Abstract 235: Ischemia-Reperfusion Injury Decreases Myocardial Hydration Potential Without Changing Flow Resistance in the Interstitial Matrix

2012 ◽  
Vol 111 (suppl_1) ◽  
Author(s):  
Maria P McGee ◽  
Michael Morykwas ◽  
James Jordan ◽  
Louis Argenta
Keyword(s):  
At Risk ◽  
Flow Resistance ◽  
Ischemia Reperfusion Injury ◽  
Ex Vivo ◽  
Ischemia Reperfusion ◽  
P Value ◽  
Mechanical Forces ◽  
Interstitial Flow ◽  
Elastic Recoil ◽  
Fluid Accumulation

Interstitial edema is an early response to myocardial ischemia, leading to fibrosis and remodeling in several heart failure conditions. We aimed to clarify whether osmotic, frictional, or mechanical forces drive fluid accumulation. Equilibrium and dynamic interstitial hydration parameters were determined, compared, and analyzed using osmotic stress approaches in explants from ischemic and nonischemic myocardial regions of pig heart. They were isolated after injury induced by ligating 3-4 branches of the left anterior descending coronary artery, for 85 min followed by 3 hours’ reperfusion. Their volume changed (Δ V max ) linearly with colloidosmotic pressure in both ischemic and nonischemic areas, yielding interstitial compliance values of 1.04 ± 0.09 and 1.08 ± 0.05 µl/g/ mmHg , which do not differ significantly, and hydration potentials from the abscissa intercepts at Δ V max = 0, of -121.4 ± 28 and -14.7 ± 7.6 mmHg, which do (mean ± SE, n = 5 , P-value = 0.001). These hydration potential differences manifest ex-vivo influx rates 8.5 ± 2.7- fold slower in ischemic than nonischemic myocardium. Surprisingly, interstitial flow resistance values derived from net-flow rates at an imposed pressure difference of 216 mmHg were 0.23 ± 0.08 and 0.19 ± 0.01 µl -1 . g. min and did not differ significantly between the areas. The similarity in interstitial compliance and fluid resistance indicates that the more negative hydration potential and faster efflux rates in at-risk regions after reperfusion are due to increased hydrostatic pressure rather than decreased osmotic or frictional forces. Tissue distends due to interstitial fluid accumulation against matrix mechanical forces, including elastic recoil of the collagen elastin mesh and fibroblast action, consistent with impaired drainage and persistent diastolic-like conditions during reperfusion of at-risk areas in vivo . These results indicate changes in pressure gradient magnitude and may have clinical and therapeutic implications; for example, reversal of paracrine interstitial flows during early remodeling

Abstract 061: Interstitial Matrix Flow-Regulation:Myocardial Fibroblasts Respond to Colloidosmotic Pressure

2013 ◽  
Vol 113 (suppl_1) ◽  
Author(s):  
Maria P McGee ◽  
Michael Morykwas ◽  
Rui Wang ◽  
James Jordan ◽  
Louis Argenta
Keyword(s):  
At Risk ◽  
Reperfusion Injury ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Linear Regression Analysis ◽  
P Value ◽  
Control Mechanisms ◽  
Collagen Gels ◽  
Fluid Transfer

Ischemia-reperfusion injury induces large differences in hydration potential between ischemic and nonischemic areas of the myocardium. They influence the rate and volume of fluid transfer in myocardial explants; temperature-dependent hydration-potential differences of approximately 100 mmHg in at-risk areas, as opposed to contiguous areas that are not at risk, suggest prompt interstitial fluid-transfer control mechanisms (Circ. Res . 2012;11:A235) . Aim: We adapted osmotic-stress techniques to determine whether myocardial fibroblasts, which are known to respond to mechanical and flow signals, also respond to hydration-potential changes. Methods: Fibroblasts were isolated from midwall regions of the left ventricles of healthy pigs using standard procedures. They were incorporated into 3-dimensional collagen gels of 500 mm 3 volume at 150 cells/mm 3 and equilibrated overnight in cultures using the nontoxic, inert polymer polyethylene glycol 8000 (molecular radius ~26.5 Å; concentration range 0-10% w/w) to adjust colloidosmotic pressure from approximately 5 to 205 mmHg . After the gels were detached from the dish, fluid flux was derived from any time-dependent changes in their dimensions. Results: The volume of gels without fibroblasts did not change significantly at any coloidosmotic pressure. In those with fibroblasts, the volume decreased, more slowly in those subjected to higher-than-plasma pressure levels. Progression curves conformed well to a two-exponential term model (R 2 >0.9) suggesting that two parallel processes contribute to matrix efflux, one relatively fast, with decay constant 0.274 ± 0.014 (n = 3) , and another ~50-fold slower. Initial rates were calculated from the fitted curves, and linear regression analysis used to examine their dependence on colloidosmotic pressure. Initial efflux rates decreased with pressure, mean slope, - 0.29 ± 0.08 µl/h/mmHg (R 2 = 0.7; P-value = 0.006). Conclusion: In vitro , fibroblasts in collagen matrices regulate fluid efflux in response to colloidosmotic stresses within the range of hydration-potential differences measured in myocardial explants after ischemia-reperfusion injury.

scholarly journals Cardioprotective Effects of PPARβ/δ Activation against Ischemia/Reperfusion Injury in Rat Heart Are Associated with ALDH2 Upregulation, Amelioration of Oxidative Stress and Preservation of Mitochondrial Energy Production

2021 ◽  
Vol 22 (12) ◽  
pp. 6399
Author(s):  
Ioanna Papatheodorou ◽  
Eleftheria Galatou ◽  
Georgios-Dimitrios Panagiotidis ◽  
Táňa Ravingerová ◽  
Antigone Lazou
Keyword(s):  
Oxidative Stress ◽  
Mrna Expression ◽  
Energy Production ◽  
Citrate Synthase ◽  
Ischemia Reperfusion Injury ◽  
Ex Vivo ◽  
Uncoupling Protein ◽  
Ischemia Reperfusion ◽  
Left Ventricular ◽  
Isocitrate Dehydrogenase 2

Accumulating evidence support the cardioprotective properties of the nuclear receptor peroxisome proliferator activated receptor β/δ (PPARβ/δ); however, the underlying mechanisms are not yet fully elucidated. The aim of the study was to further investigate the mechanisms underlying PPARβ/δ-mediated cardioprotection in the setting of myocardial ischemia/reperfusion (I/R). For this purpose, rats were treated with PPARβ/δ agonist GW0742 and/or antagonist GSK0660 in vivo and hearts were subjected to ex vivo global ischemia followed by reperfusion. PPARβ/δ activation improved left ventricular developed pressure recovery, reduced infarct size (IS) and incidence of reperfusion-induced ventricular arrhythmias while it also up-regulated superoxide dismutase 2, catalase and uncoupling protein 3 resulting in attenuation of oxidative stress as evidenced by the reduction in 4-hydroxy-2-nonenal protein adducts and protein carbonyl formation. PPARβ/δ activation also increased both mRNA expression and enzymatic activity of aldehyde dehydrogenase 2 (ALDH2); inhibition of ALDH2 abrogated the IS limiting effect of PPARβ/δ activation. Furthermore, upregulation of PGC-1α and isocitrate dehydrogenase 2 mRNA expression, increased citrate synthase activity as well as mitochondrial ATP content indicated improvement in mitochondrial content and energy production. These data provide new mechanistic insight into the cardioprotective properties of PPARβ/δ in I/R pointing to ALDH2 as a direct downstream target and suggesting that PPARβ/δ activation alleviates myocardial I/R injury through coordinated stimulation of the antioxidant defense of the heart and preservation of mitochondrial function.

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.

Abstract 193: Antithrombin Perfluorocarbon Nanoparticles Ameliorate Renal Injury Following Transient Warm Ischemia

2014 ◽  
Vol 34 (suppl_1) ◽  
Author(s):  
Chandu Vemuri ◽  
Junjie Chen ◽  
Rohun U Palekar ◽  
John S Allen ◽  
Xiaoxia Yang ◽  
...  
Keyword(s):  
Reperfusion Injury ◽  
Renal Injury ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Kidney Injury ◽  
Warm Ischemia ◽  
P Value ◽  
Sprague Dawley ◽  
Histologic Analysis ◽  
Microvascular Thrombosis

Objective: Thrombin mediated microvascular thrombosis plays a crucial role in the pathogenesis of acute renal reperfusion injury following transient ischemia. We hypothesize that anti-thrombin nanoparticles will ameliorate acute renal injury by inhibiting microvascular thrombosis. Methods: Adult, male Sprague Dawley rats were randomized into two groups of 5 to receive tail vein injections of saline or nanoparticles loaded with Phe[D]-Pro-Arg-Chloromethylketone (NP-PPACK). Immediately following injection, all animals underwent operative bilateral renal artery occlusion to create 45 minutes of warm ischemia, followed by restoration of renal blood flow. Blood samples were drawn daily and animals were euthanized on day 1 or 7 for histologic analysis of kidney injury (H&E, TUNEL and thrombin staining). Results: Histologic analysis of renal tissue revealed significant apoptosis, necrosis and thrombin accumulation 1 day after ischemia-reperfusion, confirming acute kidney injury. The peak creatinine (mg/dl) on day 1 was significantly lower in NP-PPACK treated animals (0.57 +/- 0.07 (SEM)) than in saline treated controls (1.40 +/- 0.20 (SEM); p-value <0.01). Furthermore, animals treated with NP-PPACK continued to exhibit less renal dysfunction for 7 days after injury (Figure 1). Conclusion: Histologically confirmed intrarenal thrombosis was detected one day after ischemia-reperfusion injury. Targeted inhibition of thrombin with NP-PPACK prevented a decline in renal function following transient occlusion. Future work will focus on defining the underlying mechanisms of this effect.

scholarly journals Ex vivo carbon monoxide prevents cytochrome P450 degradation and ischemia/reperfusion injury of kidney grafts

2008 ◽  
Vol 74 (8) ◽  
pp. 1009-1016 ◽  
Author(s):  
Atsunori Nakao ◽  
Gaetano Faleo ◽  
Hiroko Shimizu ◽  
Kiichi Nakahira ◽  
Junichi Kohmoto ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Cytochrome P450 ◽  
Reperfusion Injury ◽  
Ischemia Reperfusion Injury ◽  
Ex Vivo ◽  
Ischemia Reperfusion

scholarly journals Normothermic Ex-vivo Kidney Perfusion in a Porcine Auto-Transplantation Model Preserves the Expression of Key Mitochondrial Proteins: An Unbiased Proteomics Analysis

2020 ◽  
Author(s):  
Caitriona M. McEvoy ◽  
Sergi Clotet-Freixas ◽  
Tomas Tokar ◽  
Chiara Pastrello ◽  
Shelby Reid ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Ischemia Reperfusion Injury ◽  
Ex Vivo ◽  
Ischemia Reperfusion ◽  
Graft Function ◽  
Kidney Injury ◽  
Tca Cycle ◽  
Proteomics Analysis ◽  
Beneficial Effects ◽  
Kidney Perfusion

AbstractNormothermic ex-vivo kidney perfusion (NEVKP) results in significantly improved graft function in porcine auto-transplant models of DCD injury compared to static cold storage (SCS); however, the molecular mechanisms underlying these beneficial effects remain unclear. We performed an unbiased proteomics analysis of 28 kidney biopsies obtained at 3 time points from pig kidneys subjected to 30-minutes of warm ischemia, followed by 8 hours of NEVKP or SCS, and auto-transplantation. 70/6593 proteins quantified were differentially expressed between NEVKP and SCS groups (FDR<0.05). Proteins increased in NEVKP mediated key metabolic processes including fatty acid ß-oxidation, the TCA-cycle and oxidative phosphorylation. Comparison of our findings with external datasets of ischemia-reperfusion, and other models of kidney injury confirmed that 47 of our proteins represent a common signature of kidney injury reversed or attenuated by NEVKP. We validated key metabolic proteins (ETFB, CPT2) by immunoblotting. Transcription factor databases identified PPARGC1A, PPARA/G/D and RXRA/B as the upstream regulators of our dataset, and we confirmed their increased expression in NEVKP with RT-PCR. The proteome-level changes observed in NEVKP mediate critical metabolic pathways that may explain the improved graft function observed. These effects may be coordinated by PPAR-family transcription factors, and may represent novel therapeutic targets in ischemia-reperfusion injury.

scholarly journals mTOR‐mediated calcium transients affect cardiac function in ex vivo ischemia–reperfusion injury

2021 ◽  
Vol 9 (6) ◽  
Author(s):  
Briana K. Shimada ◽  
Naaiko Yorichika ◽  
Jason K. Higa ◽  
Yuichi Baba ◽  
Motoi Kobayashi ◽  
...  
Keyword(s):  
Cardiac Function ◽  
Reperfusion Injury ◽  
Ischemia Reperfusion Injury ◽  
Ex Vivo ◽  
Ischemia Reperfusion ◽  
Calcium Transients

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.

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