scholarly journals Inhibition of Type 2 Sodium-Glucose Transporters and Na+/H+ Exchanger-1 produces similar cardioprotective effects in response to ischemiareperfusion injury

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Bianca S. Blaettner ◽  
Hana E. Baker ◽  
Adam G. Goodwill ◽  
Hannah E. Clark ◽  
Michael C. Kozlowski ◽  
...  
Keyword(s):  
At Risk ◽  
Infarct Size ◽  
Reperfusion Injury ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Glucose Transporters ◽  
Left Ventricular ◽  
Area At Risk ◽  
Cardioprotective Effects

Background and Hypothesis: Recent studies indicate that inhibition of Type 2 Sodium-Glucose Transporters (SGLT2i) augments diastolic filling volume and mitigates myocardial ischemic injury. This study tested the hypothesis that inhibition of the Na+/H+ Exchanger-1 (NHE-1) mimics the cardioprotective effects of SGLT2i in response to ischemia-reperfusion injury. Experimental Design or Project Methods: Lean swine (~50 kg) were anesthetized, a thoracotomy performed, and perivascular flow transducers placed around the left anterior descending (LAD) and circumflex coronary (LCX) arteries. A pressure-volume (PV) catheter was then inserted into the left ventricle. Swine received a 15 min infusion of vehicle (DMSO; n = 3), the SGLT2i Canagliflozin (30 µM; n = 3), or the NHE-1 inhibitor Cariporide (1µM; n = 3) prior to a 60 min total occlusion of the LCX and 2-hour reperfusion period. Following reperfusion, the LCX was re-occluded and a 2.5% Patent Blue 5 solution was administered to identify area at risk. The heart was excised, sectioned, and incubated in a 2,3,5-triphenyltetrazolium chloride (TTC) solution. Images were collected and analyzed for area at risk and infarct size. Results: In the vehicle treated group, 2 of the 3 swine studied died prematurely before the completion of the protocol; one at baseline and one during ischemia. Our initial findings support that left ventricular end diastolic volume increases in response to regional myocardial ischemia in swine that received either Canagliflozin or Cariporide. This increase in diastolic volume was associated with an increase in stroke volume (i.e. Frank-Starling effect) and a reduction in myocardial infarct size in both treatment groups. Blood pressure tended to decrease to a similar extent in all groups. Conclusion and Potential Impact: These pilot studies suggest that inhibition of SGLT2 and NHE-1 produces similar functional and protective effects in response to regional ischemia-reperfusion injury. Further experiments are needed to corroborate these findings and examine the extent to which SGLT2i directly modulates NHE-1 activity.

Effects of Endotoxin on Neutrophil-Mediated Ischemia/Reperfusion Injury in the Rat Heart In Vivo

2001 ◽  
Vol 226 (4) ◽  
pp. 320-327 ◽  
Author(s):  
Brian P. Lipton ◽  
Joseph B. Delcarpio ◽  
Kathleen H. McDonough
Keyword(s):  
At Risk ◽  
Reperfusion Injury ◽  
Ischemia Reperfusion Injury ◽  
Isolated Heart ◽  
Ischemia Reperfusion ◽  
Left Ventricular ◽  
Necrotic Area ◽  
Area At Risk

We have previously shown that a nonlethal dose of lipopolysaccharide (LPS) decreases L-selectin expression of neutrophils (PMNs), thereby preventing PMN-mediated reperfusion injury in the isolated heart. In the present study we determined whether or not that dose of LPS would protect hearts during in vivo ischemia and reperfusion by preventing PMN-induced reperfusion injury. Rats receiving saline vehicle showed marked myocardial injury (necrotic area/area at risk = 82% ± 2%) and significant depression in left ventricular function as assessed in the isolated isovolumic heart preparation at constant flow rates of 5, 10, 15, and 20 ml/min. The administration of LPS (100 μg/kg body wt) 7 hr prior to ischemia resulted in a reduction in myocardial damage (necrotic area/area at risk = 42% ± 3%) and preservation of function. Myocardial function was similar to that of sham ischemic saline- and LPS-treated rats. Moreover, PMN infiltration as determined by histology was quantitatively more severe in hearts of saline-treated rats than in hearts of LPS-treated rats. Isolated hearts from vehicle- and LPS-treated animals undergoing sham ischemia in vivo recovered to the same extent after in vitro ischemia/reperfusion, suggesting that LPS did not induce protection by altering intrinsic properties of the heart. Our results indicate that LPS-induced protection of the heart from in vivo PMN-mediated ischemia/reperfusion injury may be due to decreased L-selectin expression of PMNs in LPS-treated animals.

Abstract 212: Cd4+ T-cell Activation By T-cell Receptor Engagement Contributes To Myocardial Ischemia-reperfusion Injury

2013 ◽  
Vol 113 (suppl_1) ◽  
Author(s):  
Ulrich Hofmann ◽  
Denise Mathes ◽  
Johannes Weirather ◽  
Niklas Beyersdorf ◽  
Thomas Kerkau ◽  
...  
Keyword(s):  
At Risk ◽  
T Cells ◽  
T Cell ◽  
Infarct Size ◽  
T Cell Receptor ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Cell Receptor ◽  
Area At Risk ◽  
Infarct Area

Background: We have recently shown that CD4 + but not CD8 + T-cells contribute to ischemia-reperfusion injury of the myocardium. We therefore hypothesized that CD4 + T-cells become activated by autoantigen recognition via their T-cell receptor during reperfusion. Methods and Results: Infarct size as percent of the area-at-risk was determined by combined Evans` blue and triphenyltetrazolium (TTC) staining after 30 minutes of in vivo ischemia followed by 24 hours reperfusion in mice. After 24 hours of reperfusion there was a significantly increased population of CD4 + T-cells which expressed the surface protein CD40L in comparison to sham operated mice [n≥7; p<0.05; WT 10.8 ± 0.2% vs. sham 6.4 ± 0.5%]. CD40L is typically expressed in T-cells activated by T-cell receptor engagement. OT-II mice carry a transgenic T-cell receptor with specificity for an ovalbumin-derived peptide. These mice have a limited T-cell receptor repertoire, dominated by specificity for the irrelevant antigen ovalbumin. After 30 minutes of ischemia and 24 hours of reperfusion OT-II mice showed significantly reduction in infarct size [n≥4; p= 0.02; infarct/area at risk: OTII mice 38.9 ± 2.4% vs. WT mice 63.7 ± 6.6 % ]. Administration of a CD40L blocking antibody to wildtype mice also reduced infarct size when compared to administration of isotype-matched antibodies [n≥6; p = 0.03; infarct/ area at risk: anti-CD154 treatment 60.4 ± 3.4% vs. control 75.3 ± 4.1%]. CD4 + CD25 + Foxp3 + T-cells (natural T-regulatory cells) have a low activation threshold and constitute a T-cell subset with reactivity against autoantigens. Depletion of these cells by diphtheria-toxin application in a mouse model expressing the diphtheria-toxin receptor under the Foxp3 promotor also resulted in a significant reduction of infarct size when compared to diphtheria-toxin treated wildtype mice [n≥4; p=0.03; infarct/ area at risk: T reg -depleted DEREG mice 51.9± 3% vs. WT littermates 72.3± 2%]. Conclusion: Our results indicate that CD4 + T-cells that have been activated by an MHC class II/ T-cell receptor dependent mechanism, presumably by autoantigen recognition, contribute to myocardial ischemia-reperfusion injury.

Mechanism of decreased adenosine protection in reperfusion injury of aging rats

2000 ◽  
Vol 279 (1) ◽  
pp. H329-H338 ◽  
Author(s):  
Feng Gao ◽  
Theodore A. Christopher ◽  
Bernard L. Lopez ◽  
Eitan Friedman ◽  
Guoping Cai ◽  
...  
Keyword(s):  
Myocardial Ischemia ◽  
Reperfusion Injury ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Left Ventricular ◽  
Protective Effects ◽  
No Release ◽  
Myocardial Ischemia Reperfusion Injury ◽  
Cardioprotective Effects ◽  
Myocardial Ischemia Reperfusion

The purpose of this study was to determine whether the protective effects of adenosine on myocardial ischemia-reperfusion injury are altered with age, and if so, to clarify the mechanisms that underlie this change related to nitric oxide (NO) derived from the vascular endothelium. Isolated perfused rat hearts were exposed to 30 min of ischemia and 60 min of reperfusion. In the adult hearts, administration of adenosine (5 μmol/l) stimulated NO release (1.06 ± 0.19 nmol · min−1 · g−1, P < 0.01 vs. vehicle), increased coronary flow, improved cardiac functional recovery (left ventricular developed pressure 79 ± 3.8 vs. 57 ± 3.1 mmHg in vehicle, P < 0.001; maximal rate of left ventricular pressure development 2,385 ± 103 vs. 1,780 ± 96 in vehicle, P < 0.001), and reduced myocardial creatine kinase loss (95 ± 3.9 vs. 159 ± 4.6 U/100 mg protein, P < 0.01). In aged hearts, adenosine-stimulated NO release was markedly reduced (+0.42 ± 0.12 nmol · min−1 · g−1 vs. vehicle), and the cardioprotective effects of adenosine were also attenuated. Inhibition of NO production in the adult hearts significantly decreased the cardioprotective effects of adenosine, whereas supplementation of NO in the aged hearts significantly enhanced the cardioprotective effects of adenosine. The results show that the protective effects of adenosine on myocardial ischemia-reperfusion injury are markedly diminished in aged animals, and that the loss in NO release in response to adenosine may be at least partially responsible for this age-related alteration.

scholarly journals Inhibition of Myocardial Ischemia/Reperfusion Injury by Exosomes Secreted from Mesenchymal Stem Cells

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Heng Zhang ◽  
Meng Xiang ◽  
Dan Meng ◽  
Ning Sun ◽  
Sifeng Chen
Keyword(s):  
Stem Cells ◽  
Mesenchymal Stem Cells ◽  
Left Ventricle ◽  
Reperfusion Injury ◽  
Ischemia Reperfusion Injury ◽  
Therapeutic Potential ◽  
Heart Function ◽  
Ischemia Reperfusion ◽  
Left Ventricular ◽  
Area At Risk

Exosomes secreted by mesenchymal stem cells have shown great therapeutic potential in regenerative medicine. In this study, we performed meta-analysis to assess the clinical effectiveness of using exosomes in ischemia/reperfusion injury based on the reports published between January 2000 and September 2015 and indexed in the PUBMED and Web of Science databases. The effect of exosomes on heart function was evaluated according to the following parameters: the area at risk as a percentage of the left ventricle, infarct size as a percentage of the area at risk, infarct size as a percentage of the left ventricle, left ventricular ejection fraction, left ventricular fraction shortening, end-diastolic volume, and end-systolic volume. Our analysis indicated that the currently available evidence confirmed the therapeutic potential of mesenchymal stem cell-secreted exosomes in the improvement of heart function. However, further mechanistic studies, therapeutic safety, and clinical trials are required for optimization and validation of this approach to cardiac regeneration after ischemia/reperfusion injury.

Blocking Na+/H+ exchange reduces [Na+]i and [Ca2+]i load after ischemia and improves function in intact hearts

2001 ◽  
Vol 281 (6) ◽  
pp. H2398-H2409 ◽  
Author(s):  
Jianzhong An ◽  
Srinivasan G. Varadarajan ◽  
Amadou Camara ◽  
Qun Chen ◽  
Enis Novalija ◽  
...  
Keyword(s):  
Guinea Pig ◽  
Infarct Size ◽  
Reperfusion Injury ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Ringer Solution ◽  
Left Ventricular ◽  
Isolated Hearts ◽  
Intracellular Ca ◽  
Ionic Basis

We determined in intact hearts whether inhibition of Na+/H+ exchange (NHE) decreases intracellular Na+ and Ca2+ during ischemia and reperfusion, improves function during reperfusion, and reduces infarct size. Guinea pig isolated hearts were perfused with Krebs-Ringer solution at 37°C. Left ventricular (LV) free wall intracellular Na+ concentration ([Na+]i) and intracellular Ca2+ concentration ([Ca2+]i) were measured using fluorescence dyes. Hearts were exposed to 30 min of ischemia with or without 10 μM of benzamide (BIIB-513), a selective NHE-1 inhibitor, infused for 10 min just before ischemia or for 10 min immediately on reperfusion. At 2 min of reperfusion, BIIB-513 given before ischemia decreased peak increases in [Na+]i and [Ca2+]i, respectively, from 2.5 and 2.3 times (controls) to 1.6 and 1.3 times preischemia values. At 30 min of reperfusion, BIIB-513 increased systolic-diastolic LV pressure (LVP) from 49 ± 2% (controls) to 80 ± 2% of preischemia values. BIIB-513 reduced ventricular fibrillation by 54% and reduced infarct size from 64 ± 1% to 20 ± 3%. First derivative of the LVP, O2 consumption, and cardiac efficiency were also improved by BIIB-513. Similar results were obtained with BIIB-513 given on reperfusion. These data show that Na+ loading is a marker of reperfusion injury in intact hearts in that inhibiting NHE reduces Na+ and Ca2+ loading during reperfusion while improving function. These results clearly implicate the ionic basis by which inhibiting NHE protects the guinea pig intact heart from ischemia-reperfusion injury.

scholarly journals Cardioprotective Effect of Novel Matrix Metalloproteinase Inhibitors

2020 ◽  
Vol 21 (19) ◽  
pp. 6990
Author(s):  
Kamilla Gömöri ◽  
Tamara Szabados ◽  
Éva Kenyeres ◽  
Judit Pipis ◽  
Imre Földesi ◽  
...  
Keyword(s):  
Matrix Metalloproteinase ◽  
Infarct Size ◽  
Reperfusion Injury ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Positive Control ◽  
Matrix Metalloproteinase 2 ◽  
Area At Risk ◽  
Triphenyltetrazolium Chloride

Background: We recently developed novel matrix metalloproteinase-2 (MMP-2) inhibitor small molecules for cardioprotection against ischemia/reperfusion injury and validated their efficacy in ischemia/reperfusion injury in cardiac myocytes. The aim of the present study was to test our lead compounds for cardioprotection in vivo in a rat model of acute myocardial infarction (AMI) in the presence or absence of hypercholesterolemia, one of the major comorbidities affecting cardioprotection. Methods: Normocholesterolemic adult male Wistar rats were subjected to 30 min of coronary occlusion followed by 120 min of reperfusion to induce AMI. MMP inhibitors (MMPI)-1154 and -1260 at 0.3, 1, and 3 µmol/kg, MMPI-1248 at 1, 3, and 10 µmol/kg were administered at the 25th min of ischemia intravenously. In separate groups, hypercholesterolemia was induced by a 12-week diet (2% cholesterol, 0.25% cholic acid), then the rats were subjected to the same AMI protocol and single doses of the MMPIs that showed the most efficacy in normocholesterolemic animals were tested in the hypercholesterolemic animals. Infarct size/area at risk was assessed at the end of reperfusion in all groups by standard Evans blue and 2,3,5-triphenyltetrazolium chloride (TTC) staining, and myocardial microvascular obstruction (MVO) was determined by thioflavine-S staining. Results: MMPI-1154 at 1 µmol/kg, MMPI-1260 at 3 µmol/kg and ischemic preconditioning (IPC) as the positive control reduced infarct size significantly; however, this effect was not seen in hypercholesterolemic animals. MVO in hypercholesterolemic animals decreased by IPC only. Conclusions: This is the first demonstration that MMPI-1154 and MMPI-1260 showed a dose-dependent infarct size reduction in an in vivo rat AMI model; however, single doses that showed the most efficacy in normocholesterolemic animals were abolished by hypercholesterolemia. The further development of these promising cardioprotective MMPIs should be continued with different dose ranges in the study of hypercholesterolemia and other comorbidities.

Deletion of the Semaphorin, Sema4D, but Not Inhibition of Sema4D Shedding by ADAM17, Impairs Platelet Function and Reduces Infarct Size After Myocardial Ischemia.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 771-771
Author(s):  
Li Zhu ◽  
Tao Wang ◽  
Hong Jiang ◽  
Timothy J. Stalker ◽  
Karen P. Fong ◽  
...  
Keyword(s):  
At Risk ◽  
T Cells ◽  
Endothelial Cells ◽  
Reperfusion Injury ◽  
Platelet Function ◽  
Ischemia Reperfusion Injury ◽  
Fetal Liver ◽  
Ischemia Reperfusion ◽  
Area At Risk ◽  
Fetal Liver Cells

Abstract Abstract 771 Introduction. Platelets are activated early during the reperfusion of ischemic myocardium, potentially exacerbating the extent of ischemia/reperfusion (I/R) injury. We have recently shown (Zhu, et al., PNAS 2007) that platelets express the semaphorin family member, sema4D, as do T-cells. Sema4D is a cell surface protein whose receptors are expressed by B-cells, monocytes and endothelial cells as well as platelets. Loss of sema4D expression in mice causes a defect in signaling downstream of the platelet collagen receptor, glycoprotein (GP) VI, inhibiting platelet function in vitro and in vivo, and reducing the extent of platelet hyperresponsiveness and atherothrombosis in the setting of dyslipidemia (Zhu, et al. ATVB 2009). Because of the role played by platelets, leukocytes and endothelial cells in reperfusion injury, here we asked whether loss of sema4D expression can also protect the heart, reducing the extent of damage following temporary ischemia. Methods. The left anterior descending coronary artery of anaesthetized mice was ligated for 45 min. After reperfusion for 48 hours, the mice were re-anesthetized and perfused with 2,3,5-triphenyltetrazolium chloride to measure the area of infarction. Fluorescent microspheres were used to delineate the area at risk. Comparisons were made between sema4D(−/−) and wild type mice produced by breeding sema4D(+/−) heterozygotes. Results. Although there was no difference between the sema4D(−/−) and WT mice with respect to either heart size or area at risk, we observed a substantial (57%) decrease in infarct size in the sema4D(−/−) mice expressed as a fraction of the area at risk (N=7-9, p<0.005). Since sema4D is shed from the surface of activated platelets and T-cells by the metalloprotease, ADAM17, producing a large bioactive fragment, we next asked whether the protection against ischemia/reperfusion injury conferred by the sema4D knockout is due to the loss of cell-associated or soluble sema4D. Chimeric mice were produced in which hematopoiesis was reconstituted in irradiated sema4D(+/+) mice using fetal liver cells from mouse embryos that lack functional ADAM17. This produces mice in which sema4D is expressed as usual in the hematopoietic lineages, but unable to be shed. Chimerism, inhibition of sema4D shedding and recovery of normal cell counts were confirmed after transplantation. The ischemia/reperfusion studies were repeated comparing chimeras reconstituted with ADAM17-deficient and ADAM17-replete fetal liver cells. In contrast to the sema4D knockout, the extent of infarction was the same whether or not ADAM17 was functional and sema4D was shed. Conclusions. Although the role of sema4D and its receptors have been studied most extensively in the context of T-cell interactions with B-cells, our previous studies have made a case for the involvement of sema4D in platelet:platelet and platelet:endothelial cell interactions. We now show for the first time that 1) loss of sema4D expression in mice confers protection against ischemia/reperfusion injury in the myocardium, and 2) preventing the formation of soluble, bioactive sema4D is insufficient to recapitulate this effect. Since sema4D and its receptors are expressed on more than just platelets, it cannot be concluded that the observed protection in the knockout is solely due to the absence of platelet sema4D. However, experience with other knockouts that reduce platelet function suggests that the defects that we have observed in sema4D(−/−) platelet function are likely to contribute. Regardless of whether expression on platelets is entirely or only partly responsible for the observed phenotype, sema4D is an interesting target for therapeutic intervention. Disclosures: No relevant conflicts of interest to declare.

PR-39 and PR-11 peptides inhibit ischemia-reperfusion injury by blocking proteasome-mediated IκBα degradation

2001 ◽  
Vol 281 (6) ◽  
pp. H2612-H2618 ◽  
Author(s):  
Jialin Bao ◽  
Kaori Sato ◽  
Min Li ◽  
Youhe Gao ◽  
Ruhul Abid ◽  
...  
Keyword(s):  
Infarct Size ◽  
Reperfusion Injury ◽  
Adhesion Molecule ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Neutrophil Infiltration ◽  
Left Ventricular ◽  
Myeloperoxidase Activity ◽  
Intramyocardial Injection ◽  
Iκbα Degradation

PR-39 inhibits proteasome-mediated IκBα degradation and might protect against ischemia-reperfusion injury. We studied PR-39, its truncated form PR-11, and a mutant PR-11AAA, which lacks the ability to prevent IκBα degradation, in a rat heart ischemia-reperfusion model. After 30 min of ischemia and 24 h of reperfusion, cardiac function, infarct size, neutrophil infiltration, and myeloperoxidase activity were measured. Intramyocardial injection of 10 nmol/kg PR-39 or PR-11 at the time of reperfusion reduced infarct size by 65% and 57%, respectively, which improved blood pressure, left ventricular systolic pressure, and relaxation and contractility (±dP/d t) compared with vehicle controls 24 h later. Neutrophil infiltration, myeloperoxidase activity, and the expression of intercellular adhesion molecule-1 and vascular cell adhesion molecule 1 were reduced. Thus PR-39 and PR-11 effectively inhibit myocardial ischemia-reperfusion injury in the rat in vivo. This effect is mediated by inhibition of IκBα degradation and subsequent inhibition of nuclear factor-κB-dependent adhesion molecules. The active sequence is located in the first 11 amino acids, suggesting a potential for oligopeptide therapy as an adjunct to revascularization.

Differential contribution of necrosis and apoptosis in myocardial ischemia-reperfusion injury

2004 ◽  
Vol 286 (5) ◽  
pp. H1923-H1935 ◽  
Author(s):  
James D. McCully ◽  
Hidetaka Wakiyama ◽  
Yng-Ju Hsieh ◽  
Mara Jones ◽  
Sidney Levitsky
Keyword(s):  
Infarct Size ◽  
Reperfusion Injury ◽  
Myocardial Injury ◽  
Caspase 3 ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Left Ventricular ◽  
Parp Cleavage ◽  
Control Group ◽  
Early Reperfusion

Necrosis and apoptosis differentially contribute to myocardial injury. Determination of the contribution of these processes in ischemia-reperfusion injury would allow for the preservation of myocardial tissue. Necrosis and apoptosis were investigated in Langendorff-perfused rabbit hearts ( n = 47) subjected to 0 (Control group), 5 (GI-5), 10 (GI-10), 15 (GI-15), 20 (GI-20), 25 (GI-25), and 30 min (GI-30) of global ischemia (GI) and 120 min of reperfusion. Myocardial injury was determined by triphenyltetrazolium chloride (TTC) staining, terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL), bax, bcl2, poly(ADP)ribose polymerase (PARP) cleavage, caspase-3, -8, and -9 cleavage and activity, Fas ligand (FasL), and Fas-activated death domain (FADD). The contribution of apoptosis was determined separately ( n = 42) using irreversible caspase-3, -8, and -9 inhibitors. Left ventricular peak developed pressure (LVPDP) and systolic shortening (SS) were significantly decreased and infarct size and TUNEL-positive cells were significantly increased ( P < 0.05 vs. Control group) at GI-20, GI-25, and GI-30. Proapoptotic bax, PARP cleavage, and caspase-3 and -9 cleavage and activity were apparent at GI-5 to GI-30. Fas, FADD, and caspase-8 cleavage and activity were unaltered. Irreversible inhibition of caspase-3 and -9 activity significantly decreased ( P < 0.05) infarct size at GI-25 and GI-30 but had no effect on LVPDP or SS. Myocardial injury results from a significant increase in both necrosis and apoptosis ( P < 0.05 vs. Control group) evident by TUNEL, TTC staining, and caspase activity at GI-20. Intrinsic proapoptotic activation is evident early during ischemia but does not significantly contribute to infarct size before GI-25. The contribution of necrosis to infarct size at GI-20, GI-25, and GI-30 is significantly greater than that of apoptosis. Apoptosis is significantly decreased by caspase inhibition during early reperfusion, but this protection does not improve immediate postischemic functional recovery.

Cardioprotective effects of rosiglitazone are associated with selective overexpression of type 2 angiotensin receptors and inhibition of p42/44 MAPK

2006 ◽  
Vol 291 (2) ◽  
pp. H687-H693 ◽  
Author(s):  
Behzad Molavi ◽  
Jiawei Chen ◽  
J. L. Mehta
Keyword(s):  
Myocardial Ischemia ◽  
Infarct Size ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Control Diet ◽  
Diet Group ◽  
Ang Ii ◽  
Ppar Γ ◽  
Cardioprotective Effects

Current evidence points to renin-angiotensin system as a key mediator in ischemia-reperfusion injury. Rosiglitazone, a peroxisome proliferator-activated receptor-γ (PPAR-γ) ligand, has recently been shown to confer cardioprotection against ischemia-reperfusion in animal models. We sought to examine the expression of ANG II receptors during PPAR-γ-mediated cardioprotection. Male Sprague-Dawley rats (nondiabetic) were fed either regular rat chow (control diet group, n = 9) or rosiglitazone-rich diet (rosiglitazone-rich diet group, n = 9) and were subjected to 1 h of myocardial ischemia followed by 1 h of reperfusion. A third group of rats had only thoracotomy and pericardiotomy and served as a sham control group ( n = 9). Hemodynamics, infarct size, and expression of ANG II type 1 and type 2 receptors (AT1 and AT2) were measured in all groups. There was a 58% reduction of infarct size in the rosiglitazone-rich diet group ( P < 0.01 vs. control diet group). Increased myocardial expression of AT1 receptors in the ischemic-reperfused myocardium was attenuated in the rosiglitazone-rich diet group ( P < 0.05 vs. control diet group). Importantly, myocardial AT2 mRNA and protein expression were significantly increased (by >100-fold) in the rosiglitazone-rich diet group ( P < 0.05). These changes were accompanied by inhibition of p42/44 MAPK in the rosiglitazone-rich diet group, while the Akt1 expression, believed to mediate insulin sensitization, remained similar in all three groups. The cardioprotective effects of rosiglitazone against myocardial ischemia-reperfusion injury are independent of its insulin-sensitizing properties and are associated with significant overexpression of AT2 receptors along with inhibition of p42/44 MAPK.

Sign in / Sign up

Export Citation Format

Share Document