Abstract P34: Nitrite Therapy upon Resuscitation from Cardiac Arrest Reversibly Inhibits Mitochondrial Complex I Reducing ROS Burst and Improving Cardiac Function and Survival

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Cameron Dezfulian ◽  
Sruti Shiva ◽  
Akshay Pendyal ◽  
Aleksey Alekseyenko ◽  
Stasia A Anderson ◽  
...  
Keyword(s):  
Cardiac Arrest ◽  
Complex I ◽  
Myocardial Dysfunction ◽  
Cardiac Contractility ◽  
Respiratory Control ◽  
Chain Complex ◽  
Ros Generation ◽  
Atp Production ◽  
Amplex Red ◽  
Ros Burst

Nitrite reversibly S-nitrosates mitochondrial electron transport chain complex I (cxI) resulting in transient inhibition and reduction of pathological ROS burst after ischemia. We hypothesized that nitrite therapy at CPR initiation could thus improve cardiac contractility and mortality. Anesthetized C57BL/6 mice underwent hyperkalemic cardiac arrest maintained for 12min at 36.5C prior to randomly receiving blinded IV nitrite or saline placebo, epinephrine, chest compressions and ventilation for up to 150 sec. ROSC was obtained in excess of 90% in both groups. Hearts were excised just prior to asystole, 5 or 60 minutes after the initiation of CPR and mitochondria isolated. Respiration was assessed by oxygen consumption after providing the cxI substrate pyruvate or the complex II (cxII) substrate succinate. CxI activity was directly assayed by NADH oxidation, peroxide generation measured by Amplex Red peroxidation and ATP production quantified by luciferin luminescence. Nitrite therapy was associated with improved hemodynamics and significantly improved LVEF and RVEF (Table 1 ) and better 22h survival (HR 2.72 [95% CI:1.1– 6.7]). Nitrite significantly reduced cxI mediated respiration 5 min post-CPR with loss of inhibition by 60min based on respiration and ATP production (Table II ). Respiration efficiency (respiratory control ratio) did not change, nor was there significant cxII inhibition. Early cxI inhibition was associated with significantly less ROS. Nitrite therapy transiently and reversibly inhibits cxI reducing reperfusion ROS-mediated injury and resulting in less myocardial dysfunction and death after cardiac arrest. Myocardial dysfunction occurs after cardiac arrest and is reduced with nitrite therapy Nitrite therapy specifically and reversibly inhibits complex I and reduces ROS generation

Abstract 142: Combined Therapy with Polyethylene Glycol-20k and MCC950 Preserves Post-resuscitation Myocardial Mitochondrial Function in a Rat Model of Cardiac Arrest and Cardiopulmonary Resuscitation

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_4) ◽  
Author(s):  
Lian Liang ◽  
Guozhen Zhang ◽  
Hui Li ◽  
Cheng Cheng ◽  
Tao Jin ◽  
...  
Keyword(s):  
Cardiac Arrest ◽  
Polyethylene Glycol ◽  
Cardiopulmonary Resuscitation ◽  
Rat Model ◽  
Mitochondrial Function ◽  
Complex I ◽  
Myocardial Dysfunction ◽  
Combined Therapy ◽  
Chain Complex ◽  
Sprague Dawley

Introduction: Mitochondrial dysfunction from global ischemic-reperfusion (I/R) injury is a major contributor to post-resuscitation myocardial dysfunction. Polyethylene Glycol-20k (PEG-20k) shortens the no-flow phenomenon and improves microcirculation while MCC950 selectively inhibits activation of the NLRP3-inflammasome ensuing pyroptosis. We evaluated the effect of combined therapy with PEG-20k and MCC950 on myocardial mitochondrial function as measured by electron transport chain complex respiration in a rat model of cardiac arrest (CA) and cardiopulmonary resuscitation (CPR). Methods: 30 Sprague-Dawley rats weighing between 450-550 g were randomized into five groups (n=6): (1) sham (S); (2) control (C); (3) PEG-20k (P); (4) MCC950 (M); (5) combined (P&M). Ventricular fibrillation (VF) was electrically induced and untreated for 6min, followed by 8min CPR. Resuscitation was attempted with a 4J defibrillation. 2mL P was infused over 2 min at the beginning of CPR, while M (10mg/kg) was administered intraperitoneal (IP) immediately after return of spontaneous circulation (ROSC). At ROSC 6hr, 100mg of heart was harvested, transferred directly into ice-cold K medium (1mL), and homogenized to obtain a 10% homogenate. Homogenates (50μL) were transferred to calibrated Oxygraph-2 chambers. Mitochondrial function was measured using high resolution respirometry. Oxygen flux was corrected and expressed by tissue wet weight, pmol/(min*mg). Data were analyzed by one-way analysis of variance (one-way ANOVA) followed by Tukey’s post hoc test for comparisons between multiple groups. Results: Complex I respiration in C was compromised at ROSC 6hr compared to S (564.0±160.0 vs 2729.5±339.5, p<0.001). As expected, P and M restored complex I respiration (1224.4±328.6, p<0.001) and (1804.4±293.1, p<0.01) compared to C. P&M further consolidated Complex I respiration function recovery (2527.6±145.5). Conclusion: Combined Therapy with PEG-20k and MCC950 preserves post-resuscitation myocardial mitochondrial function in a rat model of CA and CPR.

Abstract 2630: Evidence of Early Heart Mitochondrial Dysfunction after Resuscitation from Cardiac Arrest

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Natalia A Riobo ◽  
Fei Han ◽  
Tong Da ◽  
Lance B Becker
Keyword(s):  
Cardiac Arrest ◽  
Cytochrome C ◽  
Mitochondrial Dysfunction ◽  
Complex I ◽  
Atp Synthesis ◽  
Spontaneous Circulation ◽  
Metabolic Dysfunction ◽  
Amplex Red ◽  
Production Of Hydrogen ◽  
Complex I Activity

Background: Reperfusion injury post-resuscitation is associated with metabolic dysfunction and free radicals production. It has been hypothesized that mitochondrial permeability changes induced by calcium overload underlies this uncoupling of respiration from ATP synthesis and initiates cytochrome c-dependent apoptotic cascades. Our goal is to evaluate the intrinsic status of the mitochondrial electron transfer chain, i.e. irreversible modifications, in resuscitated animals independently of transient changes in calcium and permeability. Methods: Female mice were subjected to 8 min cardiac arrest by KCl injection followed by mechanical ventilation and CPR until return of spontaneous circulation (resuscitation rate: 86%, 24 h survival: 40%) under continuous blood pressure and temperature monitoring. Animals were divided in 4 groups: SHAM (instrumented, no cardiac arrest), CA (8 min cardiac arrest), R30 (30 min post-resuscitation), and R60 (60 min post-resuscitation). Heart mitochondria were immediately isolated and physically disrupted to dissipate ionic gradients in the presence of a calcium chelator. Production of hydrogen peroxide (H 2 O 2 ) by Complex I and III was determined fluorometrically with the Amplex Red-HRP system and the activities of Complex I, II, and the Complex I-III and II-III segments by spectrophotometric techniques using appropriate substrates and inhibitors. Cytochrome c content and the COX IV subunit (as a loading control) were analyzed by western blot and densitometry. Results: A 40% increase in H 2 O 2 production by Complex I and III was evident after just 8 min of cardiac arrest (ECA group, p<0.05), which was followed by a progressive reduction in Complex I activity (ECA>R30>R60), resulting in a relative doubling of electron leak. In contrast, Complex II and II-III activities and cytochrome c content remained unaffected at all times evaluated. Conclusions: Using an animal model that closely mimics resuscitation in humans, we have found signs of early mitochondrial dysfunction independently of transient changes in permeability and calcium. These changes are consistent with increased ROS production at expense of impaired oxidative phosphorylation.

Abstract 217: Increased Oxidation of Amplex Red in Post-Cardiac Arrest Human and Rat Plasma Can Be Utilized as a Potential Marker of Injury Severity

Circulation ◽  
2019 ◽  
Vol 140 (Suppl_2) ◽  
Author(s):  
Muhammad Shoaib ◽  
Ann Iverson ◽  
Tai Yin ◽  
Lance B Becker ◽  
Junhwan KIM
Keyword(s):  
Hydrogen Peroxide ◽  
Cardiac Arrest ◽  
Injury Severity ◽  
Ischemia Reperfusion ◽  
University Hospital ◽  
Ros Generation ◽  
Ischemic Damage ◽  
Sprague Dawley ◽  
Amplex Red ◽  
Potential Marker

Introduction: Cardiac arrest (CA), an unexpected loss of appropriate electrical signaling in the heart, leads to a loss of blood circulation and decreased oxygen perfusion. Ischemia results in the generation of hydrogen peroxide and other reactive oxygen species (ROS), thereby causing damage to tissues. Currently, there are no available biomarkers to elucidate the severity of ischemic damage. Therefore, oxidation of the Amplex Red (AR) assay by ROS into its fluorescent product, resorufin, may be used as a marker to determine injury severity. Methods: Plasma isolated from human CA patients from North Shore University Hospital was obtained to determine ROS generation. A commercially available Amplex Red assay kit was used to measure the amount of resorufin produced after oxidation due to hydrogen peroxide, peroxynitrite, and other ROS. To verify our human findings, we arbitrarily assigned adult male Sprague-Dawley rats into three groups (control, 10 min cardiac arrest, and 20 min cardiac arrest) using our reliable asphyxia-induced cardiac arrest model. Results: Despite human variations, our data on human CA patients showed an increased amount of AR oxidation as a result of ischemia. Our 10 min CA rat experimental model verified that Amplex Red is capable of detecting hydrogen peroxide and peroxynitrite formation after ischemia. Rats with 20 mins of ischemia time also produced resorufin, confirming that ischemia induces AR oxidation. Removing horseradish peroxidase and adding catalase controls for hydrogen peroxide and peroxynitrite, which should decrease AR oxidation; however, we observed an increase in AR oxidation. Therefore, we added phenylmethyl sulfonyl acid (PMSF), an inhibitor of carboxylesterase, an enzyme also capable of oxidizing Amplex Red, which resulted in decreased AR oxidation. Conclusion: By accounting for peroxide and peroxynitrite species, the increase in Amplex Red oxidation in the plasma of cardiac arrest human patients and rats can be attributed to carboxylesterase activity. Our data corroborates the various mechanisms of AR oxidation in the setting of ischemia-reperfusion allowing the Amplex Red assay to be utilized as a potential tool for assessing the degree of ischemic damage resulting from cardiac arrest.

Abstract 71: The Effect of Achieving Return of Spontaneous Circulation on Mitochondrial Respiration Following Prolonged Cardiac Arrest

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Timothy R Matsuura ◽  
Jason A Bartos ◽  
Guillaume Debaty ◽  
Scott H McKnite ◽  
Jennifer N Rees ◽  
...  
Keyword(s):  
Cardiac Arrest ◽  
Mitochondrial Respiration ◽  
Complex I ◽  
Respiratory Control ◽  
Pulseless Electrical Activity ◽  
Spontaneous Circulation ◽  
P Value ◽  
Ischemia And Reperfusion Injury ◽  
Return Of Spontaneous Circulation ◽  
Complex Ii

Introduction: Ischemia and reperfusion injury have been shown to alter mitochondrial function. Respiration, a primary function of mitochondria and marker of mitochondrial health, was previously believed to be unrecoverable after prolonged cardiac arrest. We investigated the effect that return of spontaneous circulation (ROSC) has on the mitochondrial respiratory profile of the myocardium. Methods: After 15 minutes of untreated ventricular fibrillation (VF), 16 pigs received mechanical CPR and intravenous epinephrine per standard AHA protocols. Defibrillation was first attempted after 4 minutes of CPR. In the event of persistent VF or pulseless electrical activity, CPR was continued for up to 15 minutes with epinephrine and defibrillations administered every 3 minutes. Animals that had ROSC were sacrificed 15 minutes after the initiation of resuscitation efforts. Another 6 animals were used as non-ischemic controls and had no cardiac arrest. Cardiac mitochondria were isolated. Respiration for complex I and complex II substrates was measured. Respiratory control index (RCI) was calculated as the ratio of state 3 to state 4 respiration. Mean RCI were compared via t-test and ANOVA. A p-value of < 0.05 was considered significant. Results: ROSC was achieved in 10 of 16 animals. Fifteen minutes after initiation of resuscitation efforts, animals that achieved ROSC had significantly higher complex I RCI compared to animals with ongoing CPR (8.0±0.8 vs. 4.3±0.4, p<0.01). Complex I RCI in animals that achieved ROSC recovered to that of non-ischemic controls (8.0±0.8 vs. 6.3±0.5, p=0.17). Complex II RCI did not differ between ROSC, CPR, and non-ischemic controls (3.2±0.3 vs. 2.7 ±0.2 vs. 3.2±0.1, respectively; p=0.40). Conclusion: Achieving ROSC after prolonged untreated cardiac arrest leads to normalization of mitochondrial respiration within 15 minutes of the initiation of resuscitation efforts. At the same time, complex I RCI is suppressed and complex II RCI is unaffected during ongoing CPR. Decreased mitochondrial complex I respiration during ongoing CPR could be the cause or the effect of the absence of ROSC. Further investigation is needed.

Mitochondrial performance in heat acclimation—a lesson from ischemia/reperfusion and calcium overload insults in the heart

2012 ◽  
Vol 303 (8) ◽  
pp. R870-R881 ◽  
Author(s):  
Miri Assayag ◽  
Ann Saada ◽  
Gary Gerstenblith ◽  
Haifa Canaana ◽  
Rivka Shlomai ◽  
...  
Keyword(s):  
Mitochondrial Biogenesis ◽  
Respiratory Function ◽  
Complex I ◽  
Ischemia Reperfusion ◽  
Membrane Integrity ◽  
Chain Complex ◽  
Heat Acclimation ◽  
Cross Tolerance ◽  
Atp Production ◽  
Hypoxia Reoxygenation

Long-term heat acclimation (LTHA; 30 days, 34°C) causes phenotypic adaptations that render protection against ischemic/reperfusion insult (I/R, 30 min global ischemia and 40 min reperfusion) via heat acclimation-mediated cross-tolerance (HACT) mechanisms. Short-term acclimation (STHA, 2 days, 34°C), in contrast, is characterized by cellular perturbations, leading to increased susceptibility to insults. Here, we tested the hypothesis that enhanced mitochondrial respiratory function is part of the acclimatory repertoire and that the 30-day regimen is required for protection via HACT. We subjected isolated hearts and mitochondria from controls (C), STHA, or LTHA rats to I/R, hypoxia/reoxygenation, or Ca2+ overload insults. Mitochondrial function was assessed by measuring O2 consumption, membrane potential (ΔΨm), mitochondrial Ca2+ ([Ca2+]m), ATP production, respiratory chain complex activities, and molecular markers of mitochondrial biogenesis. Our results, combining physiological and biochemical parameters, confirmed that mitochondria from LTHA rats subjected to insults, in contrast to C, preserve respiratory functions (e.g., upon I/R, C mitochondria fueled by glutamate-malate, demonstrated decreases of 81%, 13%, 25%, and 50% in O2/P ratio, ATP production, ΔΨm, and complex I activity, respectively, whereas the corresponding LTHA parameters remained unchanged). STHA mitochondria maintained ΔΨm but did not preserve ATP production. LTHA [Ca2+]m was significantly higher than that of C and STHA and was not affected by the hypoxia/reoxygenation protocol compared with C. Enhanced mitochondrial biogenesis markers, switched-on during STHA coincidentally with enhanced membrane integrity (ΔΨm), were insufficient to confer intact respiratory function upon insult. LTHA was required for respiratory complex I adaptation and HACT. Stabilized higher basal [Ca2+]m and attenuated Ca2+ overload are likely connected to this adaptation.

scholarly journals The Hormetic Effect of Metformin: “Less Is More”?

2021 ◽  
Vol 22 (12) ◽  
pp. 6297
Author(s):  
Isabella Panfoli ◽  
Alessandra Puddu ◽  
Nadia Bertola ◽  
Silvia Ravera ◽  
Davide Maggi
Keyword(s):  
Complex I ◽  
Molecular Mechanisms ◽  
Hepatic Glucose Production ◽  
Glucose Production ◽  
Target Tissue ◽  
Atp Production ◽  
Less Is More ◽  
First Line Therapy ◽  
Hormetic Effect ◽  
Intracellular Content

Metformin (MTF) is the first-line therapy for type 2 diabetes (T2DM). The euglycemic effect of MTF is due to the inhibition of hepatic glucose production. Literature reports that the principal molecular mechanism of MTF is the activation of 5′-AMP-activated protein kinase (AMPK) due to the decrement of ATP intracellular content consequent to the inhibition of Complex I, although this effect is obtained only at millimolar concentrations. Conversely, micromolar MTF seems to activate the mitochondrial electron transport chain, increasing ATP production and limiting oxidative stress. This evidence sustains the idea that MTF exerts a hormetic effect based on its concentration in the target tissue. Therefore, in this review we describe the effects of MTF on T2DM on the principal target organs, such as liver, gut, adipose tissue, endothelium, heart, and skeletal muscle. In particular, data indicate that all organs, except the gut, accumulate MTF in the micromolar range when administered in therapeutic doses, unmasking molecular mechanisms that do not depend on Complex I inhibition.

ERYTHROPOIETIN IMPROVES THE POSTRESUSCITATION MYOCARDIAL DYSFUNCTION AND SURVIVAL IN THE ASPHYXIA-INDUCED CARDIAC ARREST MODEL

Shock ◽  
2007 ◽  
Vol 28 (1) ◽  
pp. 53-58 ◽  
Author(s):  
Chien-Hua Huang ◽  
Chiung-Yuan Hsu ◽  
Huei-Wen Chen ◽  
Min-Shan Tsai ◽  
Hsiao-Ju Cheng ◽  
...  
Keyword(s):  
Cardiac Arrest ◽  
Myocardial Dysfunction ◽  
Induced Cardiac Arrest
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