Attenuation of ischemia–reperfusion-induced alterations in intracellular Ca2+ in cardiomyocytes from hearts treated with N-acetylcysteine and N-mercaptopropionylglycineThis article is one of a selection of papers published in a special issue on Advances in Cardiovascular Research.

2009 ◽  
Vol 87 (12) ◽  
pp. 1110-1119 ◽  
Author(s):  
Harjot K. Saini-Chohan ◽  
Naranjan S. Dhalla
Keyword(s):  
Oxidative Stress ◽  
Diastolic Pressure ◽  
Ischemia Reperfusion ◽  
Redox Status ◽  
Left Ventricular ◽  
Cardiovascular Research ◽  
Rat Hearts ◽  
Intracellular Ca ◽  
Developed Pressure ◽  
Selection Of

This study was undertaken to test whether Ca2+-handling abnormalities in cardiomyocytes after ischemia–reperfusion (I/R) are prevented by antioxidants such as N-acetyl l-cysteine (NAC), which is known to reduce oxidative stress by increasing the glutathione redox status, and N-(2-mercaptopropionyl)-glycine (MPG), which scavenges both peroxynitrite and hydroxyl radicals. For this purpose, isolated rat hearts were subjected to 30 min of global ischemia followed by 30 min of reperfusion, and cardiomyocytes were prepared to monitor changes in the intracellular concentration of free Ca2+ ([Ca2+]i). Marked depression in the left ventricular developed pressure and elevation in the left ventricular end-diastolic pressure in I/R hearts were attenuated by treatment with NAC or MPG. Cardiomyocytes obtained from I/R hearts showed an increase in the basal level of [Ca2+]i as well as augmentation of the low Na+-induced increase in [Ca2+]i, with no change in the KCl-induced increase in [Ca2+]i. These I/R-induced alterations in Ca2+ handling by cardiomyocytes were attenuated by treatment of hearts with NAC or MPG. Furthermore, reduction in the isoproterenol-, ATP-, ouabain-, and caffeine-induced increases in [Ca2+]i in cardiomyocytes from I/R hearts were limited by treatment with NAC or MPG. The increases in the basal [Ca2+]i, unlike the KCl-induced increase in [Ca2+]i, were fully or partially prevented by both NAC and MPG upon exposing cardiomyocytes to hypoxia–reoxygenation, H2O2, or a mixture of xanthine and xanthine oxidase. These results suggest that improvement in cardiac function of I/R hearts treated with NAC or MPG was associated with attenuation of changes in Ca2+ handling by cardiomyocytes, and the results support the view that oxidative stress due to oxyradical generation and peroxynitrite formation plays an important role in the development of intracellular Ca2+ overload in cardiomyocytes as a consequence of I/R injury.

Role of oxidative stress in alterations of mitochondrial function in ischemic-reperfused hearts

2007 ◽  
Vol 292 (4) ◽  
pp. H1986-H1994 ◽  
Author(s):  
Zhanna Makazan ◽  
Harjot K. Saini ◽  
Naranjan S. Dhalla
Keyword(s):  
Oxidative Stress ◽  
Oxidative Phosphorylation ◽  
Mitochondrial Function ◽  
Mitochondrial Respiration ◽  
Diastolic Pressure ◽  
Ischemia Reperfusion ◽  
Respiratory Control ◽  
Left Ventricular ◽  
Cardiac Performance ◽  
Developed Pressure

To study the mechanisms of mitochondrial dysfunction due to ischemia-reperfusion (I/R) injury, rat hearts were subjected to 20 or 30 min of global ischemia followed by 30 min of reperfusion. After recording both left ventricular developed pressure (LVDP) and end-diastolic pressure (LVEDP) to monitor the status of cardiac performance, mitochondria from these hearts were isolated to determine respiratory and oxidative phosphorylation activities. Although hearts subjected to 20 min of ischemia failed to generate LVDP and showed a marked increase in LVEDP, no changes in mitochondrial respiration and phosphorylation were observed. Reperfusion of 20-min ischemic hearts depressed mitochondrial function significantly but recovered LVDP completely and lowered the elevated LVEDP. On the other hand, depressed LVDP and elevated LVEDP in 30-min ischemic hearts were associated with depressions in both mitochondrial respiration and oxidative phosphorylation. Reperfusion of 30-min ischemic hearts elevated LVEDP, attenuated LVDP, and decreased mitochondrial state 3 and uncoupled respiration, respiratory control index, ADP-to-O ratio, as well as oxidative phosphorylation rate. Alterations of cardiac performance and mitochondrial function in I/R hearts were attenuated or prevented by pretreatment with oxyradical scavenging mixture (superoxide dismutase and catalase) or antioxidants [ N-acetyl-l-cysteine or N-(2-mercaptopropionyl)-glycine]. Furthermore, alterations in cardiac performance and mitochondrial function due to I/R were simulated by an oxyradical-generating system (xanthine plus xanthine oxidase) and an oxidant (H2O2) either upon perfusing the heart or upon incubation with mitochondria. These results support the view that oxidative stress plays an important role in inducing changes in cardiac performance and mitochondrial function due to I/R.

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.

Ischemia–reperfusion-induced changes in sarcolemmal Na+/K+-ATPase are due to the activation of calpain in the heartThis article is one of a selection of papers published in a Special Issue on Oxidative Stress in Health and Disease.

2010 ◽  
Vol 88 (3) ◽  
pp. 388-397 ◽  
Author(s):  
Raja B. Singh ◽  
Naranjan S. Dhalla
Keyword(s):  
Oxidative Stress ◽  
Cardiac Function ◽  
Atpase Activity ◽  
Protein Content ◽  
Ischemia Reperfusion ◽  
Specific Inhibitor ◽  
Calpain Activity ◽  
Rat Hearts ◽  
Intracellular Ca ◽  
Calpain Inhibitors

Depression in cardiac performance due to ischemia–reperfusion (I/R) injury is associated with the development of oxidative stress and decreased sarcolemmal (SL) Na+/K+-ATPase activity. Since both I/R and oxidative stress have been reported to promote the occurrence of intracellular Ca2+ overload and activate proteases such as calpain, this study was undertaken to investigate whether the activation of calpain in I/R hearts is associated with alterations in the SL Na+/K+-ATPase activity and its isoform content. For this purpose, isolated rat hearts treated with and without 2 different calpain inhibitors (leupeptin and MDL28170) were subjected to 30 min ischemia followed by 60 min of reperfusion, and the cardiac function, SL Na+/K+-ATPase activity, Na+/K+-ATPase isoform protein content, and calpain activity were measured. The I/R-induced depressions in cardiac function, Na+/K+-ATPase activity, and protein content of Na+/K+-ATPase isoforms were associated with an increase in calpain activity , but were prevented by treatment of hearts with leupeptin. Incubation of SL membranes with calpain decreased the Na+/K+-ATPase activity and protein content of its isoforms; these changes were also attenuated by leupeptin. The I/R-induced alterations in cardiac function and the activity of SL Na+/K+-ATPase and calpain were Ca2+-dependent and were prevented by MDL28170, a specific inhibitor of calpain. The I/R-induced translocation of calpain isoforms (I and II) from the cytosol to SL and the changes in distribution of calpastatin were also attenuated by treatment with calpain inhibitors. These results suggest that the depression in cardiac function and SL Na+/K+-ATPase activity in I/R hearts may be due to changes in the activity and translocation of calpain.

Inhibition of the creatine kinase reaction decreases the contractile reserve of isolated rat hearts

1995 ◽  
Vol 269 (3) ◽  
pp. H1030-H1036 ◽  
Author(s):  
B. L. Hamman ◽  
J. A. Bittl ◽  
W. E. Jacobus ◽  
P. D. Allen ◽  
R. S. Spencer ◽  
...  
Keyword(s):  
Creatine Kinase ◽  
Dynamic Range ◽  
Acute Stress ◽  
Diastolic Pressure ◽  
Left Ventricular ◽  
Stress Conditions ◽  
Contractile Reserve ◽  
Phosphoryl Transfer ◽  
Rat Hearts ◽  
Developed Pressure

To define the relation between phosphoryl transfer via creatine kinase (CK) and the ability of the intact beating heart to do work, we chemically inhibited CK activity and then measured cardiac performance under physiological and acute stress conditions. Isolated perfused rat hearts were exposed to iodoacetamide (IA) and subjected to one of three cardiac stresses: hypercalcemic (Ca2+ = 3 mM) buffer perfusion (n = 7), norepinephrine (2 mumol/min) infusion (n = 6), or hypoxic buffer perfusion (n = 5). IA decreased CK activity to near zero, measured in intact hearts by 31P magnetization transfer, and to 2% of control CK activity, measured in myocardial homogenates. The CK isoenzyme profile was unchanged, suggesting nonselective IA inhibition of all isoenzymes. Mitochondria isolated from IA-treated hearts had normal ADP:O ratios, state 3 respiratory rates, and unchanged acceptor and respiratory control ratios. Neither actomyosin adenosinetriphosphatase nor adenylate kinase activities were changed. After IA exposure, end-diastolic pressure, left ventricular developed pressure, and heart rate were unchanged for at least 30 min at physiological perfusion pressures, but large changes were observed during stress conditions. The increase in left ventricular developed pressure induced by hypercalcemic perfusion and by norepinephrine infusion decreased by 39 and 54%, respectively. During hypoxia, the rate of phosphocreatine depletion was decreased by 57%, left ventricular developed pressure declined, and end-diastolic pressure increased faster than in controls. These results show that inhibition of CK to < 2% of control activity by IA reduced contractile reserve by approximately 50%. We conclude that CK activity is essential for the expression of the full dynamic range of myocardial performance.

scholarly journals Hemidesmus indicusandHibiscus rosa-sinensisAffect Ischemia Reperfusion Injury in Isolated Rat Hearts

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Vinoth Kumar Megraj Khandelwal ◽  
R. Balaraman ◽  
Dezider Pancza ◽  
Táňa Ravingerová
Keyword(s):  
Infarct Size ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Left Ventricular ◽  
Moderate Increase ◽  
Dependent Manner ◽  
Hemidesmus Indicus ◽  
Rat Hearts ◽  
Perfused Rat Hearts ◽  
Developed Pressure

Hemidesmus indicus(L.) R. Br. (HI) andHibiscus rosa-sinensisL. (HRS) are widely used traditional medicine. We investigated cardioprotective effects of these plants applied for 15 min at concentrations of 90, 180, and 360 μg/mL in Langendorff-perfused rat hearts prior to 25-min global ischemia/120-min reperfusion (I/R). Functional recovery (left ventricular developed pressure—LVDP, and rate of development of pressure), reperfusion arrhythmias, and infarct size (TTC staining) served as the endpoints. A transient increase in LVDP (32%–75%) occurred at all concentrations of HI, while coronary flow (CF) was significantly increased after HI 180 and 360. Only a moderate increase in LVDP (21% and 55%) and a tendency to increase CF was observed at HRS 180 and 360. HI and HRS at 180 and 360 significantly improved postischemic recovery of LVDP. Both the drugs dose-dependently reduced the numbers of ectopic beats and duration of ventricular tachycardia. The size of infarction was significantly decreased by HI 360, while HRS significantly reduced the infarct size at all concentrations in a dose-dependent manner. Thus, it can be concluded that HI might cause vasodilation, positive inotropic effect, and cardioprotection, while HRS might cause these effects at higher concentrations. However, further study is needed to elucidate the exact mechanism of their actions.

Attenuation of postischemic reperfusion injury is related to prevention of [Ca2+]m overload in rat hearts

1996 ◽  
Vol 271 (5) ◽  
pp. H2145-H2153 ◽  
Author(s):  
M. Miyamae ◽  
S. A. Camacho ◽  
M. W. Weiner ◽  
V. M. Figueredo
Keyword(s):  
Reperfusion Injury ◽  
Calcium Concentration ◽  
Diastolic Pressure ◽  
Left Ventricular ◽  
Ruthenium Red ◽  
Free Calcium ◽  
Postischemic Reperfusion ◽  
Rat Hearts ◽  
Free Calcium Concentration ◽  
Developed Pressure

Intracellular calcium overload has been implicated in postischemic reperfusion injury. In myocytes, mitochondrial free calcium concentration ([Ca2+]m), not cytosolic free calcium concentration ([Ca2+]c), overload is related to reoxygenation injury. We tested the hypothesis that [Ca2+]m, not [Ca2+]c, overload is an important mediator of reperfusion injury in whole hearts. [Ca2+]m and [Ca2+]c were assessed using indo 1 fluorescence in isolated rat hearts subjected to 45 min of ischemia and 20 min of reperfusion. Ruthenium red (RR), a selective inhibitor of mitochondrial calcium uptake at 0.025 microM, attenuated the increase of [Ca2+]m (4% RR vs. 57% control) over preischemic levels (230 +/- 10 nM) but did not affect the increase of systolic [Ca2+]c (990 +/- 100 nM RR vs. 1,010 +/- 130 nM control). This was associated with improved recovery of left ventricular developed pressure (61% RR vs. 37% control) and attenuation of the increase of diastolic pressure (34 mmHg RR vs. 47 mmHg control). Contractile recovery was related to the degree of [Ca2+]m overload in both control and RR hearts (r2 = 0.47, P = 0.001). This study is the first to demonstrate that [Ca2+]m, and not [Ca2+]c, overload is related to reperfusion injury in intact beating hearts.

Sarpogrelate diminishes changes in energy stores and ultrastructure of the ischemic-reperfused rat heart

2001 ◽  
Vol 79 (9) ◽  
pp. 761-767 ◽  
Author(s):  
Rana M Temsah ◽  
Hideo Kumamoto ◽  
Nobuakira Takeda ◽  
Naranjan S Dhalla
Keyword(s):  
Serotonin Receptor ◽  
Diastolic Pressure ◽  
Ischemia Reperfusion ◽  
Cardiac Injury ◽  
High Energy ◽  
Left Ventricular ◽  
Receptor Blockade ◽  
Vascular Abnormalities ◽  
Reperfusion Period ◽  
Developed Pressure

Although the involvement of serotonin in exacerbating vascular abnormalities in ischemic heart disease has been established, its role in mediating changes in cardiac function due to ischemia reperfusion (IR) is poorly understood. The aim of this study was to investigate the effect of a serotonin blocker, sarpogrelate (5-HT2A antagonist), in preventing cardiac injury due to IR. Isolated rat hearts were subjected to 30 min of global ischemia followed by 1 h of reperfusion. Sarpogrelate (50 nM-0.9 µM) was infused 10 min before ischemia as well as during the reperfusion period. The IR-induced changes in left ventricular developed pressure, left ventricular end diastolic pressure, rate of pressure development, and rate of pressure decay were attenuated (P < 0.05) with sarpogrelate treatment. Sarpogrelate also decreased the ultrastructural damage and improved the high energy phosphate level in the IR hearts (P < 0.05). This study provides evidence for the attenuation of IR-induced cardiac injury by 5-HT2A receptor blockade and supports the view that serotonin may contribute to the deleterious effects of IR in the heart.Key words: ischemia reperfusion, sarpogrelate, serotonin receptor blockade.

scholarly journals Pleiotropic Effects of Simvastatin Are Associated With Mitigation of Apoptotic Component of Cell Death Upon Lethal Myocardial Reperfusion-Induced Injury

2012 ◽  
pp. S33-S41 ◽  
Author(s):  
T. RAJTÍK ◽  
S. ČARNICKÁ ◽  
A. SZOBI ◽  
L. MESÁROŠOVÁ ◽  
M. MÁŤUŠ ◽  
...  
Keyword(s):  
Cell Death ◽  
Ischemia Reperfusion ◽  
Active Form ◽  
Plasma Lipid ◽  
Left Ventricular ◽  
Control Group ◽  
Rat Hearts ◽  
Pleiotropic Action ◽  
Developed Pressure ◽  
Transcription 3

Although statins exert non-lipid cardioprotective effects, their influence on cell death is not fully elucidated. For this purpose, we investigated whether simvastatin treatment (S, 10 mg/kg, 5 days) is capable of mitigating ischemia/reperfusion-induced (IR) apoptosis in the isolated rat hearts, which was examined using immunoblotting analysis. In addition, the content of signal transducer and activator of transcription 3 (STAT3) and its active form, phosphorylated STAT3 (pSTAT3-Thr705), was analyzed. Simvastatin induced neither variations in the plasma lipid levels nor alterations in the baseline content of analysed proteins with the exception of upregulation of cytochrome C. Furthermore, simvastatin significantly increased the baseline levels of pSTAT3 in contrast to the control group. In the IR hearts, simvastatin reduced the expression of Bax and non-cleaved caspase-3. In these hearts, phosphorylation of STAT3 did not differ in comparison to the non-treated IR group, however total STAT3 content was slightly increased. The improved recovery of left ventricular developed pressure co-existed with the increased Bcl-2/Bax ratio. In conclusion, pleiotropic action of statins may ameliorate viability of cardiomyocytes by favouring the expression of anti-apoptotic Bcl-2 and downregulating the pro-apoptotic markers; however STAT3 does not seem to be a dominant regulator of this anti-apoptotic action of simvastatin.

Abstract 38: A Decoy Peptide Selectively Inhibiting Dephosphorylation of Phospholamban

2012 ◽  
Vol 111 (suppl_1) ◽  
Author(s):  
Woo Jin Park ◽  
Jae Gyun Oh ◽  
Dongtak Jeong ◽  
Roger J Hajjar
Keyword(s):  
Ischemia Reperfusion ◽  
Left Ventricular ◽  
Cardiac Sarcoplasmic Reticulum ◽  
Rat Cardiomyocytes ◽  
Adult Rat ◽  
Rat Hearts ◽  
Cell Permeable Peptide ◽  
Phosphorylated Peptide ◽  
Developed Pressure

Cardiac sarcoplasmic reticulum Ca2+ ATPase (SERCA2a) plays a crucial role in Ca2+ handling in cardiomyocytes. Phospholamban (PLB) is an endogenous inhibitor of SERCA2a and its inhibitory activity is enhanced by dephosphorylation by protein phosphatase 1 (PP1). Therefore, blocking PP1-mediated dephosphorylation of PLB would be an efficient strategy for restoration of the reduced SERCA2a activity in failing hearts. We sought to develop a decoy peptide that mimics the phosphorylated PLB and thus competitively inhibits the PP1-mediated dephosphorylation of PLB. The phosphorylation sites, Ser16 and Thr17, are located within the flexible extra-membrane loop (amino acids 14-22) of PLB. We therefore synthesized a 9-mer pseudo-phosphorylated peptide derived from this region with a replacement of Ser16 with Glu (ψ-PLB-SE). Two other 9-mer peptides with wild type PLB sequence (ψ-PLB) or with a replacement of Ser16 with Ala (ψ-PLB-SA) were also synthesized. These peptides were coupled to a cell-permeable peptide TAT to facilitate cellular uptake. Treatment of adult rat cardiomyocytes with TAT-ψ-PLB-SE, but not with TAT-ψ-PLB or TAT-ψ-PLB-SA, significantly elevated the phosphorylation level of PLB, concomitant with an increase in contractile parameters in vitro. Perfusion of isolated rat hearts with TAT-ψ-PLB-SE significantly restored the left ventricular developed pressure that was suppressed by ischemia-reperfusion (Fig. 1). These data indicate that ψ-PLB-SE prevented dephosphorylation of PLB by acting as a decoy for PP1 and it would provide effective modality to regulate SERCA2a activity in failing hearts.

Effects of the AT1 Receptor Blocker Candesartan on Myocardial Ischemia/Reperfusion in Isolated Rat Hearts

2014 ◽  
Vol 17 (5) ◽  
pp. 263 ◽  
Author(s):  
C. Murat Songur ◽  
Merve Ozenen Songur ◽  
Sinan Sabit Kocabeyoglu ◽  
Bilgen Basgut
Keyword(s):  
Reperfusion Injury ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Left Ventricular ◽  
Relaxation Rates ◽  
Cardioplegic Solution ◽  
Rat Hearts ◽  
Developed Pressure ◽  
Contraction And Relaxation ◽  
Isolated Rat

<p><b>Background:</b> We sought to investigate the effects of the angiotension II receptor blocker candesartan on ischemia-reperfusion injury using a cardioplegia arrested isolated rat heart model.</p><p><b>Methods:</b> Ischemia-reperfusion injury was induced in isolated rat hearts with 40 minutes of global ischemia followed by a 30-minute reperfusion protocol. Throughout the experiment, constant pressure perfusion was achieved using a Langendorff apparatus. Cardioplegic solution alone, and in combination with candesartan, was administered before ischemia and 20 minutes after ischemia. Post-ischemic recovery of contractile function, left ventricular developed pressure, left ventricular end-diastolic pressure and contraction and relaxation rates were evaluated.</p><p><b>Results:</b> In the control group, left ventricular developed pressure, rate pressure product, contraction and relaxation rates and coronary flow significantly decreased but coronary resistance increased following reperfusion. With the administration of candesartan alone, parameters did not differ compared to controls. Contractile parameters improved in the group that received candesartan in combination with the cardioplegia compared to the group that received cardioplegia alone; however, the difference between these two groups was insignificant.</p><p><b>Conclusion:</b> In this study, the addition of candesartan to a cardioplegic arrest protocol routinely performed during cardiac surgery did not provide a significant advantage in protection against ischemia-reperfusion injury compared with the administration of cardioplegic solution alone.</p>

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