-8 assay in vitro. Then, 24 male SPF Sprague-Dawley rats were randomly divided into 4 groups: Sham, MI, PEI-VX765NP, and AG/PEI-VX765NGs. After 28 days, rats in each group were subjected to assessment of cardiac function by echocardiography. The myocardial infarct size was evaluated by TTC test, and the differences in cardiac fibrosis and cardiomyocyte apoptosis between groups were analyzed by histological methods. Results: The prepared NGs shows a porous structure, while PEI-VX765 NP is uniformly distributed in the AG NGs samples. AG/PEI-VX765 NGs with a concentration of VX765 (range: 0-1000 μM) displayed no significant toxicity to cells. Meanwhile, we observed a relatively more persistent release of VX765 from AG/PEI-VX765 NGs compared with PEI-VX765. LVIDs and LVIDd in both PEI-VX765 and AG/PEI-VX765NGs groups were significantly smaller than those in MI group, while ejection fraction (EF) and short-axis shortening rate (FS) were markedly increased in the above-mentioned two groups. Compared with MI group, PEI-VX765 and AG/PEI-VX765NGs groups exhibited a significant reduction in the infarct size, degree of fibrosis, and the rate of TUNEL positive cells. Conclusion: AG/PEI-VX765NGs can significantly improve the cardiac function of rats with MI.

Nogo-A mediated endoplasmic reticulum stress during myocardial ischemic-reperfusion injury in diabetic rats

2021 ◽  
Author(s):  
yonghong xiong ◽  
yan leng ◽  
wei li ◽  
wenyuan li ◽  
rong chen ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Er Stress ◽  
Molecular Mechanisms ◽  
Myocardial Infarct ◽  
Ischemia Reperfusion ◽  
Myocardial Damage ◽  
Diabetic Rats ◽  
Myocardial Infarct Size ◽  
Sprague Dawley

Abstract Background: Diabetic myocardial ischemia reperfusion (MI/R) injury is aggravated after myocardial infarction, which leads to myocardial damage. Molecular mechanisms associated with the diabetic ischemia-related cardiac diseases are not yet fully understood. Nogo-A is an endoplasmic reticulum (ER) protein ubiquitously expressed in tissues including in the heart. However, the mechanisms that account for the Nogo-A in MI/R injury remain unknown. Methods: SD (Sprague Dawley) rats were subjected to 45 min of ischemia, followed by 3 h reperfusion. Rats were injection with streptozotocin (60mg/kg), tauroursodeoxycholic acid injection (100mg/kg) or corresponding controls just prior to MI/R. Blood and heart samples were collected at 3 h post-reperfusion. Serum LDH and CK-MB, myocardial infarct size, histopathologic changes, apotosis and ER stress were analyzed to evaluate MI/R injury. Signaling pathways were also investigated in vitro using embryonic rat cardiomyocyte-derived H9c2 cells cultures to identify underlying mechanisms for Nogo-A in diabetic MI/R injury. Results: TUDCA treatment significantly reduced Nogo-A, GRP78 and CHOP levels, diminished myocardial infarct areas, attenuated ER stress and decreased myocardial apoptosis after MI/R. ER stress signaling was significantly decreased in the TUDCA-treated MI/R group compared with controls. The effect of Nogo-A was abrogated by pretreatment with knockdown CHOP. A positive feedback loop between Nogo-A and CHOP was found leading to an enhanced ER stress in diabetic MI/R injure. Conclusions: Our data suggest that Nogo-A mediated ER stress plays a major role in diabetic MI/R injury and Nogo-A might be a key regulator of ER stress.

scholarly journals Luteolin Modulates SERCA2a Leading to Attenuation of Myocardial Ischemia/ Reperfusion Injury via Sumoylation at Lysine 585 in Mice

2018 ◽  
Vol 45 (3) ◽  
pp. 883-898 ◽  
Author(s):  
Yinping Du ◽  
Ping Liu ◽  
Tongda Xu ◽  
Defeng Pan ◽  
Hong Zhu ◽  
...  
Keyword(s):  
Myocardial Ischemia ◽  
Infarct Size ◽  
Ischemia Reperfusion Injury ◽  
Heart Function ◽  
Myocardial Infarct ◽  
Ischemia Reperfusion ◽  
Myocardial Infarct Size ◽  
Myocardial Ischemia Reperfusion

Background/Aims: The myocardial sarcoplasmic reticulum calcium ATPase (SERCA2a) is a pivotal pump responsible for calcium cycling in cardiomyocytes. The present study investigated the effect of luteolin (Lut) on restoring SERCA2a protein level and stability reduced by myocardial ischemia/reperfusion (I/R) injury. We verified a hypothesis that Lut protected against myocardial I/R injury by regulating SERCA2a SUMOylation. Methods: The hemodynamic data, myocardial infarct size of intact hearts, apoptotic analysis, mitochondrial membrane potential (ΔΨm), the level of SERCA2a SUMOylation, and the activity and expression of SERCA2a were examined in vivo and in vitro to clarify the cardioprotective effects of Lut after SUMO1 was knocked down or over-expressed. The putative SUMO conjugation sites in mouse SERCA2a were investigated as the possible regulatory mechanism of Lut. Results: Initially, we found that Lut reversed the SUMOylation and stability of SERCA2a as well as the expression of SUMO1, which were reduced by I/R injury in vitro. Furthermore, Lut increased the expression and activity of SERCA2a partly through SUMO1, thus improving ΔΨm and reducing apoptotic cells in vitro and promoting the recovery of heart function and reducing infarct size in vivo. We also demonstrated that SUMO acceptor sites in mouse SERCA2a involving lysine 585, 480 and 571. Among the three acceptor sites, Lut enhanced SERCA2a stability via lysine 585. Conclusions: Our results suggest that Lut regulates SERCA2a through SUMOylation at lysine 585 to attenuate myocardial I/R injury.

scholarly journals EFFECTS OF EXERCISE COMBINED WITH APELIN-13 ON CARDIAC FUNCTION IN THE ISOLATED RAT HEART

2018 ◽  
Vol 24 (4) ◽  
pp. 273-279
Author(s):  
Afshin Nazari ◽  
Khadige Zahabi ◽  
Yaser Azizi ◽  
Maryam Moghimian
Keyword(s):  
Exercise Training ◽  
Cardiac Function ◽  
Infarct Size ◽  
Myocardial Infarct ◽  
Ischemia Reperfusion ◽  
Combined Treatment ◽  
Left Ventricular ◽  
Male Rats ◽  
Myocardial Infarct Size ◽  
Creatine Kinase Mb

ABSTRACT Exercise and apelin have been shown to increase cardiac function and elicit tolerance to ischemia/reperfusion (IR) injuries. This study aimed at determining whether the combination of exercise training and apelin pretreatment could integrate the protective effects of each of them in the heart against IR injury. Male rats were divided into four experimental groups: 1: Rats with ischemia/reperfusion (IR), 2: subjected to exercise training for 8 weeks (EX+IR), 3: apelin-13 (10 nmol/kg/day) for 7 days (Apel+IR) in the last week of training, and 4: exercise training plus apelin-13 (EX+Apel+IR). Isolated hearts were perfused using the Langendorff method and subjected to 30 min of regional ischemia followed by 60 min of reperfusion. Treadmill exercise training was conducted for 8 weeks. Hemodynamic parameters were recorded throughout the experiment. Ischemia-induced arrhythmias, myocardial infarct size (IS), creatine kinase-MB (CK-MB) isoenzyme and plasma lactate dehydrogenase (LDH) activity was measured in all animals. Administration of apelin-13 plus exercise increased left ventricular developed pressure (LVDP) at the end of ischemia and reperfusion compared with other groups. After 30 min of ischemia, dP/dtmax was higher in EX+Apel+IR than in Apel+IR and EX+IR groups. During 30 min ischemia, exercise training, apelin-13 and combined treatment produced a significant reduction in the numbers of premature ventricular complexes. A combination of exercise and apelin-13 also reduced infarct size, CK-MB, LDH and severity of arrhythmia. These results suggest that combined therapies with apelin-13 and exercise training may integrate the beneficial effects of each of them alone on cardiac contractility, arrhythmia and limiting of infarct size. Level of evidence I; Therapeutic Studies - Investigating the Results of Treatment.

scholarly journals Melatonin postconditioning combined with sitagliptin exerts full cardioprotection in diabetic hearts of aged rats through an AMPK-dependent mechanism

2021 ◽  
Vol 73 (1) ◽  
pp. 83-92
Author(s):  
Ronggang Song ◽  
Jing Ren ◽  
Junxia Sun ◽  
Ming Li
Keyword(s):  
Infarct Size ◽  
Myocardial Infarct ◽  
Ischemia Reperfusion ◽  
Diabetic Rats ◽  
Myocardial Infarct Size ◽  
Aged Rats ◽  
Sprague Dawley ◽  
Oxidative Markers ◽  
Mitochondrial Superoxide ◽  
Compound C

The presence of multiple comorbidities in patients facing myocardial ischemia-reperfusion (IR) injury is the main obstacle for cardioprotection. This study investigated the effect of melatonin postconditioning combined with sitagliptin pretreatment on cardioprotection in diabetic aged rats by evaluating oxidative stress, apoptosis and involvement of the AMPK/SIRT1 pathway. The type-2 high-fat/streptozotocin experimental model in aged Sprague-Dawley rats (n=78) was used. The animals underwent left coronary occlusion for 30 min, followed by 3 h reperfusion. Diabetic rats were pretreated with sitagliptin (20 mg/kg, i.p.) and received melatonin (10 mg/kg, i.p.) early in reperfusion. Myocardial infarct size, histological changes, oxidative markers, mitochondrial reactive oxygen species (mitoROS) and expression of proteins regulating apoptosis and AMPK/SIRT1 activity were measured. The infarct size-sparing effect of the combination of melatonin plus sitagliptin was greater than that observed in individual treatments (P<0.01). Combination therapy significantly reduced IRinduced elevation of 8-isoprostane, mitoROS and proapoptotic proteins Bax and cleaved caspase-3, and increased IR-induced downregulation of mitochondrial superoxide-dismutase, glutathione, anti-apoptotic protein Bcl2, phosphorylated AMPK and SIRT1 (P<0.01, P<0.001). Inhibition of AMPK via compound-C completely reversed combination-induced cardioprotection. Thus, improving cardiac antioxidative and antiapoptotic responses via upregulation of AMPK/SIRT1 activity may represent a central mechanism through which melatonin plus sitagliptin attenuate myocardial IR injury in diabetic-aged rats.

scholarly journals Overexpression of SERCA2a Alleviates Cardiac Microvascular Ischemic Injury by Suppressing Mfn2-Mediated ER/Mitochondrial Calcium Tethering

2021 ◽  
Vol 9 ◽  
Author(s):  
Feng Tian ◽  
Ying Zhang
Keyword(s):  
Endoplasmic Reticulum ◽  
Infarct Size ◽  
Myocardial Infarct ◽  
Ischemic Injury ◽  
Calcium Overload ◽  
Mitochondrial Calcium ◽  
Myocardial Infarct Size ◽  
Hypoxic Injury

Our previous research has shown that type-2a Sarco/endoplasmic reticulum Ca2+-ATPase (SERCA2a) undergoes posttranscriptional oxidative modifications in cardiac microvascular endothelial cells (CMECs) in the context of excessive cardiac oxidative injury. However, whether SERCA2a inactivity induces cytosolic Ca2+ imbalance in mitochondrial homeostasis is far from clear. Mitofusin2 (Mfn2) is well known as an important protein involved in endoplasmic reticulum (ER)/mitochondrial Ca2+ tethering and the regulation of mitochondrial quality. Therefore, the aim of our study was to elucidate the specific mechanism of SERCA2a-mediated Ca2+ overload in the mitochondria via Mfn2 tethering and the survival rate of the heart under conditions of cardiac microvascular ischemic injury. In vitro, CMECs extracted from mice were subjected to 6 h of hypoxic injury to mimic ischemic heart injury. C57-WT and Mfn2KO mice were subjected to a 1 h ischemia procedure via ligation of the left anterior descending branch to establish an in vivo cardiac ischemic injury model. TTC staining, immunohistochemistry and echocardiography were used to assess the myocardial infarct size, microvascular damage, and heart function. In vitro, ischemic injury induced irreversible oxidative modification of SERCA2a, including sulfonylation at cysteine 674 and nitration at tyrosine 294/295, and inactivation of SERCA2a, which initiated calcium overload. In addition, ischemic injury-triggered [Ca2+]c overload and subsequent [Ca2+]m overload led to mPTP opening and ΔΨm dissipation compared with the control. Furthermore, ablation of Mfn2 alleviated SERCA2a-induced mitochondrial calcium overload and subsequent mito-apoptosis in the context of CMEC hypoxic injury. In vivo, compared with that in wild-type mice, the myocardial infarct size in Mfn2KO mice was significantly decreased. In addition, the findings revealed that Mfn2KO mice had better heart contractile function, decreased myocardial infarction indicators, and improved mitochondrial morphology. Taken together, the results of our study suggested that SERCA2a-dependent [Ca2+]c overload led to mitochondrial dysfunction and activation of Mfn2-mediated [Ca2+]m overload. Overexpression of SERCA2a or ablation of Mfn2 expression mitigated mitochondrial morphological and functional damage by modifying the SERCA2a/Ca2+-Mfn2 pathway. Overall, these pathways are promising therapeutic targets for acute cardiac microvascular ischemic injury.

Abstract 2894: Essential Role of ERK 1/2 in Sildenafil-Induced Early and Delayed Cardioprotection in Mice

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Anindita das ◽  
Lei Xi ◽  
Fadi N Salloum ◽  
Yuan J Rao ◽  
Rakesh C Kukreja
Keyword(s):  
South Carolina ◽  
Infarct Size ◽  
Myocardial Infarct ◽  
Ischemia Reperfusion ◽  
Critical Role ◽  
Heart Association ◽  
Myocardial Infarct Size ◽  
Western Blots ◽  
Delayed Cardioprotection

Background: Sildenafil (SIL), a potent inhibitor of phosphodiesterase-5 induces powerful protection against myocardial ischemia-reperfusion (I-R) injury through activation of protein kinase G (PKG). However, the downstream targets of PKG in SIL-induced cardioprotection remain unclear. We hypothesized that PKG-dependent activation of survival kinase, ERK may play a critical role in SIL-induced cardioprotection in mice. Methods & Results: Ventricular myocytes were isolated from adult male ICR mice and exposed to 40 min of simulated ischemia (SI) with/without 1 hr pre-incubation of SIL (1 μM). Myocyte necrosis and apoptosis were determined after 1 hr or 18 hrs of reoxygenation (RO) using trypan blue or TUNEL assay, respectively. Pretreatment with SIL protected cardiomyocytes after SI-RO (necrosis 18.5±0.5% and apoptosis 6.6±0.7%; n=4, p<0.001) as compared with controls (necrosis 42.1±1.8% and apoptosis 23.3±0.9%). Co-incubation of PD98059 (20 μM), a selective ERK1/2 inhibitor blocked both anti-necrotic and anti-apoptotic protection in cardiomyocytes. Furthermore, intra-coronary infusion of SIL (1 μM) in Langendorff isolated mouse hearts 10 min prior to zero-flow global I (20 min) and R (30 min) significantly reduced myocardial infarct size (from 29.4±2.4% to 16.0±3.0%; p<0.05, n=6). Co-treatment of PD98059 abrogated SIL-induced protection (33.0±5.9; n=4). To evaluate the role of ERK1/2 in delayed cardioprotection, mice were treated with saline or SIL (0.7 mg/kg i.p.) 24 hours before global I-R in Langendorff mode. PD98059 (1 mg/kg) was administered (i.p.) 30 min before the treatment of SIL. Infarct size was reduced from 27.6±3.3% in saline-treated controls to 6.9±1.2% in SIL-treated mice (P<0.05, n=6). The delayed protective effect of SIL was also abolished by PD98059 (22.5±2.3%). Western Blots revealed that SIL significantly increased phosphorylation of ERK1/2 which was blocked by PKG inhibitor, KT5823 in the heart and adult myocytes. Selective knockdown of PKG in cardiomyocytes with short hairpin RNA of PKG also blocked the phosphorylation of ERK1/2. Conclusion: SIL-induced cardioprotection involves the activation and phosphorylation of ERK which appear to be intimately linked with a PKG-dependent survival pathway. This research has received full or partial funding support from the American Heart Association, AHA Mid-Atlantic Affiliate (Maryland, North Carolina, South Carolina, Virginia & Washington, DC).

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