Abstract 18: Increasing in vivo Apoa1/HDL Levels Negates the Cardiotoxic Effects of Doxorubicin, and Involves Signalling Through SR-BI, PI3K, and AKT1

2015 ◽  
Vol 117 (suppl_1) ◽  
Author(s):  
Kristina Durham ◽  
Cyrus Thomas ◽  
Bernardo L Trigatti
Keyword(s):  
Fold Increase ◽  
Left Ventricular ◽  
Cardiomyocyte Apoptosis ◽  
Cross Sectional ◽  
Over Expression ◽  
Pressure Development ◽  
Reduced Rate ◽  
Induced Apoptosis ◽  
Developed Pressure

Doxorubicin (DOX) is a clinically used anti-tumor drug, though the use of DOX is limited by its potent cardiotoxic side effect that can lead to heart failure. HDL protects isolated cardiomyocytes against DOX induced apoptosis, though whether this effect translates in vivo has yet to be determined. Here we assess whether ApoA1/HDL overexpression can protect mice in vivo against DOX induced cardiotoxicity, and explore the intracellular signalling mechanisms involved in protection. Mice overexpressing human ApoA1 (ApoA1tg/tg) and ApoA1+/+ mice were treated chronically with DOX, and effects on cardiac function and cardiomyocyte health were assessed. Over expression of human ApoA1 in mice corresponded to ~2.5 fold increase in plasma HDL-C as compared to ApoA1+/+ mice. Following 5 weekly injections of 5mg/kg DOX, ApoA1+/+ mice displayed cardiac dysfunction as evidenced by reduced left ventricular developed pressure, and reduced rate of pressure development. In contrast, left ventricular function was maintained following DOX treatment in ApoA1tg/tg mice. Histological analysis revealed reduced cardiomyocyte cross-sectional area and increased cardiomyocyte apoptosis following DOX treatment in ApoA1+/+ mice. ApoA1tg/tg mice, on the other hand, were protected against DOX induced cardiomyocyte atrophy and apoptosis. Interestingly, pAKT:tAKT was reduced in ApoA1+/+ by treatment with DOX, but the ratio was maintained in ApoA1tg/tg mice. We evaluated the roles of SR-BI, PI3K, and AKT1/2 in the signalling cascade of HDL in neonatal mouse cardiomyocytes and human immortalized ventricular cardiomyocytes. Through inhibition of AKT and PI3K, and knockdown or knockout of SR-BI, AKT1, and AKT2, we demonstrated that SR-BI, PI3K and AKT1 are required for HDL mediated protection against DOX induced cardiomyocyte apoptosis. Our results provide evidence for ApoA1 mediated protection against DOX cardiotoxicity in vivo and demonstrate the roles of SR-BI, PI3K, and AKT1 as mediators in the protective effect.

scholarly journals Sex-related effects on diabetes-induced alterations in calcium release in the rat heart

2007 ◽  
Vol 293 (6) ◽  
pp. H3584-H3592 ◽  
Author(s):  
Nazmi Yaras ◽  
Erkan Tuncay ◽  
Nuhan Purali ◽  
Babur Sahinoglu ◽  
Guy Vassort ◽  
...  
Keyword(s):  
Calcium Release ◽  
Binding Protein ◽  
Ryanodine Receptors ◽  
Left Ventricular ◽  
Adult Rats ◽  
Fk506 Binding Protein ◽  
Pressure Development ◽  
Spatiotemporal Parameters ◽  
Intracellular Ca ◽  
Developed Pressure

The present study was designed to determine whether the properties of local Ca2+ release and its related regulatory mechanisms might provide insight into the role of sex differences in heart functions of control and streptozotocin-induced diabetic adult rats. Left ventricular developed pressure, the rates of pressure development and decay (±dP/d t), basal intracellular Ca2+ level ([Ca2+]i), and spatiotemporal parameters of [Ca2+]i transients were found to be similar in male and female control rats. However, spatiotemporal parameters of Ca2+ sparks in cardiomyocytes isolated from control females were significantly larger and slower than those in control males. Diabetes reduced left ventricular developed pressure to a lower extent in females than in males, and the diabetes-induced depressions in both +dP/d t and −dP/d t were less in females than in males. Diabetes elicited a smaller reduction in the amplitude of [Ca2+]i transients in females than in males, a smaller reduction in sarcoplasmic reticulum-Ca2+ load, and less increase in basal [Ca2+]i. Similarly, the elementary Ca2+ events and their control proteins were clearly different in both sexes, and these differences were more marked in diabetes. Diabetes-induced depression of the Ca2+ spark amplitude was significantly less in females than in matched males. Levels of cardiac ryanodine receptors (RyR2) and FK506-binding protein 12.6 in control females were significantly higher than those shown in control males. Diabetes induced less RyR2 phosphorylation and FK506-binding protein 12.6 unbinding in females. Moreover, total and free sulfhydryl groups were significantly less reduced, and PKC levels were less increased, in diabetic females than in diabetic males. The present data related to local Ca2+ release and its related proteins describe some of the mechanisms that may underlie sex-related differences accounting for females to have less frequent development of cardiac diseases.

Abstract P293: Endogenous Lats2 Plays an Important Role in Mediating Myocardial Injury Caused by Ischemia/Reperfusion Through Inhibition of FoxO3

2011 ◽  
Vol 109 (suppl_1) ◽  
Author(s):  
Dan Shao ◽  
Peiyong Zhai ◽  
Junichi Sadoshima
Keyword(s):  
Oxidative Stress ◽  
Myocardial Injury ◽  
Ischemia Reperfusion ◽  
Systolic Pressure ◽  
Left Ventricular ◽  
Dominant Negative ◽  
Area At Risk ◽  
Perfused Heart ◽  
Developed Pressure

Lats2 is a tumor suppressor and a serine/threonine kinase, acting downstream of mammalian sterile 20 like kinase1 (Mst1), which stimulates apoptosis and inhibits hypertrophy in cardiomyocytes (CM). We investigated the role of Lats2 in mediating myocardial injury after ischemia/reperfusion (IR). Phosphorylation of YAP, an in vivo substrate of Lats2, was increased after 45 minutes ischemia followed by 24 hours reperfusion in control mouse hearts compared with sham, but not in dominant negative (DN) Lats2 transgenic mouse (Tg) hearts, suggesting that Lats2 is activated by IR. The size of myocardial infarction (MI)/area at risk was significantly smaller in Tg mice than in NTg mice (19% and 49%, p<0.01). And there were fewer TUNEL positive cells in Tg than in NTg mice (0.04% and 0.11%, p<0.05). Following 30 min of global ischemia and 60 min of reperfusion in Langendorff perfused heart preparations, left ventricular (LV) systolic pressure (100 vs 71mmHg, p<0.05) and LV developed pressure (79 vs 47 mmHg, p<0.05) were significantly greater in Tg than in NTg mice, indicating that suppression of Lats2 induces better functional recovery after IR. Oxidative stress, as evaluated by 8-OHdG staining, was attenuated in Tg mice. In cultured CMs, DN-Lats2 significantly decreased H 2 O 2 -induced cell death. Overexpression of Lats2 significantly downregulated (51% and 75%, p<0.05), whereas that of DN-Last2 upregulated (100 and 70%, p<0.05), MnSOD and catalase, suggesting that Lats2 negatively regulates expression of antioxidants. Reporter gene assays showed that overexpression of Lats2 significantly inhibits (−70%), whereas knocking down Lats2 by sh-Lats2 increases (+60%), FoxO3-mediated transcriptional activity. Overexpression of Lats2 in CMs inhibited FoxO3 expression, whereas that of DN-Lats2 significantly inhibited FoxO3 downregulation after IR in vivo, suggesting that Lats2 negatively regulates FoxO3 protein expression, which may lead to the downregulation of MnSOD and catalase. Taken together, these results suggest that endogenous Lats2 plays an important role in mediating myocardial injury in response to IR, In part through downregulation of FoxO3 and consequent downregulation of antioxidants and increased oxidative stress in the heart.

Severe myocardial dysfunction induced by ventricular remodeling in aging rat hearts

1990 ◽  
Vol 259 (4) ◽  
pp. H1086-H1096 ◽  
Author(s):  
J. M. Capasso ◽  
T. Palackal ◽  
G. Olivetti ◽  
P. Anversa
Keyword(s):  
Ventricular Remodeling ◽  
Volume Fraction ◽  
Diastolic Pressure ◽  
Structural Characteristics ◽  
Myocardial Dysfunction ◽  
Pressure Rise ◽  
Wall Stress ◽  
Left Ventricular ◽  
Cross Sectional

To determine if aging engenders alterations in the functional properties of the myocardium and ventricular remodeling, the hemodynamic performance and structural characteristics of the left ventricle of male Fischer 344 rats at 4, 12, 20, and 29 mo of age were studied by quantitative physiology and morphology. In vivo assessment of cardiac pump function showed no change up to 20 mo, whereas left ventricular end-diastolic pressure was increased at 29 mo. Moreover, peak rates of pressure rise and decay, stroke volume, ejection fraction, and cardiac output were depressed at the later age interval, demonstrating the presence of ventricular failure at this time. The measurements of chamber size and wall thickness showed that ventricular end-diastolic and end-systolic volumes progressively increased with age with the greatest change occurring at 20-29 mo. Aging was also accompanied by a marked augmentation in the volume fraction of fibrotic areas in the ventricular myocardium that was due to an increase in their number and cross-sectional area with time. These architectural rearrangements, in combination with the abnormalities in ventricular function, resulted in an elevation in the volume of wall stress throughout the cardiac cycle. Wall stress increased by 64, 44, and 50% from 4 to 12, 12 to 20, and 20 to 29 mo of age. In conclusion, aging leads to a continuous rise in wall stress that is not normalized by ventricular remodeling. These two independent processes appear to be responsible for the onset of heart failure in the senescent rat.

Myocardial reperfusion injury management: erythropoietin compared with postconditioning

2009 ◽  
Vol 297 (6) ◽  
pp. H2035-H2043 ◽  
Author(s):  
Sophie Tamareille ◽  
Nehmat Ghaboura ◽  
Frederic Treguer ◽  
Dalia Khachman ◽  
Anne Croué ◽  
...  
Keyword(s):  
Infarct Size ◽  
Reperfusion Injury ◽  
Isolated Heart ◽  
Ischemia Reperfusion ◽  
Left Ventricular ◽  
Myocardial Reperfusion ◽  
Myocardial Reperfusion Injury ◽  
Gsk 3Β ◽  
Developed Pressure

Ischemic postconditioning (IPost) and erythropoietin (EPO) have been shown to attenuate myocardial reperfusion injury using similar signaling pathways. The aim of this study was to examine whether EPO is as effective as IPost in decreasing postischemic myocardial injury in both Langendorff-isolated-heart and in vivo ischemia-reperfusion rat models. Rat hearts were subjected to 25 min ischemia, followed by 30 min or 2 h of reperfusion in the isolated-heart study. Rats underwent 45 min ischemia, followed by 24 h of reperfusion in the in vivo study. In both studies, the control group ( n = 12; ischemia-reperfusion only) was compared with IPost ( n = 16; 3 cycles of 10 s reperfusion/10 s ischemia) and EPO ( n = 12; 1,000 IU/kg) at the onset of reperfusion. The following resulted. First, in the isolated hearts, IPost or EPO significantly improved postischemic recovery of left ventricular developed pressure. EPO induced better left ventricular developed pressure than IPost at 30 min of reperfusion (73.18 ± 10.23 vs. 48.11 ± 7.92 mmHg, P < 0.05). After 2 h of reperfusion, the infarct size was significantly lower in EPO-treated hearts compared with IPost and control hearts (14.36 ± 0.60%, 19.11 ± 0.84%, and 36.21 ± 4.20% of the left ventricle, respectively; P < 0.05). GSK-3β phosphorylation, at 30 min of reperfusion, was significantly higher with EPO compared with IPost hearts. Phosphatidylinositol 3-kinase and ERK1/2 inhibitors abolished both EPO- and IPost-mediated cardioprotection. Second, in vivo, IPost and EPO induced an infarct size reduction compared with control (40.5 ± 3.6% and 28.9 ± 3.1%, respectively, vs. 53.7 ± 4.3% of the area at risk; P < 0.05). Again, EPO decreased significantly more infarct size and transmurality than IPost ( P < 0.05). In conclusion, with the use of our protocols, EPO showed better protective effects than IPost against reperfusion injury through higher phosphorylation of GSK-3β.

scholarly journals miR-24 inhibits apoptosis and represses Bim in mouse cardiomyocytes

2011 ◽  
Vol 208 (3) ◽  
pp. 549-560 ◽  
Author(s):  
Li Qian ◽  
Linda W. Van Laake ◽  
Yu Huang ◽  
Siyuan Liu ◽  
Michael F. Wendland ◽  
...  
Keyword(s):  
Cardiac Disease ◽  
Cardiac Dysfunction ◽  
Therapeutic Strategy ◽  
Cardiomyocyte Apoptosis ◽  
Border Zone ◽  
Cellular Processes ◽  
Promote Cell Survival ◽  
Induced Apoptosis ◽  
Normal Cardiac Function

Acute myocardial infarction (MI) involves necrotic and apoptotic loss of cardiomyocytes. One strategy to salvage ischemic cardiomyocytes is to modulate gene expression to promote cell survival without disturbing normal cardiac function. MicroRNAs (miRNAs) have emerged as powerful regulators of multiple cellular processes, including apoptosis, suggesting that regulation of miRNA function could serve a cardioprotective function. In this study, we report that miR-24 (miRNA-24) expression is down-regulated in the ischemic border zone of the murine left ventricle after MI. miR-24 suppresses cardiomyocyte apoptosis, in part by direct repression of the BH3-only domain–containing protein Bim, which positively regulates apoptosis. In vivo expression of miR-24 in a mouse MI model inhibited cardiomyocyte apoptosis, attenuated infarct size, and reduced cardiac dysfunction. This antiapoptotic effect on cardiomyocytes in vivo was partially mediated by Bim. Our results suggest that manipulating miRNA levels during stress-induced apoptosis may be a novel therapeutic strategy for cardiac disease.

Chronic infarction decreases maximum cardiac work and sensitivity of heart to extracellular calcium

1985 ◽  
Vol 249 (1) ◽  
pp. H80-H87 ◽  
Author(s):  
E. Fellenius ◽  
C. A. Hansen ◽  
O. Mjos ◽  
J. R. Neely
Keyword(s):  
Adenine Nucleotides ◽  
Creatine Phosphate ◽  
Scar Tissue ◽  
Left Ventricular ◽  
Compensatory Hypertrophy ◽  
Tissue Mass ◽  
Pressure Development ◽  
Whole Heart

Rat hearts were infarcted in vivo by ligation of the left ventricular coronary artery to cause an initial 40% loss of viable tissue by weight. Due to compensatory hypertrophy of the surviving myocardium and progression of the infarct to scar tissue, the infarct represented approximately 25% by weight of the whole heart after 1 wk. After 1 or 3 wk, these infarcted hearts were removed and perfused in vitro by the working hearts technique. Ventricular pressure development and positive dP/dt were lower in infarcted hearts compared with sham-operated ones. O2 consumption and glucose utilization by viable tissue per unit pressure development was the same in normal and infarcted hearts. Levels of creatine phosphate and free creatine were decreased, but ATP and total adenine nucleotides were well maintained. The inotropic response to decreases in extracellular [Ca2+] was much greater in infarcted hearts than in sham controls. Prenalterol increased ventricular function proportionally more in infarcted than in the sham-operated hearts, suggesting that down regulation of beta receptors was not a problem. The infarcted hearts were much more sensitive to verapamil than control hearts. It is concluded that the depressed function of the noninfarcted tissue of chronically infarcted hearts is due in part to loss of functioning tissue mass and in part to decreased sensitivity to extracellular Ca2+.

Altered sensitivity of chronic diabetic rat heart to calcium

1983 ◽  
Vol 245 (6) ◽  
pp. E560-E567 ◽  
Author(s):  
D. R. Bielefeld ◽  
C. S. Pace ◽  
B. R. Boshell
Keyword(s):  
Rat Heart ◽  
Calcium Metabolism ◽  
Left Ventricular Pressure ◽  
Calcium Sensitivity ◽  
Diabetic Rats ◽  
Left Ventricular ◽  
Diabetic Rat ◽  
Isolated Hearts ◽  
Pressure Development

An alteration in calcium metabolism in cardiac muscle was observed in diabetic rats 3 mo after streptozotocin treatment. Depression of cardiac output and left ventricular pressure development were more sensitive to decreased extra-cellular calcium in hearts from diabetic than from control animals and occurred within the normal physiological range of freely ionized serum calcium. This decrease in calcium sensitivity was not present after 2 wk of diabetes. In vivo treatment with insulin for 1 mo completely reversed the effect. Addition of octanoate (0.3 mM) to the perfusate of isolated hearts completely reversed the defect, whereas epinephrine (25 nM) only partially reversed it. When the glucose concentration of the perfusate was decreased, the function of diabetic hearts declined and was further diminished at decreasing calcium levels. Hearts from normal rats were unaffected. These results suggest that there is a defect in calcium metabolism or flux in the chronic diabetic rat heart.

Glibenclamide improves postischemic recovery of myocardial contractile function in trained and sedentary rats

2001 ◽  
Vol 91 (4) ◽  
pp. 1545-1554 ◽  
Author(s):  
Korinne N. Jew ◽  
Russell L. Moore
Keyword(s):  
Contractile Function ◽  
Ischemia Reperfusion ◽  
Left Ventricular ◽  
Treadmill Running ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Diastolic Stiffness ◽  
Pressure Development ◽  
Increased Sensitivity ◽  
Developed Pressure

In this study, we sought to determine whether there was any evidence for the idea that cardiac ATP-sensitive K+ (KATP) channels play a role in the training-induced increase in the resistance of the heart to ischemia-reperfusion (I/R) injury. To do so, the effects of training and an KATP channel blocker, glibenclamide (Glib), on the recovery of left ventricular (LV) contractile function after 45 min of ischemia and 45 min of reperfusion were examined. Female Sprague-Dawley rats were sedentary (Sed; n = 18) or were trained (Tr; n = 17) for >20 wk by treadmill running, and the hearts from these animals used in a Langendorff-perfused isovolumic LV preparation to assess contractile function. A significant increase in the amount of 72-kDa class of heat shock protein was observed in hearts isolated from Tr rats. The I/R protocol elicited significant and substantial decrements in LV developed pressure (LVDP), minimum pressure (MP), rate of pressure development, and rate of pressure decline and elevations in myocardial Ca2+ content in both Sed and Tr hearts. In addition, I/R elicited a significant increase in LV diastolic stiffness in Sed, but not Tr, hearts. When administered in the perfusate, Glib (1 μM) elicited a normalization of all indexes of LV contractile function and reductions in myocardial Ca2+content in both Sed and Tr hearts. Training increased the functional sensitivity of the heart to Glib because LVDP and MP values normalized more quickly with Glib treatment in the Tr than the Sed group. The increased sensitivity of Tr hearts to Glib is a novel finding that may implicate a role for cardiac KATP channels in the training-induced protection of the heart from I/R injury.

scholarly journals Abnormal Expression of MST1 and YAP1 in Fetal Heart Tissue in a Hyperglycemic Environment and Their Roles in Mediating Apoptosis

2020 ◽  
Author(s):  
Dongmei Su ◽  
Yanhua Li ◽  
Lina Guan ◽  
Qian Li ◽  
Cuige Shi ◽  
...  
Keyword(s):  
Diabetes Mellitus ◽  
Western Blot ◽  
Congenital Heart Defects ◽  
Congenital Heart ◽  
Heart Defects ◽  
Maternal Diabetes ◽  
Cardiomyocyte Apoptosis ◽  
Induced Apoptosis

Abstract Background：Gestational diabetes mellitus is a risk factor for congenital heart defects. The article aimed to investigate the expression and roles of Mst1, Yap1, Last1/2 and Survivin in modulating HG-induced cardiomyocyte apoptosis and maternal diabetes-induced heart abnormality. Methods：The gene and protein expression were assessed by quantitative PCR, western blot, and immunohistochemical staining. The protein phosphorylation level were analyzed by western blot .Knockdown of gene expression were assessed by RNA interference. Hoechst 33342 staining assay were performed to explore H9C2 apoptosis. Diabetes mellitus was induced in rats using streptozotocin.Results：Our results revealed that increased MST1 protein levels in the heart tissues of the offspring of diabetic rats in vivo occurred concomitantly with HG-induced apoptosis in H9C2 cardiomyocytes in vitro. Knockdown and overexpression experiments showed that MST1 played a key role in mediating HG-induced apoptosis in cardiomyocytes. Downregulation of YAP1 was associated with HG-induced, MST1-mediated cardiomyocyte apoptosis. Further study showed that MST1 downregulated the protein level of YAP1 through mediation of YAP1 phosphorylation on Ser127 and Ser397; this process also required LATS1/2 participation. MST1 overexpression increased the phosphorylation levels of LATS1/2, which were also shown to be increased in the heart tissues of diabetic offspring. We also found that YAP1 mediated the expression of Survivin during HG-induced apoptosis, and the Survivin-inhibitor YM155 partially inhibited the role of YAP1 in suppressing apoptosis induced by HG in cardiomyocytes. Conclusion：These findings reveal a regulatory mechanism of MST1/YAP1/Survivin signaling in modulating cardiomyocyte apoptosis in vitro and maternal diabetes-induced congenital heart defects in vivo.

Abstract 455: FGF23-induced Cardiac Hypertrophy is Reversible

2016 ◽  
Vol 119 (suppl_1) ◽  
Author(s):  
Alexander Grabner ◽  
Saurav Singh ◽  
Karla Schramm ◽  
Christopher Yanucil ◽  
Brian Czaya ◽  
...  
Keyword(s):  
Cardiac Myocytes ◽  
Cardiac Injury ◽  
Elevated Serum ◽  
Left Ventricular ◽  
Normal Diet ◽  
Cross Sectional ◽  
Blocking Antibody ◽  
High Phosphate

Left ventricular hypertrophy (LVH) is a common feature of cardiovascular disease in chronic kidney disease (CKD) and affects up to 90% of patients by the time they reach dialysis. Serum levels of fibroblast growth factor (FGF) 23 continuously rise as patients progress to renal failure. We have previously shown that FGF23 can activate FGF receptor (FGFR) 4 and the PLCgamma/calcineurin/NFAT signaling cascade in cardiac myocytes and induce hypertrophy in vitro and in vivo. Administration of an isoform-specific FGFR4 blocking antibody in the 5/6 nephrectomy rat model of CKD immediately after surgery protects rats from developing LVH, and delivery of a pan-FGFR blocker in CKD rats two weeks after surgery reverses LVH. To further study the reversibility of cardiac FGF23 effects, we elevated serum FGF23 levels in mice by administration of a high phosphate (2%) diet for three months. Animals developed LVH, as evident by significantly increased LV wall thickness and myocyte cross sectional area. When mice were switch from high phosphate to normal chow, the LVH phenotype resolved and cardiac parameters were comparable to those of mice that constantly received a normal diet. Furthermore, isolated cardiac myocytes recovered within 24 hours from FGF23-induced hypertrophy upon removal of FGF23. Finally, the FGFR4 blocking antibody was capable of reversing FGF23-induced hypertrophy in vitro. Our data indicate that FGF23-induced LVH is reversible and treatable. Interfering with FGF23/FGFR4 signaling in the heart might provide a novel therapeutic strategy to tackle cardiac injury in CKD. We propose that progression and reversibility of cardiac injury might depend on the duration of cardiac FGF23/FGFR4 activation.

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