Medicine and Health Sciences Commons^™

Endothelial Cell-Derived Microparticles From Patients With Obstructive Sleep Apnea Hypoxia Syndrome And Coronary Artery Disease Increase Aortic Endothelial Cell Dysfunction., Lixin Jia, Jingyao Fan, Wei Cui, Sa Liu, Na Li, Wayne Bond Lau, Xin-Liang Ma, Jie Du, Shaoping Nie, Yongxiang Wei

Department of Emergency Medicine Faculty Papers

BACKGROUND/AIMS: Obstructive sleep apnea hypoxia syndrome (OSAHS) is an independent risk factor for coronary artery disease (CAD). Treatment of OSAHS improves clinical outcome in some CAD patients, but the relationship between OSAHS and CAD is complex. Microparticles (MPs) are shed by the plasma membrane by either physiologic or pathologic stimulation. In the current study, we investigated the role of MPs in the context of OSAHS.

METHODS AND RESULTS: 54 patients with both suspected coronary artery stenosis and OSAHS were recruited and underwent both coronary arteriography and polysomnography. Circulating MPs were isolated and analyzed by flow cytometry. CAD+OSAHS patients exhibited greater …

Adiponectin Partially Rescues High Glucose/High Fat-Induced Impairment Of Mitochondrial Biogenesis And Function In A Pgc-1Α Dependent Manner., H. Wang, W.-J. Yan, J.-L. Zhang, F.-Y. Zhang, C. Gao, Y.-J. Wang, W.B. Lau, L. Tao

Department of Emergency Medicine Faculty Papers

OBJECTIVE: Plasma adiponectin (APN) levels are decreased in diabetic patients. Dysfunctional mitochondrial biogenesis is involved in type 2 diabetes (T2DM) pathogenesis, by unclear mechanisms. The present study determined (1) whether myocardial mitochondrial biogenesis was impaired in cardiomyocytes exposed to a high glucose/high fat (HGHF) medium (a T2DM in vitro model), (2) the effects of APN administration upon mitochondrial biogenesis in cardiomyocytes affected by HGHF incubation, and 3) the involved underlying mechanisms.

MATERIALS AND METHODS: Neonatal rat ventricular myocytes (NRVMs) were isolated and incubated in HGHF medium. Mitochondrial function was assessed by ATP content, and fluorescent microscopic analysis of myocardial apoptosis …

Advanced Glycation End Products Accelerate Ischemia/Reperfusion Injury Through Receptor Of Advanced End Product/Nitrative Thioredoxin Inactivation In Cardiac Microvascular Endothelial Cells., Yi Liu, Yanzhuo Ma, Rutao Wang, Chenhai Xia, Rongqing Zhang, Kun Lian, Ronghua Luan, Lu Sun, Lu Yang, Wayne B Lau, Haichang Wang, Ling Tao

Department of Emergency Medicine Faculty Papers

The advanced glycation end products (AGEs) are associated with increased cardiac endothelial injury. However, no causative link has been established between increased AGEs and enhanced endothelial injury after ischemia/reperfusion. More importantly, the molecular mechanisms by which AGEs may increase endothelial injury remain unknown. Adult rat cardiac microvascular endothelial cells (CMECs) were isolated and incubated with AGE-modified bovine serum albumin (BSA) or BSA. After AGE-BSA or BSA preculture, CMECs were subjected to simulated ischemia (SI)/reperfusion (R). AGE-BSA increased SI/R injury as evidenced by enhanced lactate dehydrogenase release and caspase-3 activity. Moreover, AGE-BSA significantly increased SI/R-induced oxidative/nitrative stress in CMECs (as measured …

Methylglyoxal Increases Cardiomyocyte Ischemia-Reperfusion Injury Via Glycative Inhibition Of Thioredoxin Activity., Xiaoliang Wang, Wayne B. Lau, Yue-Xing Yuan, Ya-Jing Wang, Wei Yi, Theodore A. Christopher, Bernard L. Lopez, Hui-Rong Liu, Xin-Liang Ma

Department of Emergency Medicine Faculty Papers

Diabetes mellitus (DM) is closely related to cardiovascular morbidity and mortality, but the specific molecular basis linking DM with increased vulnerability to cardiovascular injury remains incompletely understood. Methylglyoxal (MG), a precursor to advanced glycation end products (AGEs), is increased in diabetic patient plasma, but its role in diabetic cardiovascular complications is unclear. Thioredoxin (Trx), a cytoprotective molecule with antiapoptotic function, has been demonstrated to be vulnerable to glycative inhibition, but whether Trx is glycatively inhibited by MG, thus contributing to increased cardiac injury, has never been investigated. Cultured H9c2 cardiomyocytes were treated with MG (200 muM) for 6 days. The …

Cardiomyocyte-Derived Adiponectin Is Biologically Active In Protecting Against Myocardial Ischemia-Reperfusion Injury., Yajing Wang, Wayne Bond Lau, Erhe Gao, Ling Tao, Yuexing Yuan, Rong Li, Xiaoliang Wang, Walter J. Koch, Xin-Liang Ma

Department of Emergency Medicine Faculty Papers

Adiponectin (APN) has traditionally been viewed as an adipocyte-specific endocrine molecule with cardioprotective effects. Recent studies suggest that APN is also expressed in cardiomyocytes. However, biological significances of this locally produced APN remain completely unknown. The aim of this study was to investigate the pathological and pharmacological significance of cardiac-derived APN in cardiomyocyte pathology. Adult cardiomyocytes from wild-type littermates (WT) or gene-deficient mice were pretreated with vehicle (V) or rosiglitazone (RSG) for 6 h followed by simulated ischemia-reperfusion (SI/R, 3 h/12 h). Compared with WT cardiomyocytes, myocytes from APN knockout (APN-KO) mice sustained greater SI/R injury, evidenced by greater oxidative/nitrative …

Cardioprotective Effect Of Adiponectin Is Partially Mediated By Its Ampk-Independent Antinitrative Action., Yajing Wang, Ling Tao, Yuexing Yuan, Wayne Bond Lau, Rong Li, Bernard L. Lopez, Theodore A. Christopher, Rong Tian, Xin-Liang Ma

Department of Emergency Medicine Faculty Papers

Adiponectin (APN) exerts its metabolic regulation largely through AMP-dependent protein kinase (AMPK). However, the role of AMPK in APN's antiapoptotic effect in ischemic-reperfused (I/R) adult cardiomyocytes remains incompletely understood. The present study was designed to determine the involvement of AMPK in the antiapoptotic signaling of APN. Cardiomyocytes from adult male mice overexpressing a dominant-negative alpha(2)-subunit of AMPK (AMPK-DN) or wild-type (WT) littermates were subjected to simulated I/R (SI/R) and pretreated with 2 microg/ml globular domain of APN (gAPN) or vehicle. SI/R-induced cardiomyocyte apoptosis was modestly increased in AMPK-DN cardiomyocytes (P < 0.05). Treatment with gAPN significantly reduced SI/R-induced apoptosis in WT cardiomyocytes as well as in AMPK-DN cardiomyocytes, indicating that the antiapoptotic effect of gAPN is partially AMPK independent. Furthermore, gAPN-induced endothelial nitric oxide synthase (eNOS) phosphorylation was significantly reduced in AMPK-DN cardiomyocytes, suggesting that the APN-eNOS signaling axis is impaired in AMPK-DN cardiomyocytes. Additional experiments demonstrated that treatment of AMPK-DN cardiomyocytes with gAPN reduced SI/R-induced NADPH oxidase overexpression, decreased superoxide generation, and blocked peroxynitrite formation to the same extent as that observed in WT cardiomyocytes. Collectively, our present study demonstrated that although the metabolic and eNOS activation effect of APN is largely mediated by AMPK, the superoxide-suppressing effect of APN is not mediated by AMPK, and this AMPK-independent antioxidant property of APN increased nitric oxide bioavailability and exerted significant antiapoptotic effect.