Min Of Cardiac Arrest Research Articles

Abstract 208: MicroRNA 122 and 300 as a Potential Prognosticator of Brain, Kidney and Liver Damage in Response to Ischemic-reperfusion Injury After Severe Rodent Cardiac Arrest

Introduction: Cardiac arrest (CA) causes ischemia and reperfusion damage to the entire body. Augmented expression of circulating microRNA (miR)-122 has been associated with poor neurological outcome after CA, as well as drug and alcohol-induced liver injury in human. Plasma exosomal miR-300 has shown to be up regulated in transient ischemic attack while cellular miR-300 expression increased after traumatic brain injury in rodent model. Hypothesis: The response of tissue injury can be determined by measuring differential expression of miR. This study sought to quantify two specific miR-122 and 300, from the intracellular compartment of the brain, kidney, and liver tissues to determine the injury pattern after severe CA and resuscitation. Methods: Male Sprague-Dawley rats were assigned into 2 groups: control (no CA or CA and resuscitation) and 20 min CA followed by 30 min cardiopulmonary bypass (CPB) resuscitation (n=3). Brain, kidney, and liver tissues were isolated and homogenized. Total RNA was isolated from homogenized tissue by trizol method, RNA was then converted to cDNA by RT kit and processed for miR-122 and miR-300 quantification using quantitative real-time polymerase chain reaction (qRT-PCR). RNU6 was used as an endogenous control and results were expressed in fold change. Results: Brain after CA and resuscitation revealed an increased trend in expression of miR-122 (p=0.053) and miR-300 (p=0.57). Liver also demonstrated an increasing trend in miR-122 (p=0.15) and miR-300 (p=0.007) expression. The increasing trend of miR-122 and miR-300 expression in brain and liver following CA and resuscitation suggests reperfusion injury in the early phase of resuscitation. Kidney demonstrated a lower expression of both miR-122 and miR-300 after CA and resuscitation, which suggests that the event of CA and resuscitation further down regulate miR-122 and miR-300 expression. Conclusion: Levels of intracellular miR-122 and 300 in the brain, kidney, and liver appear to be altered after CA and resuscitation. Although, only one of the miR showed a significant difference in our small exploratory study, the current finding suggests that tissue specific miR levels may provide insight about specific injury following CA.

Abstract 359: Systemic Administration of Allogeneic Mesenchymal Stem Cells Attenuates Post-Resuscitation Left Ventricular Dysfunction in a Porcine Model of Cardiac Arrest

Introduction: Advances in CPR have increased the likelihood of achieving ROSC after cardiac arrest (CA), but >50% of initially resuscitated patients die before hospital discharge. Evidence that a systemic inflammatory response exacerbates post-ROSC injury supports investigation of anti-inflammatory therapies in this setting. Accordingly, we tested the efficacy of allogeneic mesenchymal stem cell (MSC) administration early after ROSC in a porcine model of CA. Methods: Swine (n=33) were subjected to 10 min CA followed by mechanical CPR with defibrillation and intravenous epinephrine (EPI; 0.015 mg/kg). Animals that achieved ROSC (n=19) were blindly randomized to intraventricular saline (n=9) or allogeneic bone marrow-derived MSCs (55±2 x 10 6 ; n=10) 30 min post-ROSC. Intravenous EPI was given during the post-ROSC period as needed to maintain MAP ≥60 mmHg. Left ventricular (LV) function and plasma cardiac troponin I (cTnI) were assessed for 4 hr post-ROSC, at which time heart tissue was collected to assess myocardial inflammation (RT-PCR). Results: Compared with saline-treated controls, MSC-treated animals exhibited improved post-ROSC LV wall thickening ( A ) and lower cTnI levels, indicative of reduced myocardial injury. By design, both groups had a similar post-ROSC MAP and cardiac output, but the saline group required significantly more EPI ( B ). Although a similar degree of monocyte infiltration (CCR2) and macrophage expansion (CD68) was observed in both groups, MSCs increased expression of the anti-inflammatory marker Arginase1 ( C ) and tended to attenuate the post-ROSC rise in circulating IL-6 ( D ). Conclusion: Early post-ROSC delivery of allogeneic MSCs attenuates LV dysfunction and reduces the need for pharmacologic hemodynamic support after CA in swine. These results indicate that systemic MSC administration may be an effective immunomodulatory strategy to reduce post-resuscitation injury, particularly if protective effects extend to the brain.

Plasma metabolomics supports the use of long-duration cardiac arrest rodent model to study human disease by demonstrating similar metabolic alterations

Cardiac arrest (CA) is a leading cause of death and there is a necessity for animal models that accurately represent human injury severity. We evaluated a rat model of severe CA injury by comparing plasma metabolic alterations to human patients. Plasma was obtained from adult human control and CA patients post-resuscitation, and from male Sprague–Dawley rats at baseline and after 20 min CA followed by 30 min cardiopulmonary bypass resuscitation. An untargeted metabolomics evaluation using UPLC-QTOF-MS/MS was performed for plasma metabolome comparison. Here we show the metabolic commonality between humans and our severe injury rat model, highlighting significant metabolic dysfunction as seen by similar alterations in (1) TCA cycle metabolites, (2) tryptophan and kynurenic acid metabolites, and (3) acylcarnitine, fatty acid, and phospholipid metabolites. With substantial interspecies metabolic similarity in post-resuscitation plasma, our long duration CA rat model metabolically replicates human disease and is a suitable model for translational CA research.

Motor Cortex and Hippocampus Display Decreased Heme Oxygenase Activity 2 Weeks After Ventricular Fibrillation Cardiac Arrest in Rats.

Heme oxygenase (HO) and biliverdin reductase (BVR) activities are important for neuronal function and redox homeostasis. Resuscitation from cardiac arrest (CA) frequently results in neuronal injury and delayed neurodegeneration that typically affect vulnerable brain regions, primarily hippocampus (Hc) and motor cortex (mC), but occasionally also striatum and cerebellum. We questioned whether these delayed effects are associated with changes of the HO/BVR system. We therefore analyzed the activities of HO and BVR in the brain regions Hc, mC, striatum and cerebellum of rats subjected to ventricular fibrillation CA (6 min or 8 min) after 2 weeks following resuscitation, or sham operation. From all investigated regions, only Hc and mC showed significantly decreased HO activities, while BVR activity was not affected. In order to find an explanation for the changed HO activity, we analyzed protein abundance and mRNA expression levels of HO-1, the inducible, and HO-2, the constitutively expressed isoform, in the affected regions. In both regions we found a tendency for a decreased immunoreactivity of HO-2 using immunoblots and immunohistochemistry. Additionally, we investigated the histological appearance and the expression of markers indicative for activation of microglia [tumor necrosis factor receptor type I (TNFR1) mRNA and immunoreactivity for ionized calcium-binding adapter molecule 1 (Iba1])], and activation of astrocytes [immunoreactivity for glial fibrillary acidic protein (GFAP)] in Hc and mC. Morphological changes were detected only in Hc displaying loss of neurons in the cornu ammonis 1 (CA1) region, which was most pronounced in the 8 min CA group. In this region also markers indicating inflammation and activation of pro-death pathways (expression of HO-1 and TNFR1 mRNA, as well as Iba1 and GFAP immunoreactivity) were upregulated. Since HO products are relevant for maintaining neuronal function, our data suggest that neurodegenerative processes following CA may be associated with a decreased capacity to convert heme into HO products in particularly vulnerable brain regions.

The Effects of Dexmedetomidine Post-Conditioning on Cardiac and Neurological Outcomes After Cardiac Arrest and Resuscitation in Swine.

One of the main contents of post-resuscitation care is to alleviate cardiac and neurological damage in cardiac arrest (CA) victims. Recently, dexmedetomidine pre- and post-conditioning have been shown to both effectively protect the heart and brain against regional ischemia reperfusion injury. In this study, we investigated the effects of dexmedetomidine post-conditioning on cardiac and neurological outcomes after CA and resuscitation in swine. A total of 28 male domestic swine were randomized into four groups: sham, cardiopulmonary resuscitation (CPR), low-dose dexmedetomidine post-conditioning (LDP), and high-dose dexmedetomidine post-conditioning (HDP). Sham animals underwent the surgical preparation only. The animal model was established by 8 min of CA and then 5 min of CPR. After the animal was successfully resuscitated, a loading dose of 0.25 μg/kg of dexmedetomidine was intravenously injected followed by continuous infusion of 0.25 μg/kg/h for 6 h in the LDP group, and meanwhile a double dose of dexmedetomidine was similarly administered in the HDP group. The same amount of saline was given in the other two groups. All the resuscitated animals were monitored for 6 h and then returned to their cages for an additional 18 h of observation. After resuscitation, significantly greater cardiac, neurological dysfunction, and injuries were observed in all animals experiencing CA and resuscitation when compared with the sham group. However, the severity of cardiac and neurological damage was significantly milder in the two dexmedetomidine-treated groups than in the CPR group. Dexmedetomidine post-conditioning also significantly decreased post-resuscitation tissue inflammation, oxidative stress, and cell apoptosis and necroptosis in the heart and brain when compared with the CPR group. In addition, these protective effects produced by dexmedetomidine post-conditioning were significantly greater in the HDP group than in the LDP group. Dexmedetomidine post-conditioning dose-dependently improved post-resuscitation cardiac and neurological outcomes through the inhibition of tissue inflammation, oxidative stress, and cell apoptosis and necroptosis.

Protection from systemic pyruvate at resuscitation in newborn lambs with asphyxial cardiac arrest.

BackgroundInfants with hypoxic‐ischemic injury often require cardiopulmonary resuscitation. Mitochondrial failure to generate adenosine triphosphate (ATP) during hypoxic‐ischemic reperfusion injury contributes to cellular damage. Current postnatal strategies to improve outcome in hypoxic‐ischemic injury need sophisticated equipment to perform servo‐controlled cooling. Administration of intravenous pyruvate, an antioxidant with favorable effects on mitochondrial bioenergetics, is a simple intervention that can have a global impact. We hypothesize that the administration of pyruvate following the return of spontaneous circulation (ROSC) would improve cardiac function, systemic hemodynamics, and oxygen utilization in the brain in newborn lambs with cardiac arrest (CA).MethodsTerm lambs were instrumented, delivered by C‐section and asphyxia induced by umbilical cord occlusion along with clamping of the endotracheal tube until asystole; Lambs resuscitated following 5 min of CA; upon ROSC, lambs were randomized to receive pyruvate or saline infusion over 90 min and ventilated for 150 min postinfusion. Pulmonary and systemic hemodynamics and arterial gases monitored. We measured plasma pyruvate, tissue lactate, and ATP levels (heart and brain) in both groups.ResultsTime to ROSC was not different between the two groups. Systolic and diastolic blood pressures, stroke volume, arterial oxygen content, and cerebral oxygen delivery were similar between the two groups. The cerebral metabolic rate of oxygen was higher following pyruvate infusion; higher oxygen consumption in the brain was associated with lower plasma levels but higher brain ATP levels compared to the saline group.ConclusionsPyruvate promotes energy generation accompanied by efficient oxygen utilization in the brain and may facilitate additional neuroprotection in the presence of hypoxic‐ischemic injury.

Epinephrine Exacerbates Myocyte Injury in a Porcine Model of Cardiac Arrest

ObjectiveAlthough circulating cardiac troponin (cTn) concentrations are often elevated in patients following resuscitation from cardiac arrest (CA), this finding is commonly attributed to myocyte injury caused by ongoing myocardial infarction (MI) and/or defibrillation during resuscitation. To determine whether measurable cTn elevations occur independently of these factors, we employed serial sampling of systemic and coronary venous blood to quantify cTn release in a porcine model of CA devoid of ongoing MI or multiple defibrillation attempts. In light of recent concerns regarding potential detrimental effects of epinephrine (EPI) in CA, cTn levels were compared in animals that were resuscitated with vs. without exogenous EPI.MethodsSwine (n=41) were subjected to 7 min CA via electrical induction of ventricular fibrillation (VF) followed by cardiopulmonary resuscitation (CPR) with manual chest compressions and mechanical ventilation for up to 20 min. Biphasic defibrillation (200 J) was performed 1 min after the start of CPR and a subset of animals (n=10) received intravenous EPI (0.015 mg/kg) 1 min later. After return of spontaneous circulation (ROSC; defined as unassisted systolic blood pressure >80 mmHg for 1 min), animals were followed for up to 4 hours with serial blood sampling from the jugular vein and coronary sinus for assessment of cTnI via a porcine‐specific ELISA.ResultsAmong the entire cohort, 1.2±0.1 defibrillator shocks were required to terminate VF, ROSC was achieved 175±7 seconds after the initiation of CPR, and 15 animals (38%) survived for the entire 4‐hour recovery period (2/10 with EPI, 13/31 without EPI). Despite the absence of ongoing MI or prolonged resuscitation efforts, a significant 5‐fold rise in coronary sinus (from 106±17 to 526±74 ng/L, p<0.01) and systemic (from 67±14 to 350±54 ng/L, p<0.01) cTnI concentrations was observed 15 min post‐ROSC (trans‐coronary cTnI gradient from 39±7 to 176±29 ng/L, p<0.01). Widening of the trans‐coronary cTnI gradient continued throughout the recovery period, reaching 795±164 ng/L 4 hours post‐ROSC and leading to a 16‐fold increase in circulating cTnI concentrations at this timepoint (1087±208 ng/L, p<0.01 vs. baseline). Exogenous EPI exacerbated myocyte injury, as EPI‐treated animals exhibited a significantly higher trans‐coronary cTnI gradient 30 min post‐ROSC that persisted throughout the recovery period and led to significantly higher circulating cTnI concentrations vs. animals resuscitated without EPI at each timepoint (Figure ).ConclusionsThese results demonstrate that resuscitation from CA is associated with measurable elevations in cTnI as early as 15 min post‐ROSC, even in the absence of ongoing MI or prolonged CPR with multiple defibrillator shocks. Thus, assessment of circulating cTnI following resuscitation from CA is unlikely to accurately identify patients suffering from an acute coronary syndrome. Administration of exogenous EPI during resuscitation exacerbates the extent of myocyte injury, which may contribute to poor long‐term outcomes.Support or Funding InformationFunding SourcesNIH, AHA, ZOLL Foundation, Pro‐Al Medico Technologies, Inc., UB CAT, NCATS, and the Dept. of Veterans Affairs.Figure 1

Neuroprotective Effect of the Inhibitor Salubrinal after Cardiac Arrest in a Rodent Model.

Cardiac arrest (CA) yields poor neurological outcomes. Salubrinal (Sal), an endoplasmic reticulum (ER) stress inhibitor, has been shown to have neuroprotective effects in both in vivo and in vitro brain injury models. This study investigated the neuroprotective mechanisms of Sal in postresuscitation brain damage in a rodent model of CA. In the present study, rats were subjected to 6 min of CA and then successfully resuscitated. Either Sal (1 mg/kg) or vehicle (DMSO) was injected blindly 30 min before the induction of CA. Neurological status was assessed 24 h after CA, and the cortex was collected for analysis. As a result, we observed that, compared with the vehicle-treated animals, the rats pretreated with Sal exhibited markedly improved neurological performance and cortical mitochondrial morphology 24 h after CA. Moreover, Sal pretreatment was associated with the following: (1) upregulation of superoxide dismutase activity and a reduction in maleic dialdehyde content; (2) preserved mitochondrial membrane potential; (3) amelioration of the abnormal distribution of cytochrome C; and (4) an increased Bcl-2/Bax ratio, decreased cleaved caspase 3 upregulation, and enhanced HIF-1α expression. Our findings suggested that Sal treatment improved neurological dysfunction 24 h after CPR (cardiopulmonary resuscitation), possibly through mitochondrial preservation and stabilizing the structure of HIF-1α.

Edaravone Ameliorates Renal Warm Ischemia-Reperfusion Injury by Downregulating Endoplasmic Reticulum Stress in a Rat Resuscitation Model.

BackgroundThis study was conducted to explore whether the effect of edaravone (5-methyl-2-phenyl-2,4-dihydro-3H-pyrazol3-one, EDR) can ameliorate renal warm ischemia-reperfusion injury (IRI) by modulating endoplasmic reticulum stress (ERS) and its downstream effector after cardiac arrest (CA) and cardiopulmonary resuscitation (CPR) in a rat model.MethodsThe rats (n=10) experienced anaesthesia and intubation followed by no CA inducement were defined as the Sham group. Transoesophageal alternating current stimulation was employed to establish 8 min of CA followed by conventional CPR for a resuscitation model. The rats with successful restoration of spontaneous circulation (ROSC) randomly received EDR (3 mg/kg, EDR group, n=10) or equal volume normal saline solution (the NS group, n=10). At 24 hr after ROSC, serum creatinine (SCR), blood urea nitrogen (BUN) levels, and cystatin-C (Cys-C) levels were determined and the protein level of glucose-regulated protein (GRP78), C/EBP homologous protein (CHOP), extracellular signal-regulated kinase (ERK), phosphorylated extracellular signal-regulated kinase 1/2 (p-ERK1/2), Bax/Bcl-2, and caspase-3 were detected by Western blot method.ResultsAt 24 hrs after ROSC, SCR, BUN and Cys-C were obviously increased and the proteins expression, including GRP78, CHOP and p-ERK1/2, cleaved-caspase 3 Bax/Bcl-2 ratio, were significantly upregulated in the NS group compared with the Sham group (p<0.05). The remarkable improvement of these adverse outcomes was observed in the EDR group (p<0.05).ConclusionIn conclusion, we found that EDR ameliorates renal warm IRI by downregulating ERS and its downstream effectors in a rat AKI model evoked by CA/CPR. These data may provide evidence for future therapeutic benefits of EDR against AKI induced by CA/CPR.

Abstract 265: Deterioration of Hemodynamic Support During Prolonged Mechanical CPR in a Porcine Model of Cardiac Arrest

Introduction: Although mechanical CPR devices provide automated delivery of fixed depth chest compressions, the consistency of hemodynamic support during prolonged resuscitation efforts is unclear, particularly in the absence of concomitant vasopressor treatment. In light of recent concerns regarding potentially harmful effects of epinephrine, we evaluated the hemodynamic support generated by 20 min of mechanical CPR without concurrent vasopressor administration in a porcine model of cardiac arrest (CA). Methods: Swine (n=10) were subjected to 7-8 min of CA following electrical induction of ventricular fibrillation. CPR was subsequently performed for 20 min using a mechanical compression system (LUCAS 3.1, Stryker) programmed to administer 102 compressions/min at a fixed depth of 2.1 inches. Aortic pressure (Ao), coronary perfusion pressure (CPP), and cerebral oxygen saturation (rSO 2 ; near-infrared spectroscopy) were continuously recorded. Results were compared to a separate group of swine (n=11) that received manual CPR with a compression rate of 100/min and depth necessary to achieve peak Ao of 100 mmHg. Results: Initially, mechanical CPR generated significantly higher peak Ao and CPP vs. manual CPR ( Figure ). However, by 4 min CPR, peak Ao and CPP were no longer different between groups. Both parameters continued to decline in the mechanical CPR group but remained stable in animals receiving manual CPR. Cerebral rSO 2 values fell from 57±2 % at baseline to 42±4 % during CA (p&lt;0.01) but were not significantly improved by mechanical or manual CPR. Conclusion: The superior hemodynamic support initially offered by mechanical CPR deteriorates during prolonged CPR when pharmacologic vasopressor support is absent. These results demonstrate that a fixed compression depth does not necessarily produce consistent hemodynamic support and suggest that concomitant vasopressor administration may be necessary to sustain Ao and CPP during prolonged mechanical CPR.

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

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.

Biomechanical properties of the hypoxic and dying brain quantified by magnetic resonance elastography

Respiratory arrest is a major life-threatening condition leading to cessation of vital functions and hypoxic-anoxic injury of the brain. The progressive structural tissue changes characterizing the dying brain biophysically are unknown. Here we use noninvasive magnetic resonance elastography to show that biomechanical tissue properties are highly sensitive to alterations in the brain in the critical period before death. Our findings demonstrate that brain stiffness increases after respiratory arrest even when cardiac function is still preserved. Within 5 min of cardiac arrest, cerebral stiffness further increases by up to 30%. This early mechanical signature of the dying brain can be explained by water accumulation and redistribution from extracellular spaces into cells. These processes, together, increase interstitial and intracellular pressure as revealed by magnetic resonance spectroscopy and diffusion-weighted imaging. Our data suggest that the fast response of cerebral stiffness to respiratory arrest enables the monitoring of life-threatening brain pathology using noninvasive in vivo imaging. Statement of significanceHypoxia-anoxia is a life-threatening condition eventually leading to brain death. Therefore, monitoring vital brain functions in patients at risk is urgently required during emergency care or treatment of acute brain damage due to insufficient oxygen supply. In mouse model of hypoxia-anoxia, we have shown for the first time that biophysical tissue parameters such as brain stiffness changed markedly during the process of death.

Therapeutic Hypothermia After Cardiac Arrest: Involvement of the Risk Pathway in Mitochondrial PTP-Mediated Neuroprotection.

Therapeutic hypothermia is neuroprotective after cardiac arrest (CA) via poorly understood mechanisms. It may prevent mitochondrial permeability transition pore (PTP) opening, an event which plays a pivotal role in ischemia-reperfusion injury. PTP is the main end-effector of the reperfusion injury salvage kinase (RISK) signaling pathway. We hypothesized that therapeutic hypothermia activates the RISK pathway, thereby preventing PTP opening and its deleterious neurological consequences after CA. Four groups of New Zealand White rabbits were subjected to 15 min of CA and 120 min of reperfusion: Control, HT (hypothermia at 32°-34°C), NIM (specific PTP inhibition with N-methyl-4-isoleucine-cyclosporine at the onset of reperfusion), and HT+NIM. A Sham group only underwent surgery. The following measurements were taken: pupillary reflexes and brain damage biomarkers (NSE and S100β), RISK pathway activation in brain cortex (total and phosphorylated forms of both protein kinase B [Akt] and extracellular signal-regulated kinase [ERK]) and PTP opening in isolated brain mitochondria. Therapeutic hypothermia and pharmacological PTP inhibition preserved the pupillary reflexes and prevented the increase in both NSE and S100β (P < 0.05 vs. controls). These two interventions also enhanced (P < 0.05 vs. controls) the phospho-Akt/Akt ratio to a similar extent while preventing a CA-induced increase in phospho-ERK/ERK ratio. This Akt activation in the HT and NIM groups was associated with an attenuation of CA-induced PTP opening. In this model, therapeutic hypothermia promoted the activation of the RISK signaling pathway via Akt and limited CA-induced brain injury by preventing PTP opening.

Protective effects of ghrelin on brain mitochondria after cardiac arrest and resuscitation

Mitochondrial dysfunction plays a critical role in brain injury after cardiac arrest (CA) and cardiopulmonary resuscitation (CPR). Our recent study demonstrated that ghrelin protected against post-resuscitation brain injury with an elevated expression of mitochondrial uncoupling protein 2 (UCP2). However, the effects of ghrelin on mitochondrial dysfunction after CA are not clear. In the present study, the protective role of ghrelin was evaluated on mitochondrial dysfunction and the subsequent damage induced by CA in rats. In addition, mitochondrial unfolded protein response (UPRmt), an intrinsic cytoprotective pathway, was observed at the same time. Either vehicle (saline) or ghrelin (80 μg/kg) was injected blindly immediately after 6 min of CA and successful resuscitation. Neurological deficit was evaluated 6 h after CA and then cortex was collected for assessments. As a result, we found that ghrelin significantly improved the neurological deficit score in rats after CA. The functional analysis of isolated mitochondria revealed that ghrelin improved the mitochondrial ATP synthesis capacity and significantly reduced the reactive oxygen species (ROS) leakage after 6 h of CA. Concomitantly, we observed an increased ATP level and an attenuated oxidative stress in ghrelin treated animals. Moreover, ghrelin markedly improved the mitochondrial morphology compared with the vehicle animals. Further research revealed that ghrelin treatment significantly activated the UPRmt as demonstrated by the increased expression of heat shock protein 60 (HSP60), heat shock protein 10 (HSP10), caseinolytic protease 1 (CLPP1), and high-temperature requirement protein A2 (HTRA2). Our results suggest that ghrelin protected against cerebral mitochondria dysfunction after CA and the mechanism may involve a UPRmt pathway.

Custodiol-N™ cardioplegia lowers cerebral inflammation and activation of hypoxia-inducible factor-1α.

Cardioplegic solutions induce cardiac arrest and protect cardiac tissue from ischaemia-reperfusion injury. However, the effects on the brain, which is vulnerable to cardiopulmonary bypass (CPB) surgery and ischaemia-reperfusion injury, mostly remain unknown. We investigated if cardioplegic solutions differ in their effects in altered oxygen conditions and in their ability to induce cerebral inflammation. Thirty pigs were subjected to a midline sternotomy and CPB at 34°C with 90 min cardiac arrest followed by 120 min reperfusion. Following randomization on a 1:1:1 basis, they received either a single shot of histidine-tryptophan-α-ketoglutarate (HTK)-Bretschneider solution (n = 10), histidine-tryptophan-α-ketoglutarate-N (HTK-N; n = 10) or HTK plus 1.2 mg/l cyclosporine A (HTK/CsA; n = 10). Brain regions of interest (frontal cortex, cerebellum, brain stem, diencephalon, colliculus superior) were analysed by real time quantitative reverse transcriptase polymerase chain reaction for hypoxia-inducible factor-1α (HIF-1α), tumour necrosis factor-α, interleukin (IL)-10, IL-1β and IL-1β receptor as well as by immunohistochemical analysis for HIF-1α. Blood gas and electrolyte analyses were performed. Comparisons between baseline and reperfusion period levels revealed that HTK-N cardioplegia induced a smaller reduction of the haemoglobin content and blood calcium concentrations (hbbaseline: 5.97 ± 0.63 mmol/l; hbreperfusion: 6.16 ± 0.66 mmol/l; P = 0.428; Cabaseline2+: 1.36 ± 0.05 mmol/l; Careperfusion2+: 1.28 ± 0.05 mmol/l; P < 0.001) compared to HTK (hbbaseline: 5.93 ± 0.45 mmol/l; hbreperfusion: 4.72 ± 0.79 mmol/l; P = 0.001; Cabaseline2+: 1.34 ± 0.07 mmol/l; Careperfusion2+: 1.24 ± 0.06 mmol/l; P = 0.004) and HTK/CsA cardioplegia (hbbaseline: 5.88 ± 0.44 mmol/l; hbreperfusion: 5.14 ± 0.87 mmol/l; P = 0.040; Cabaseline2+: 1.38 ± 0.04 mmol/l; Careperfusion2+: 1.20 ± 0.14 mmol/l; P = 0.001). Brain region-specific regulation of the HIF-1α expression, no general HIF-1α activation and a lower tumour necrosis factor-α expression (pto HTK = 0.050, pto HTK/CsA = 0.013) were documented for HTK-N cardioplegia. HTK-N (Custodiol-N) induced fewer cerebral effects and less inflammation during CPB surgery than HTK and HTK/CsA cardioplegia. These data suggest that HTK-N exerts brain protective effects during and after CPB surgery.

Palmitic acid methyl ester is a novel neuroprotective agent against cardiac arrest

We previously discovered that palmitic acid methyl ester (PAME) is a potent vasodilator first identified and released from the superior cervical ganglion and remain understudied. Thus, we investigated PAME's role in modulating cerebral blood flow (CBF) and neuroprotection after 6 min of cardiac arrest (model of global cerebral ischemia). Our results suggest that PAME can enhance CBF under normal physiological conditions, while administration of PAME (0.02 mg/kg) immediately after cardiopulmonary resuscitation can also enhance CBF in vivo. Additionally, functional learning and spatial memory assessments (via T-maze) 3 days after asphyxial cardiac arrest (ACA) suggest that PAME-treated rats have improved learning and memory recovery versus ACA alone. Furthermore, improved neuronal survival in the CA1 region of the hippocampus were observed in PAME-treated, ACA-induced rats. Altogether, our findings suggest that PAME can enhance CBF, alleviate neuronal cell death, and promote functional outcomes in the presence of ACA.

Single dose of 17β-estradiol provides transient neuroprotection in female juvenile mice after cardiac-arrest and cardiopulmonary resuscitation

Each year there are approximately 7000 out of hospital cardiac arrests in the pediatric population, with 30% resuscitation rate and a 6–10% rate of survival to hospital discharge. Survivors of cardiac arrest exhibit learning and memory deficits that are devastating during the school years. Delayed neuronal cell death occurs in the hippocampus following cardiac arrest and likely contributes to memory impairments. Circulating endogenous estrogen in young adult females has been shown to provide protection against ischemic cell death, as does chronic exogenous administration of 17β-estradiol (E2). Chronic estrogen benefit can have undesirable feminizing effects, particularly in pre-adolescents. Here, we tested if a single-dose of E2 is neuroprotective in our pediatric cardiac arrest mouse model performed in juvenile mice. We subjected P21P25 C57Blk6 male and female mice to 8 min of cardiac arrest followed by cardiopulmonary resuscitation (CA/CPR). This developmental stage preceded the hormonal onset and serum estradiol and testosterone levels were not different in males and females. A single dose of E2 (100μg/kg) or vehicle was administered 30 min after resuscitation. Neuronal cell death measured 3 days after CA/CPR showed reduced hippocampal cell death in E2-treated females, but not males. Benefit of E2 in females was blocked by the P38 MAPK inhibitor, SB203580. Hippocampal-dependent memory function was equally impaired in E2-and vehicle-treated females measured in the contextual fear conditioning task at 7 days. Our findings demonstrate female-specific transient neuroprotection with E2 that does not provide sustained functional benefit.

Abstract 359: Use of Resuscitative Balloon Occlusion of the Aorta in a Swine Model of Prolonged Cardiac Arrest

Introduction: Despite advancements in CPR, survival to hospital discharge remains low for in- and out-of-hospital cardiac arrest (CA). Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) is an evolving tool for temporary control of non-compressible truncal hemorrhage. In this investigation, we examined whether REBOA use during non-traumatic CA would produce favorable hemodynamic changes associated with return of spontaneous circulation (ROSC). Hypothesis: We hypothesized that REBOA use during CPR would result in higher coronary perfusion pressure (CPP) and common carotid artery blood flow (C-Flow) in a prolonged model of CA. Methods: Six male swine were anesthetized and instrumented to measure and monitor CPP, and C-Flow. A REBOA catheter (Prytime Medical Devices) was advanced into zone 1 of the aorta through the femoral artery. Ventricular fibrillation was electrically induced and untreated for 8 minutes. CPR was started manually at minute-8, then changed to mechanical CPR at minute-12 for the duration of the experiment. Continuous infusion of epinephrine (0.0024mg/kg/min) was simultaneously started with mechanical CPR. The REBOA balloon was inflated beginning at minute-16 for 3 minutes then deflated for 3 minutes for a total of 6 cycles. At the end of the final cycle (REBOA inflation), CPR was stopped (after 33 minutes of total arrest time) and animals were defibrillated using 200 J biphasic shocks, repeated up to 6 times. Animals achieving ROSC were monitored for an additional 25 minutes. Results: Analysis using repeated measure ANOVA showed significant differences between balloon deflation and inflation periods for CPP (p&lt;0.0001) with mean difference(SD) of 14(2.6) (Range: 17 to 42) mmHg and for C-Flow (p&lt;0.0001) with mean difference(SD) 16(23) (Range: 115 to 269) mL/min across all animals. Three animals achieved ROSC and had significantly higher CPP (48 vs. 24mmHg, p&lt;0.0001) and C-Flow (249 vs. 168mL/min) by t-test (p&lt;0.0001). Post-mortem aortic histology did not reveal any changes produced by balloon inflation. Conclusion: REBOA significantly increased CPP and C-Flow in this swine model of prolonged CA. These increases may have contributed to the ability to achieve ROSC after greater than 30 min of CA.

Inhibiting Succinate Dehydrogenase by Dimethyl Malonate Alleviates Brain Damage in a Rat Model of Cardiac Arrest

Brain damage is a leading cause of death in patients with cardiac arrest (CA). The accumulation of succinate during ischemia by succinate dehydrogenase (SDH) is an important mechanism of ischemia–reperfusion injury. It was unclear whether inhibiting the oxidation of accumulated succinate could also mitigate brain damage after CA. In this study, rats were subjected to a 6 min of CA, and cardiopulmonary resuscitation (CPR) was performed with administration of normal saline or dimethyl malonate (DMM, a competitive inhibitor of SDH). After the return of spontaneous circulation, neurological function of the rats was assessed by a tape removal test for 3 days. The rats were then sacrificed, and their brains were used to assess neuronal apoptosis by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay. Hippocampal tissues were used for Western blotting analysis and biochemical detection. In addition, hippocampal mitochondria during CA and CPR were isolated. The relative mitochondrial membrane potential (MMP) and cytochrome C in the cytosol were detected. Our results show that DMM promoted ROSC and neurological performance in rats after CA. The TUNEL assay showed that DMM reduced neuronal apoptosis. Western blotting analysis showed that DMM inhibited the activation of caspase-3 and enhanced the expression of HIF-1α. Moreover, DMM inhibited excessive hyperpolarization of MMP after CPR, and prevented the release of cytochrome C. Therefore, inhibiting SDH by DMM alleviated brain damage after CA, and the main mechanisms included inhibiting the excessive hyperpolarization of MMP, reducing the generation of mtROS and stabilizing the structure of HIF-1α.

Establishing a Rodent Model of Ventricular Fibrillation Cardiac Arrest With Graded Histologic and Neurologic Damage With Different Cardiac Arrest Durations.

ABSTRACTPurpose:The aim of the study was to establish a ventricular fibrillation (VF) cardiac arrest (CA) resuscitation model with consistent neurologic and neuropathologic damage as potential therapeutic target.Methods:Prospectively randomized groups of experiments in two phases. In phase 1 four groups of male Sprague–Dawley rats (n = 5) were resuscitated after 6 min VFCA with 2 and 6 min basic life support durations (BLS) with and without adrenaline. In phase 2 the most promising group regarding return of spontaneous circulation (ROSC) and survival was compared with a group of 8 min CA. Resuscitability, neurologic deficit scores (NDS), and overall performance category (OPC) were assessed daily; histolopathology of the hippocampal CA1 region [hematoxylin and eosin- (viable neurons), Fluoro-Jade- (dying neurons), and Iba-1 immunostaining (microglial activation–semiquantitative)] on day 14.Results:Two minutes BLS and with adrenaline as most promising group of phase 1 compared with an 8 min group in phase 2 exhibited ROSC in 8 (80%) vs. 9 (82%) animals and survivors till day 14 in 7 (88%) (all OPC 1, NDS 0 ± 0) vs. 6 (67%) (5 OPC 1, 1 OPC 2, NDS 0.83 ± 2.4) animals. OPC and NDS were only significantly different at day 1 (OPC: P = 0.035; NDS: P = 0.003). Histopathologic results between groups were not significantly different; however, a smaller variance of extent of lesions was found in the 8 min group. Both CA durations caused graded neurologic, overall, such as histopathologic damage.Conclusions:This dynamic global ischemia model offers the possibility to evaluate further cognitive and novel neuroprotective therapy testing after CA.