Insulin improves cardiac myocytes contractile function recovery in simulated ischemia-reperfusion: Key role of Akt

2003 ◽  
Vol 48 (13) ◽  
pp. 1364-1369 ◽  
Author(s):  
Bo Zhang ◽  
Haifeng Zhang ◽  
Qian Fan ◽  
Xinliang Ma ◽  
Feng Gao
Keyword(s):  
Cardiac Myocytes ◽  
Contractile Function ◽  
Ischemia Reperfusion ◽  
Simulated Ischemia ◽  
Function Recovery

scholarly journals STAT subtype specificity and ischemic preconditioning in mice: is STAT-3 enough?

2011 ◽  
Vol 300 (2) ◽  
pp. H522-H526 ◽  
Author(s):  
Michael D. Goodman ◽  
Sheryl E. Koch ◽  
Muhammad R. Afzal ◽  
Karyn L. Butler
Keyword(s):  
Ischemic Preconditioning ◽  
Ischemia Reperfusion Injury ◽  
Contractile Function ◽  
Ex Vivo ◽  
Ischemia Reperfusion ◽  
Cardiac Performance ◽  
Subtype Specificity ◽  
Developed Pressure ◽  
Perfused Hearts

The role of other STAT subtypes in conferring ischemic tolerance is unclear. We hypothesized that in STAT-3 deletion alternative STAT subtypes would protect myocardial function against ischemia-reperfusion injury. Wild-type (WT) male C57BL/6 mice or mice with cardiomyocyte STAT-3 knockout (KO) underwent baseline echocardiography. Langendorff-perfused hearts underwent ischemic preconditioning (IPC) or no IPC before ischemia-reperfusion. Following ex vivo perfusion, hearts were analyzed for STAT-5 and -6 phosphorylation by Western blot analysis of nuclear fractions. Echocardiography and postequilibration cardiac performance revealed no differences in cardiac function between WT and KO hearts. Phosphorylated STAT-5 and -6 expression was similar in WT and KO hearts before perfusion. Contractile function in WT and KO hearts was significantly impaired following ischemia-reperfusion in the absence of IPC. In WT hearts, IPC significantly improved the recovery of the maximum first derivative of developed pressure (+dP/d tmax) compared with that in hearts without IPC. IPC more effectively improved end-reperfusion dP/d tmax in WT hearts compared with KO hearts. Preconditioned and nonpreconditioned KO hearts exhibited increased phosphorylated STAT-5 and -6 expression compared with WT hearts. The increased subtype activation did not improve the efficacy of IPC in KO hearts. In conclusion, baseline cardiac performance is preserved in hearts with cardiac-restricted STAT-3 deletion. STAT-3 deletion attenuates preconditioning and is not associated with a compensatory upregulation of STAT-5 and -6 subtypes. The activation of STAT-5 and -6 in KO hearts following ischemic challenge does not provide functional compensation for the loss of STAT-3. JAK-STAT signaling via STAT-3 is essential for effective IPC.

Annexin V staining during reperfusion detects cardiomyocytes with unique properties

2001 ◽  
Vol 281 (5) ◽  
pp. H1931-H1937 ◽  
Author(s):  
Prakash Narayan ◽  
Robert M. Mentzer ◽  
Robert D. Lasley
Keyword(s):  
Propidium Iodide ◽  
Ventricular Myocytes ◽  
Contractile Function ◽  
Ischemia Reperfusion ◽  
Annexin V ◽  
Cell Width ◽  
Simulated Ischemia ◽  
Propidium Iodide Staining ◽  
Membrane Blebs ◽  
Apoptosis And Necrosis

With the use of markers of sarcolemmal membrane permeability, cardiomyocyte models of ischemic injury have primarily addressed necrotic death during ischemia. In the present study, we used annexin V-propidium iodide staining to examine apoptosis and necrosis after simulated ischemia and simulated reperfusion in rat ventricular myocytes. Annexin V binds phosphatidylserine, a phosphoaminolipid thought to be externalized during apoptosis or programmed cell death. Propidium iodide is a marker of cell necrosis. Under baseline conditions, <1% of cardiomyocytes stained positive for annexin V. After 20 or 60 min of simulated ischemia, there was no increase in annexin V staining, although 60-min simulated ischemia resulted in significant propidium iodide staining. Twenty minutes of simulated ischemia, followed by 20 or 60 min of simulated reperfusion, resulted in 8–10% of myocytes staining positive for annexin V. Annexin V-positive cells retained both rod-shaped morphology and contractile function but exhibited the decreased cell width indicative of cell shrinkage. Baseline mitochondrial free Ca2+(111 ± 14 nM) was elevated in reperfused annexin V-negative cells (214 ± 22 nM), and further elevated in annexin V-positive myocytes (382 ± 9 nM). After 60 min of simulated reperfusion, caspase-3-like activity was observed in ∼3% of myocytes, which had a rounded appearance and membrane blebs. These results suggest that the use of annexin V after simulated ischemia-reperfusion uncovers a population of cardiomyocytes whose characteristics appear to be consistent with cells undergoing apoptosis.

scholarly journals Overexpression of A3 adenosine receptors decreases heart rate, preserves energetics, and protects ischemic hearts

2002 ◽  
Vol 283 (4) ◽  
pp. H1562-H1568 ◽  
Author(s):  
Heather R. Cross ◽  
Elizabeth Murphy ◽  
Richard G. Black ◽  
John Auchampach ◽  
Charles Steenbergen
Keyword(s):  
Heart Rate ◽  
Contractile Function ◽  
Ischemia Reperfusion ◽  
Specific Inhibitor ◽  
Left Ventricular ◽  
Atp Depletion ◽  
Wild Type ◽  
Basal Heart Rate ◽  
Developed Pressure

To determine whether A3 adenosine receptor (A3AR) signaling modulates myocardial function, energetics, and cardioprotection, hearts from wild-type and A3AR-overexpressor mice were subjected to 20-min ischemia and 40-min reperfusion while 31P NMR spectra were acquired. Basal heart rate and left ventricular developed pressure (LVDP) were lower in A3AR-overexpressor hearts than wild-type hearts. Ischemic ATP depletion was delayed and postischemic recoveries of contractile function, ATP, and phosphocreatine were greater in A3AR-hearts. To determine the role of depressed heart rate and to confirm A3AR-specific signaling, hearts were paced at 480 beats/min with or without 60 nmol/l MRS-1220 (A3AR-specific inhibitor) and then subjected to ischemia-reperfusion. LVDP was similar in paced A3AR-overexpressor and paced wild-type hearts. Differences in ischemic ATP depletion and postischemic contractile and energetic dysfunction remained in paced A3AR-overexpressor hearts versus paced wild-type hearts but were abolished by MRS-1220. In summary, A3AR overexpression decreased basal heart rate and contractility, preserved ischemic ATP, and decreased postischemic dysfunction. Pacing abolished the decreased contractility but not the ATP preservation or cardioprotection. Therefore, A3AR overexpression results in cardioprotection via a specific A3AR effect, possibly involving preservation of ATP during ischemia.

Role of cGMP-PKG signaling in the protection of neonatal rat cardiac myocytes subjected to simulated ischemia/reoxygenation

2010 ◽  
Vol 105 (5) ◽  
pp. 643-650 ◽  
Author(s):  
Aniko Gorbe ◽  
Zoltan Giricz ◽  
Andrea Szunyog ◽  
Tamas Csont ◽  
Dwaine S. Burley ◽  
...  
Keyword(s):  
Cardiac Myocytes ◽  
Neonatal Rat ◽  
Simulated Ischemia ◽  
Neonatal Rat Cardiac Myocytes ◽  
Rat Cardiac Myocytes

Concurrent opposite effects of trichostatin A, an inhibitor of histone deacetylases, on expression of α-MHC and cardiac tubulins: implication for gain in cardiac muscle contractility

2005 ◽  
Vol 288 (3) ◽  
pp. H1477-H1490 ◽  
Author(s):  
Francesca J. Davis ◽  
Jyothish B Pillai ◽  
Madhu Gupta ◽  
Mahesh P. Gupta
Keyword(s):  
Cardiac Myocytes ◽  
Histone Deacetylases ◽  
Contractile Function ◽  
Trichostatin A ◽  
In Vivo Model ◽  
Ang Ii ◽  
Cardiac Contractile Function ◽  
Noticeable Effect

Histone deacetylases (HDACs) are a family of enzymes that catalyze the removal of acetyl groups from core histones, resulting in change of chromatin structure and gene transcription activity. In the heart, HDACs are targets of hypertrophic signaling, and their nonspecific inhibition by trichostatin A (TSA) attenuates hypertrophy of cultured cardiac myocytes. In this study, we examined the effect of TSA on two major determinants of cardiac contractility: α-myosin heavy chain (MHC) expression and microtubular composition and organization. TSA upregulated the expression of α-MHC in cultured cardiac myocytes, as well as in an in vivo model of hypothyroid rats. Studies designed to delineate mechanisms of α-MHC induction by TSA revealed an obligatory role of early growth response factor-1 on activation of the α-MHC promoter. Concurrently, TSA downregulated the expression of α- and β-tubulins and prevented the induction of tubulins by a hypertrophy agonist, ANG II. The ANG II-mediated increased proportion of α- and β-tubulins associated with polymerized microtubules was also markedly reduced after treatment of cells by TSA. Results obtained from immunofluorescent microscopy indicated that TSA had no noticeable effect on the organization of cardiac microtubules in control cells, whereas it prevented the ANG II-induced dense parallel linear arrays of microtubules to a profile similar to that of controls. Together, these results demonstrate that inhibition of HDACs by TSA regulates the cardiac α-MHC and tubulins in a manner predictive of improved cardiac contractile function. These studies improve our understanding of the role of HDACs on cardiac hypertrophy with implications in development of new therapeutic agents for treatment of cardiac abnormalities.

Mechanisms of Erythropoietin-Mediated Cardioprotection during Ischemia-Reperfusion Injury: Role of Protein Kinase C Signaling.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 2907-2907
Author(s):  
Murat O. Arcasoy ◽  
Paul Hanlon ◽  
Ping Fu ◽  
Charles Steenbergen ◽  
Elizabeth Murphy
Keyword(s):  
Protein Kinase ◽  
Reperfusion Injury ◽  
Ischemia Reperfusion Injury ◽  
Contractile Function ◽  
Ischemia Reperfusion ◽  
Cardioprotective Effect ◽  
Isolated Perfused Heart ◽  
Perfused Heart ◽  
Biologic Effects

Abstract The biologic effects of erythropoietin (EPO) are mediated by its cellular receptor EPOR, a member of the cytokine receptor superfamily. EPOR expression in non-hematopoietic cells is associated with novel biologic effects for EPO in diverse organ systems. We recently demonstrated functional EPOR expression in adult rat cardiac myocytes and found that recombinant EPO exerts a rapid cardioprotective effect during ischemia-reperfusion injury of the isolated, perfused heart. Here we investigated the mechanisms of the cardioprotective effect of EPO using Langendorff-perfused rat hearts while left-ventricular-developed pressure (LVDP) was measured continuously to assess contractile function. Hearts were treated directly with EPO in the presence or absence of inhibitors of specific signal transduction pathways prior to normothermic global ischemia followed by reperfusion. Post-ischemic recovery of contractile function was determined by measuring LVDP at the end of reperfusion and expressed as a percentage of the baseline pre-treatment measurement. We investigated EPO-mediated activation of signal transduction pathways in the isolated, perfused heart and observed phosphorylation of p44/p42 MAP kinases ERK 1/2 (Thr202/Tyr204) and protein kinase B/Akt (Ser473), a downstream target of the phosphatidylinositol 3-kinase (PI3K) signaling pathway. Furthermore, EPO treatment of the isolated, perfused heart was associated with translocation of protein kinase C (PKC) ε and δ isoforms to the membrane fraction. We investigated the role of specific signaling pathways in EPO-mediated cardioprotection by employing inhibitors targeting PI3K, PKC and MAP kinase kinase (MEK1). PI3K inhibitors LY294002 and wortmannin attenuated EPO-induced phosphorylation of Akt but had no effect on EPO-mediated cardioprotection. MEK1 inhibitor U0126 had no effect on EPO-mediated cardioprotection. The PKC catalytic inhibitor chelerythrine (chel) significantly inhibited EPO-mediated improvement in post-ischemic recovery of LVDP (figure 1). Hearts pre-treated with EPO exhibited significantly improved post-ischemic recovery of LVDP compared to control hearts (mean±SE: 72±3 in EPO-treated versus 35±3% in control hearts, P<0.05 by ANOVA and Bonferroni post-hoc test, n=10 experiments each group) and the protective effect of EPO was significantly inhibited in chel-treated hearts (52±4% in EPO+chel versus 72±3% in EPO-treated hearts, P<0.05, n=10). As a control, treatment of the hearts with chelerythrine alone had no significant effect on LVDP (49±4%) compared to control hearts. These data demonstrate that EPO-mediated activation of the PKC signaling pathway is required for the cardioprotective effect of EPO during ischemia-reperfusion injury. Figure Figure

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