Exercise Improves Heart Function after Myocardial Infarction: The Merits of AMPK.

BACKGROUND: AMPK is considered an important protein signaling pathway that has been shown to exert prominent cardioprotective effects on the pathophysiological mechanisms of numerous diseases. Following myocardial infarction, severe impairment of cardiac function occurs, leading to complications such as heart failure and arrhythmia. Therefore, protecting the heart and improving cardiac function are important therapeutic goals after myocardial infarction. Currently, there is substantial ongoing research on exercise-centered rehabilitation training, positioning exercise training as a significant nonpharmacological approach for preventing and treating numerous cardiovascular diseases. OBJECTIVE: Previous studies have reported that exercise can activate AMPK phosphorylation and upregulate the AMPK signaling pathway to play a cardioprotective role in coronary artery disease, but the specific mechanism involved remains to be elucidated. CONCLUSION: This review discusses the role and mechanism of the exercise-mediated AMPK pathway in improving postinfarction cardiac function through existing studies and describes the mechanism of exercise-induced myocardial repair of AMPK from multiple perspectives to formulate a reasonable and optimal exercise rehabilitation program for the prevention and treatment of myocardial infarction patients in the clinic.

A Retrospective Study of the No-Contact Technique to Obtain Radial Arteries for Coronary Artery Bypass Grafting.

BACKGROUND: To retrospectively study the experience with application of no-touch technique in radial artery (RA)-based coronary artery bypass grafting (CABG). METHODS: Clinical data of patients who underwent RA-based multi- (n = 45) or full-arterial CABG (n = 27) between January 2019 and June 2022 in the Affiliated Hospital of ZunYi Medical University were collected. The incidence of main cardiovascular events at 30-day follow-up, the antebrachial union condition and the vessel patency rate were analyzed. RESULTS: A total of 66 RAs were harvested and 70 RAs used as grafts. The number of RA used per patient was 1.46. Delayed antebrachial union occurred in 1 patient (1.45%). There was no death, cerebral infarction, myocardial infarction or revascularization at follow-up. Early coronary computed tomography (CT) after surgery revealed occlusion in 1 RA, with the patency rate being 98.57%. CONCLUSIONS: The No-touch RA harvesting technique, preservation and postoperative management applied in this study are effective and rational, and the application of RA as the graft in CABG is safe.

PDHA1 Alleviates Myocardial Ischemia-Reperfusion Injury by Improving Myocardial Insulin Resistance During Cardiopulmonary Bypass Surgery in Rats.

OBJECTIVE: Cardiopulmonary bypass (CPB) is a requisite technique for thoracotomy in advanced cardiovascular surgery. However, the consequent myocardial ischemia-reperfusion injury (MIRI) is the primary culprit behind cardiac dysfunction and fatal consequences post-operation. Prior research has posited that myocardial insulin resistance (IR) plays a vital role in exacerbating the progression of MIRI. Nonetheless, the exact mechanisms underlying this phenomenon remain obscure. METHODS: We constructed pyruvate dehydrogenase E1 α subunit (PDHA1) interference and overexpression rats and used ascending aorta occlusion in an in vivo model of CPB-MIRI. We devised an in vivo model of CPB-MIRI by constructing rat models with both pyruvate dehydrogenase E1α subunit (PDHA1) interference and overexpression through ascending aorta occlusion. We analyzed myocardial glucose metabolism and the degree of myocardial injury using functional monitoring, biochemical assays, and histological analysis. RESULTS: We discovered a clear downregulation of glucose transporter 4 (GLUT4) protein content expression in the CPB I/R model. In particular, cardiac-specific PDHA1 interference resulted in exacerbated cardiac dysfunction, significantly increased myocardial infarction area, more pronounced myocardial edema, and markedly increased cardiomyocyte apoptosis. Notably, the opposite effect was observed with PDHA1 overexpression, leading to a mitigated cardiac dysfunction and decreased incidence of myocardial infarction post-global ischemia. Mechanistically, PDHA1 plays a crucial role in regulating the protein content expression of GLUT4 on cardiomyocytes, thereby controlling the uptake and utilization of myocardial glucose, influencing the development of myocardial insulin resistance, and ultimately modulating MIRI. CONCLUSION: Overall, our study sheds new light on the pivotal role of PDHA1 in glucose metabolism and the development of myocardial insulin resistance. Our findings hold promising therapeutic potential for addressing the deleterious effects of MIRI in patients.

Primary pericardial mesothelioma complicated by pericardial calcification.

BACKGROUND: Pericardial calcification is usually a marker of chronic diseases, and its occurrence in rapidly progressing malignant primary pericardial mesothelioma (PPM) is extremely rare. Therefore, this atypical imaging appearance contributes to more frequent misdiagnosis of PPM. However, no systematic summary currently exists of the imaging characteristics of malignant pericardial calcification in PPM. In our report, its clinical characteristics are discussed in detail, to provide a reference to reduce the misdiagnosis rates of PPM. CASE PRESENTATION: A 50-year-old female patient was admitted to our hospital, presenting primarily with features suggestive of cardiac insufficiency. Chest computed tomography revealed significant pericardial thickening and localized calcification, suspicious of constrictive pericarditis. A chest examination performed through a midline incision showed a chronically inflamed and easily-ruptured pericardium that was closely adherent to the myocardium. Post-operative pathological examination confirmed a diagnosis of primary pericardial mesothelioma. Six weeks postoperatively, the patient experienced symptom recurrence and abandoned chemotherapy and radiation therapy. Nine months postoperatively, the patient died of heart failure. CONCLUSION: We report this case to highlight the rare finding of pericardial calcification in patients with primary pericardial mesothelioma. This case illustrated that confirmation of pericardial calcification cannot completely rule out rapidly developing PPM. Therefore, understanding the different radiological features of PPM can help to reduce its rate of early misdiagnosis.

Case report: Traumatic ventricular aneurysm combining tricuspid valve avulsion in a child: Diagnostic findings and treatment protocols.

This case report is an extremely rare case of a traumatic left ventricular aneurysm in a 3-year-old child who also had tricuspid valve avulsion due to blunt trauma. The diagnostic findings and treatment protocols are discussed to provide a clinical reference.

Dizziness Result From Anomalous Origin of Left Common Carotid Artery.

BACKGROUND: The anomalous origin of the left common carotid artery from the pulmonary artery is extremely scarce. At present, there are few relevant research and medical treatment data. This case is intended to provide relevant information and share treatment experiences. Case information: A 6-year-old child was diagnosed with patent ductus arteriosus and underwent surgery five years ago with occasional dizziness. After examination, it was found that the abnormality of her left common carotid artery originated from the pulmonary artery, and the patient underwent arterial ligation with the monitoring of cerebral oxygen consumption by near-infrared spectroscopy after careful preoperative evaluation. At present, it has been two years after the operation, and the patient is in good condition and has received regular follow-up. CONCLUSION: For patients with an abnormal left common carotid artery from the pulmonary artery, after careful preoperative evaluation such as cerebral angiography, under the monitoring of cerebral oxygen consumption by near-infrared spectroscopy, ligation of the proximal end of the artery of abnormal origin is safe and feasible.

Primary Osteosarcoma of Left Atrial Appendage in a Patient with Rheumatic Heart Disease.

Primary cardiac osteosarcoma is extremely rare, with all arising from the atrium, right ventricle, and cardiac valve, according to previous reports. We report a case of primary osteosarcoma of the left atrial appendage in a patient. We present a process of preoperative misdiagnosis, intraoperative confirmed diagnosis, and complete resection.

The Etiology and Molecular Mechanism Underlying Smooth Muscle Phenotype Switching in Intimal Hyperplasia of Vein Graft and the Regulatory Role of microRNAs.

Mounting evidence suggests that the phenotypic transformation of venous smooth muscle cells (SMCs) from differentiated (contractile) to dedifferentiated (proliferative and migratory) phenotypes causes excessive proliferation and further migration to the intima leading to intimal hyperplasia, which represents one of the key pathophysiological mechanisms of vein graft restenosis. In recent years, numerous miRNAs have been identified as specific phenotypic regulators of vascular SMCs (VSMCs), which play a vital role in intimal hyperplasia in vein grafts. The review sought to provide a comprehensive overview of the etiology of intimal hyperplasia, factors affecting the phenotypic transformation of VSMCs in vein graft, and molecular mechanisms of miRNAs involved in SMCs phenotypic modulation in intimal hyperplasia of vein graft reported in recent years.

miR-16-5p Is a Novel Mediator of Venous Smooth Muscle Phenotypic Switching.

Vein graft failure after coronary artery bypass grafting (CABG) is primarily caused by intimal hyperplasia, which results from the phenotypic switching of venous smooth muscle cells (SMCs). This study investigates the role and underlying mechanism of miR-16-5p in the phenotypic switching of venous SMCs. In rats, neointimal thickness and area increased over time within 28 days after CABG, as did the time-dependent miR-16-5p downregulation and SMC phenotypic switching. Platelet-derived growth factor-BB-induced miR-16-5p downregulation in HSVSMCs was accompanied by and substantially linked with alterations in phenotypic switching indicators. Furthermore, miR-16-5p overexpression increased SMCs differentiation marker expression while suppressing HSVSMCs proliferation and migration and drastically inhibiting neointimal development in vein grafts. The miR-16-5p inhibited zyxin expression, which was necessary for HSVSMCs phenotypic switching. The miR-16-5p/zyxin axis is a novel, potentially therapeutic target for preventing and treating venous graft intimal hyperplasia.

Cerebral infarction after cardiac surgery.

Cerebral infarction, a common central nervous system complication after adult cardiac surgery, is one of the main factors leading to the poor prognosis of cardiac surgery patients besides cardiac insufficiency. However, there is currently no effective treatment for cerebral infarction. Therefore, early prevention and diagnosis of postoperative cerebral infarction are particularly important. There are many factors and mechanisms during and after cardiac surgery that play an important role in the occurrence of postoperative cerebral infarction, such as intraoperative embolism, systemic inflammatory response syndrome, atrial fibrillation, temperature regulation, blood pressure control, use of postoperative blood products, and so forth. The mechanism by which most risk factors act on the human body, leading to postoperative cerebral infarction, is not well understood, and further research is needed. Therefore, this paper aims to summarize and explain the relevant risk factors, mechanisms, clinical signs, imaging characteristics, and early diagnosis methods of cerebral infarction complications after cardiac surgery, and provides useful data for the establishment of related diagnosis and treatment standards.

Transcatheter vs surgical aortic valve replacement in low to intermediate surgical risk aortic stenosis patients: A systematic review and meta-analysis of randomized controlled trials.

BACKGROUND: Transcatheter aortic valve replacement (TAVR) is regarded as the most superior alternative treatment approach for patients with aortic stenosis (AS) who are associated with high surgical risk, whereas the effectiveness of TAVR vs surgical aortic valve replacement (SAVR) in low to intermediate surgical risk patients remained inconclusive. This study aimed to determine the best treatment strategies for AS with low to intermediate surgical risk based on published randomized controlled trials (RCTs). HYPOTHESIS AND METHODS: RCTs that compared TAVR vs SAVR in AS patients with low to intermediate surgical risk were identified by PubMed, EmBase, and the Cochrane library from inception till April 2019. The pooled relative risks (RRs) with 95% confidence intervals (CIs) were calculated for the data collected using random-effects models. RESULTS: Seven RCTs with a total of 6929 AS patients were enrolled. We noted that TAVR significantly increased the risk of transient ischemic attack (TIA) (RR: 1.43; 95%CI: 1.04-1.96; P = .029), and permanent pacemaker implantation (RR: 3.00; 95%CI: 1.70-5.30; P < .001). However, TAVR was associated with lower risk of post-procedural bleeding (RR: 0.57; 95%CI: 0.33-0.98; P = .042), new-onset or worsening of atrial fibrillation (RR: 0.32; 95%CI: 0.23-0.45; P < .001), acute kidney injury (RR: 0.40; 95%CI: 0.25-0.63; P < .001), and cardiogenic shock (RR: 0.34; 95%CI: 0.19-0.59; P < .001). The risk of aortic-valve reintervention at 1- (RR: 2.63; 95%CI: 1.34-5.15; P = .005), and 2 years (RR: 3.19; 95%CI: 1.63-6.24; P = .001) in low to intermediate surgical risk patients who received TAVR was significantly increased than those who received SAVR. CONCLUSIONS: These findings indicated that low to intermediate surgical risk patients who received TAVR had low risk of complications, whereas the risk of TIA, permanent pacemaker implantation, and aortic-valve reintervention was increased.

Five-year results of a modified left atrial maze IV procedure in the treatment of atrial fibrillation: a randomized study.

BACKGROUND: The left atrial maze IV (LAM-IV) alone has been used to eliminate atrial fibrillation (AF) without severe right heart diseases. However, we felt that it could be improved and developed a modified LAM-IV (MLAM-IV). In this prospective trial, we aimed to investigate 5-year clinical outcomes of AF in patients treated by the novel MLAM-IV technique. METHODS: Between September 2012 and October 2013, 120 patients who underwent valve surgery and bipolar radiofrequency ablation for AF were randomized into the LAM-IV group (n = 60) or MLAM-IV group (n = 60). At postoperative follow-up examinations, data were recorded at 1, 3 and 6 months, and annually thereafter. RESULTS: The mean ablation time and postoperative ventilation time were shorter in the MLAM-IV group than in the LAM-IV group (P < 0.001 and P = 0.03, respectively). At 5 years, the rate of freedom from AF was 69.0% in the MLAM-IV group and 60.0% in the LAM-IV group (hazard ratio 0.71, 95% confidence interval 0.39 to 1.32, P = 0.42). There were no differences with respect to the early operative mortality and major complications, late mortality, and major adverse events. CONCLUSIONS: The MLAM-IV provides a technically simpler ablation process. The MLAM-IV was associated with less ventilation support in the early postoperative period. The long-term efficacy of the MLAM-IV in the treatment of AF is comparable to that of the LAM-IV.

The placental growth factor attenuates intimal hyperplasia in vein grafts by improving endothelial dysfunction.

Saphenous vein grafts (SVG) patency is limited by intimal hyperplasia (IH) caused by endothelial dysfunction. This study aimed to explore the effect of placental growth factor (PlGF) on the endothelial function of SVG. In rat models of external jugular vein-carotid artery graft treated with PlGF or saline hydrogel, PlGF inhibited vein graft IH (day 28: 12.0 ± 1.9 vs. 61.7 ± 13.1 µm, P < 0.001), promoted microvessel proliferation (day 14: 33.3% 3+ vs. 50.0% 2+, P = 0.03), and increased nitric oxide (NO) production (P < 0.05 on days 1/3/5) and NO synthase (NOS) expression by immunohistochemistry. In human umbilical vein endothelial cells (HUVECs) cultured under hypoxia and treated or not with PlGF, PlGF restored the survival (50 ng/ml PlGF, 48 h: 91.7 ± 0.6% vs. 84.9 ± 0.5%, P < 0.01), migration (by Matrigel assay), and tube formation ability (junctions, tubules, and tubule total length; all P < 0.01) of HUVECs after hypoxia. PlGF increased NO production through increased eNOS expression (P < 0.05), without changes in iNOS expression. The mRNA expression of eNOS decreased after the addition of the PI3K inhibitor LY294002 (P < 0.05). PlGF promoted the protein expression of eNOS by up-regulating AKT, and the AKT and eNOS protein levels were decreased after adding LY294002 (all P < 0.05). In conclusion, PlGF is a candidate for the inhibition of IH in SVG after coronary artery bypass graft. The effects of PlGF are mediated by the upregulation of the eNOS mRNA and protein through the PI3K/AKT signaling pathway. PlGF promotes the secretion of NO by endothelial cells and thereby reduces the occurrence and development of IH.

Successful recognition and percutaneous coronary intervention of delayed severe multiple coronary artery dissection caused by cardiac surgery: a case report.

BACKGROUND: Multiple coronary artery dissection is rare after cardiac surgery. It is difficult to recognize and is easily misdiagnosed as low output syndrome as a result of cardiopulmonary bypass (CPB). CASE PRESENTATION: A 43-year-old woman who had undergone cardiac surgery presented with unstable hemodynamics, and progressively increasing lactate, B-type natriuretic peptide, and cardiac enzyme levels, along with electrocardiogram (ECG) changes. Angiography indicated the presence of severe multiple coronary artery dissection, and 3 stents were implanted, which improved the patient's hemodynamic status and cardiac function. CONCLUSIONS: In the present report, we describe our experience with identifying and treating delayed severe multiple coronary artery dissection caused by cardiac surgery. Timely angiography is vital in patients suspected with coronary artery dissection, and percutaneous coronary intervention (PCI) should be considered as a treatment strategy for cases with severe multiple coronary artery dissection and unstable hemodynamics after cardiac surgery.

Role of Phosphorylated AMP-Activated Protein Kinase (AMPK) in Myocardial Insulin Resistance After Myocardial Ischemia-Reperfusion During Cardiopulmonary Bypass Surgery in Dogs.

BACKGROUND The aim of this study was to determine the role of AMP-activated protein kinase (AMPK) in myocardial insulin resistance after myocardial ischemia-reperfusion during cardiopulmonary bypass surgery in dogs. MATERIAL AND METHODS Twenty-four mongrel dogs were randomly assigned to 4 groups. The control group did not undergo aortic cross-clamping; the model group underwent 60 mins of aortic cross-clamping with 150 ml cardioplegic solution. The treatment group, the inhibition group respectively with 0.11mg/kg AICAR (AMPK agonist) in 150 ml cardioplegic solution and 0.11mg/kg Compound C (AMPK inhibitor) in 150 ml cardioplegic solution. The blood flow was determined and left ventricular myocardial tissue were taken at pre-bypass, 15, 60, and 90 min after aorta declamping, respectively. Expression of AMPK mRNA, p-AMPK and GLUT-4 proteins was determined by RT-PCR, IHC and WB. RESULTS Compared with the control group, receiving 60 min ischemia at 15 min after reperfusion, Myocardial Glucose Extraction Ratio were significantly decreased in the other 3 groups, it was significantly decreased from 20.0% to 1.2% at 60 min of reperfusion, and recovered to 6.1% after 90 min reperfusion in model group, while recovered to 4.1%, 12.0% after 90 min reperfusion respectively exposed to Compound C and AICAR. The expressions of p-AMPK, GLUT-4 protein and AMPK mRNA in myocardium were decreased in different experiment groups, but these changes occurred to a lesser extent in the treatment group. CONCLUSIONS The inability of GLUT-4 expression induced by the decreases in p-AMPK protein expression that may be one of the reasons for myocardial insulin resistance.

Effect of Si-RNA-silenced HIF-1α gene on myocardial ischemia-reperfusion-induced insulin resistance.

OBJECTIVE: To explore the effect (expression and implication) of hypoxia-inducible factor-1α (HIF-1α) silence induced by siRNA on the myocardial ischemia-reperfusion-induced insulin resistance in adult rats. METHODS: One-step enzymolysis method was used to isolate adult rat cardiomyocytes; adult rat cardiomyocytes were cultured; HIF-1α gene-specific Si-RNA was constructed and transfected into rat cardiomyocytes using liposome method. Myocardial IRI model was prepared. HIF-1α and glucose transporter 4 (GLUT-4) mRNA expression was detected by RT-PCR; distribution of GLUT-4 protein expression in adult rat cardiomyocytes was detected by immunofluorescence; Western blot was used for the detection of HIF-1α protein expression; isotope tracer assay was used to detect the changes in cell glucose (Glu) uptake rate. RESULTS: This method can stably get 85% to 90% active calcium tolerant adult rat cardiac myocytes, and the cultured cells were proved to be cardiomyocytes. After experiencing ischemia-reperfusion injury, HIF-1α mRNA expression levels in adult rat hypoxia cardiomyocytes had different degrees of increase compared with the control group (compared with the control group, P < 0.05). Compared with the model group, HIF-1α mRNA expression levels after ischemia and reperfusion in HIF-1αsi-RNA group and empty-vector group were lower than that in the control group and the model group; the expression reached the peak after 60 min of reperfusion, which did not change significantly in the control group. Expression of HIF-1α protein in myocardial cells was quite low in the control group; in the model group and intervention group, only after hypoxia-ischemia for 60 min, expression bands could be detected; especially in the model group, the expression had been increased until 60 min after reperfusion and began to decline from the time point of 180 min after reperfusion, but was still higher than that in the control group; in the intervention and empty-vector groups, it also increased rapidly at 60 min, but the expression was significantly lower than that in the model group; at 180 min after reperfusion, its protein expression peaked; while at 8 h after reperfusion, all the expression was extremely low. Compared with the control group, Glut4 mRNA expression in model group, transfected group and empty-vector group was reduced at the time points of T1-T4 (P < 0.05); the decline was the most significant at the time points of T1 and T2, followed by slightly increase at T3 and gradual recovery at T4; Compared with model group, Glut4 mRNA expression in transfection group was significantly reduced (P < 0.05); the decline was the most obvious at T1-T2, and then there was an increasing trend and it was recovered at T5 point. After experiencing ischemia, GLUT-4 protein expression changing trend was as follows: it was significantly reduced on the cell membrane, which was the most obvious from T1 to T3 and began to improve at T3, but still had not reached the level in the control group; it had been reached the levels of the control group at T5. After HIF-1αsi-RNA transfection and ischemia, GLUT-4 protein expression was increased in plasma and reduced on cell membrane; the decline was slightly improved at T3 and recovered to control distribution level at T5. After cardiac ischemia-reperfusion, glucose uptake rate decreased to varying degrees in myocardial cells and reached the lowest value after 60 min of ischemia, then gradually increased. After 8 h of reperfusion, the level in model group returned to the control level; compared with the model group, glucose concentration increased more serious in transfection group and empty-vector group after reperfusion. CONCLUSION: HIF-1α played a central regulatory role in this mechanism; HIF-1α may be one of the molecular mechanisms triggering myocardial IR.

Expression of metallothionein and Nrf2 pathway genes in lung cancer and cancer-surrounding tissues.

BACKGROUND: Nuclear factor (erythroid-derived 2)-like (Nrf)2 and metallothionein have been implicated in carcinogenesis. This study investigated the expression of Nrf2 and of Nrf2-targeted genes (NQO1 and GCLC) and the genes for the metallothionein (MT) isoforms (MT-1A and MT-2A) in human lung cancer and cancer-surrounding tissues. METHODS: Surgically removed lung cancer samples (n = 80) and cancer-surrounding tissues (n = 38) were collected from Zunyi Medical College Hospital, China. Total RNA was extracted, purified, and used for real-time reverse transcription-PCR analysis of interested genes. RESULTS: Expression of the Nrf2-targed genes NQO1 and GCLC tended to be higher (30 to 60%) in lung cancers, but was not significantly different from that in peri-cancer tissues. By contrast, expression of the genes for M)-1A, MT-2A, and the metal transcription factor MTF-1 were three-fold to four-fold lower in lung cancers. CONCLUSION: In surgical samples of lung cancer, MT expression was generally downregulated, whereas Nrf2 expression tended to be upregulated. These changes could play an integral role in lung carcinogenesis.

[Influence of siRNA-mediated PPARgamma gene knockdown on insulin resistance induced by myocardial ischemia-reperfusion in rats].

OBJECTIVE: To observe the influenece of siRNA-mediated PPARgamma gene knockdown on insulin resistance induced by myocardial ischemia-reperfusion in adult rats. METHOD: The targeting PPARgamma siRNA was synthesized. The myocardial cells of adult rats were isolated and cultured. They were divided into four groups: IRI group, siRNA-PPARgamma group, empty group and blank control group. Two groups of rat cardiac cells were transfected with PPARgamma-targeting siRNA (siRNA-PPARgamma group), or empty small interfering RNA (NC group), respectively. Real-time quantitive PCR was performed to detect the mRNA levels of PPARgamma and GLUT-4. PPARgamma protein expression level was determined with Western blot test. The uptake rate of glucose was determined by the isotope tracer method. RESULT: The PPARgamma mRNA and protein expression of IRI group were significantly higher than those in blank control group (P < 0.05). The PPARgamma mRNA and protein expression of siRNA-PPARgamma group were significantly less than those in blank control and IRI group (P < 0.01). There was no significant difference in the PPARgamma mRNA and protein expression between the blank group and IRI group. The mRNA expression of GLUT-4 in blank control was no significant difference at each time point. The mRNA expression of GLUT-4 in IRI group was significantly less at 0 min, but increased gradually over the following time point. Finally, The mRNA expression of GLUT-4 in IRI group restored the same level as blank control. There was no significant difference in the GLUT-4 mRNA expression between the empty group and IRI group. The GLUT-4 mRNA expression in siRNA-PPARgamma group was significantly less than that in IRI group or NC group (P < 0.05), and recovered more slowly than IRI group. After given insulin, The uptake rate of glucose in siRNA-PPARgamma group was significantly less at each time point compared with those in IRI group (P < 0.05), declined by 49.78%, 38.94%, 18.61%, 11.54% at 0 min, 15 min, 1 h, 2 h, respectively. At 6 h time point, the uptake rate of glucose in siRNA-PPARgamma group reached the same level as IRI group. There was no significant difference was observed in the uptake rate of glucose between the empty group and IRI group. CONCLUSION: The siRNA-mediated PPARgamma gene knockdown may enhance the myocardial insulin resistance. The molecular mechanisms that trigger myocardial cell insulin resistance might because the silence of PPARgamma expression decreasing the expression of GLUT-4 and decline its transportation from cytoplasm to membrane.