Cardiac Arrest In Rats Research Articles

P073 Temporal pattern of brain injury and inflammation following cardiac arrest in rats

P073 Temporal pattern of brain injury and inflammation following cardiac arrest in rats

Vagus Nerve Stimulation Improves Mitochondrial Dysfunction in Post–cardiac Arrest Syndrome in the Asphyxial Cardiac Arrest Model in Rats

Cerebral mitochondrial dysfunction during post–cardiac arrest syndrome (PCAS) remains unclear, resulting in a lack of therapeutic options that protect against cerebral ischemia–reperfusion injury. We aimed to assess mitochondrial dysfunction in the hippocampus after cardiac arrest and whether vagus nerve stimulation (VNS) can improve mitochondrial dysfunction and neurological outcomes. In an asphyxial cardiac arrest model, male Sprague–Dawley rats were assigned to the vagus nerve isolation (CA) or VNS (CA + VNS) group. Cardiopulmonary resuscitation was performed 450 s after pulseless electrical activity. After the return of spontaneous circulation (ROSC), left cervical VNS was performed for 3 h in the CA + VNS group. Mitochondrial respiratory function was evaluated using high-resolution respirometry of the hippocampal tissue. The neurologic deficit score (NDS) and overall performance category (OPC) were assessed at 24, 48, and 72 h after resuscitation. The leak respiration and oxidative phosphorylation capacity of complex I (OXPHOS CI) at 6 h after ROSC were significantly higher in the CA + VNS group than in the CA group (p = 0.0308 and 0.0401, respectively). Compared with the trends of NDS and OPC in the CA group, the trends of those in the CA + VNS group were significantly different, thus suggesting a favorable neurological outcome in the CA + VNS group (p = 0.0087 and 0.0064 between times × groups interaction, respectively). VNS ameliorated mitochondrial dysfunction after ROSC and improved neurological outcomes in an asphyxial cardiac arrest rat model.

Targeting TNFα-mediated cytotoxicity using thalidomide after experimental cardiac arrest in rats: An exploratory study.

Cardiac arrest (CA) results in a central and systemic cytokine and inflammatory response. Thalidomide has been reported to be neuroprotective by selectively decreasing TNFα synthesis. We hypothesized that thalidomide would decrease the systemic and organ-specific TNFα/cytokine response and biomarkers of injury in rats subjected to 10 min CA. Naïves, CA treated with vehicle (CA) and CA treated with thalidomide (50 mg/kg; CA+T) were studied (n=6 per group). TNFα and key cytokines were assessed at 3 h after resuscitation in the cortex, hippocampus, striatum, cerebellum, plasma, heart and lung. Neuron specific enolase (NSE), S100b, cardiac troponin T (cTnT) and intestinal fatty acid binding protein (IFABP) were used to assess neuronal, glial, cardiac and intestinal damage, respectively. CA increased TNFα and multiple pro-inflammatory cytokines in plasma and selected tissues with no differences between the CA and CA+T groups in any region. NSE, S100b, cTnT and IFABP were increased after CA or CA+T vs. in the naïve group (all P<0.05) without significant differences between the CA and CA+T groups. In conclusion, CA resulted in a TNFα and cytokine response, with increased biomarkers of organ injury. Notably, thalidomide at a dose reported to improve the outcome in in vivo models of brain ischemia did not decrease TNFα or cytokine levels in plasma, brain or extracerebral organs, or biomarkers of injury. Although CA at 3 h post resuscitation produces a robust TNFα response, it cannot be ruled out that an alternative dosing regimen or assessment at other time-points might yield different results. The marked systemic and regional cytokine response to CA remains a potential therapeutic target.

Effects of Different Hypothermia on the Results of Cardiopulmonary Resuscitation in a Cardiac Arrest Rat Model.

Objective To investigate the optimal temperature of hypothermia treatment in rats with cardiac arrest caused by ventricular fibrillation (VF) after the return of spontaneous circulation (ROSC). Methods A total of forty-eight male Sprague-Dawley rats were induced by VF through the guidewire with a maximum of 5 mA current and untreated for 8 min. Cardiopulmonary resuscitation (CPR) was performed for 8 min followed by defibrillation (DF). Resuscitated rats were then randomized into the normothermia (37°C) group, milder (35°C) group, mild (33°C) group, or moderate (28°C) group. Hypothermia was immediately induced with surface cooling. The target temperature was maintained for 4 h before rewarming to 37 ± 0.5°C. Moreover, at the end of the 4 h, a rat in each group was randomly selected to be sacrificed for the cerebral cortex electron microscopy observation (n = 1). The other resuscitated animals were observed for up to 72 h after ROSC (n = 7). Left ventricular ejection fraction (LVEF) and left ventricular end diastolic volume (LVEDV) were measured. Survival time, survival rate, and neurological deficit score (NDS) were recorded for 72 h. Results During hypothermia, higher LVEF was observed in the hypothermia groups when compared with normothermia group (35°C vs. 37°C, p < 0.05, 33°C and 28°C vs. 37°C, p < 0.01). Among the hypothermia groups, LVEF was higher in the 28°C group than that of 35°C (p < 0.05). However, both the heart rate (HR) (p < 0.01) and LVEDV (28°C vs. 35°C, p < 0.01, 28°C vs. 37°C and 33°C, p < 0.05) were lowest in the 28°C group when compared with the other groups. There were no significant differences of LVEF and LVEDV between the group 35°C and 33°C (p > 0.05). After rewarming, the LVEF of 35°C group was higher than that of group 37°C, 33°C, and 28°C (35°C vs. 37°C and 28°C, p < 0.01, 35°C vs. 33°C, p < 0.05). Group 35°C and 33°C resulted in longer survival (p < 0.01), higher survival rate (p < 0.01), and lower NDS (35°C vs. 37°C and 28°C, p < 0.01, 33°C vs. 37°C and 28°C, p < 0.05) compared with the group 37°C and 28°C. The extent of damage to cerebral cortex cells in group of 35°C and 33°C was lighter than that in group of 37°C and 28°C. The 35°C group spent less time in the process of cooling and rewarming than the group 33°C and 28°C (p < 0.01). Conclusions An almost equal protective effect of milder hypothermia (35°C) and mild hypothermia (33°C) in cardiac arrest (CA) rats was achieved with more predominant effect than moderate hypothermia (28°C) and normothermia (37°C). More importantly, shorter time spent in cooling and rewarming was required in the 35°C group, indicating its potential clinical application. These findings support the possible use of milder hypothermia (35°C) as a therapeutic agent for postresuscitation.

Oxyhaemoglobin Level Measured Using Near-Infrared Spectrometer Is Associated with Brain Mitochondrial Dysfunction After Cardiac Arrest in Rats.

Cerebral blood oxygenation (CBO), measured using near-infrared spectroscopy (NIRS), can play an important role in post-cardiac arrest (CA) care as this emerging technology allows for noninvasive real-time monitoring of the dynamic changes of tissue oxygenation. We recently reported that oxyhaemoglobin (oxy-Hb), measured using NIRS, may be used to evaluate the quality of chest compressions by monitoring the brain tissue oxygenation, which is a critical component for successful resuscitation. Mitochondria are the key to understanding the pathophysiology of post-CA oxygen metabolism. In this study, we focused on mitochondrial dysfunction, aiming to explore its association with CBO parameters such as oxy-Hb and deoxyhaemoglobin (deoxy-Hb) or tissue oxygenation index (TOI). Male Sprague-Dawley rats were used in the study. We applied NIRS between the nasion and the upper cervical spine. Following 10 min of CA, the rats underwent cardiopulmonary resuscitation (CPR) with a bolus injection of 20μg/kg epinephrine. At 10 and 20 min after CPR, brain, and kidney tissues were collected. We isolated mitochondria from these tissues and evaluated the association between CBO and mitochondrial oxygen consumption ratios. There were no significant differences in the mitochondrial yields (10 vs. 20 min after resuscitation: brain, 1.33±0.68 vs. 1.30±0.75mg/g; kidney, 19.5±3.2 vs. 16.9±5.3mg/g, respectively). State 3 mitochondrial oxygen consumption rates, known as ADP-stimulated respiration, demonstrated a significant difference at 10 vs. 20 min after CPR (brain, 170±26 vs. 115±17nmol/min/mg protein; kidney, 170±20 vs. 130±16nmol/min/mg protein, respectively), whereas there was no significant difference in ADP non-dependent state 4 oxygen consumption rates (brain, 34.0±6.7 vs. 31.8±10nmol/min/mg protein; kidney, 29.8±4.8 vs. 21.0±2.6nmol/min/mg protein, respectively). Consequently, the respiratory control ratio (RCR=state 3/state 4) showed a significant difference over time, but this was only noted in the brain (brain, 5.0±0.29 vs. 3.8±0.64; kidney, 5.8±0.53 vs. 6.2±0.25nmol/min/mg protein, respectively). The oxy-Hb levels had a dynamic change after resuscitation, and they had a significant association with the RCR of the brain mitochondria (r=0.8311, p=0.0102), whereas deoxy-Hb and TOI did not (r=-0.1252, p=0.7677; r=0.4186, p=0.302, respectively). The RCRs of the kidney mitochondria did not have a significant association with CBO (oxy-Hb, r=-0.1087, p=0.7977; deoxy-Hb, r=0.1565, p=0.7113; TOI, r=-0.1687, p=0.6896, respectively). The brain mitochondrial respiratory dysfunction occurred over time, and it was seen at the time points between 10 and 20 min after CPR. The oxy-Hb level was associated with brain mitochondrial dysfunction during the early post-resuscitation period.

Histopathology and Tumor Necrosis Factor-α Expression in The Kidney of an Asphyxial Cardiac Arrest Rat Model

Histopathology and Tumor Necrosis Factor-α Expression in The Kidney of an Asphyxial Cardiac Arrest Rat Model

Effect of therapeutic hypothermia against renal injury in a rat model of asphyxial cardiac arrest: Α focus on the survival rate, pathophysiology and antioxidant enzymes.

Although multi-organ dysfunction is associated with the survival rate following cardiac arrest (CA), the majority of studies to date have focused on hearts and brains, and few studies have considered renal failure. The objective of the present study, therefore, was to examine the effects of therapeutic hypothermia on the survival rate, pathophysiology and antioxidant enzymes in rat kidneys following asphyxial CA. Rats were sacrificed one day following CA. The survival rate, which was estimated using Kaplan-Meier analysis, was 42.9% one day following CA. However, hypothermia, which was induced following CA, significantly increased the survival rate (71.4%). In normothermia rats with CA, the serum blood urea nitrogen level was significantly increased one day post-CA. In addition, the serum creatinine level was significantly increased one day post-CA. However, in CA rats exposed to hypothermia, the levels of urea nitrogen and creatinine significantly decreased following CA. Histochemical staining revealed a significant temporal increase in renal injury after the normothermia group was subjected to CA. However, renal injury was significantly decreased in the hypothermia group. Immunohistochemical analysis of the kidney revealed a significant decrease in antioxidant enzymes (copper-zinc superoxide dismutase, manganese superoxide dismutase, glutathione peroxidase and catalase) with time in the normothermia group. However, in the hypothermia group, these enzymes were significantly elevated following CA. Collectively, the results revealed that renal dysfunction following asphyxial CA was strongly associated with the early survival rate and therapeutic hypothermia reduced renal injury via effective antioxidant mechanisms.

Hydrogen gas with extracorporeal cardiopulmonary resuscitation improves survival after prolonged cardiac arrest in rats

BackgroundDespite the benefits of extracorporeal cardiopulmonary resuscitation (ECPR) in cohorts of selected patients with cardiac arrest (CA), extracorporeal membrane oxygenation (ECMO) includes an artificial oxygenation membrane and circuits that contact the circulating blood and induce excessive oxidative stress and inflammatory responses, resulting in coagulopathy and endothelial cell damage. There is currently no pharmacological treatment that has been proven to improve outcomes after CA/ECPR. We aimed to test the hypothesis that administration of hydrogen gas (H2) combined with ECPR could improve outcomes after CA/ECPR in rats.MethodsRats were subjected to 20 min of asphyxial CA and were resuscitated by ECPR. Mechanical ventilation (MV) was initiated at the beginning of ECPR. Animals were randomly assigned to the placebo or H2 gas treatment groups. The supplement gas was administered with O2 through the ECMO membrane and MV. Survival time, electroencephalography (EEG), brain functional status, and brain tissue oxygenation were measured. Changes in the plasma levels of syndecan-1 (a marker of endothelial damage), multiple cytokines, chemokines, and metabolites were also evaluated.ResultsThe survival rate at 4 h was 77.8% (7 out of 9) in the H2 group and 22.2% (2 out of 9) in the placebo group. The Kaplan–Meier analysis showed that H2 significantly improved the 4 h-survival endpoint (log-rank P = 0.025 vs. placebo). All animals treated with H2 regained EEG activity, whereas no recovery was observed in animals treated with placebo. H2 therapy markedly improved intra-resuscitation brain tissue oxygenation and prevented an increase in central venous pressure after ECPR. H2 attenuated an increase in syndecan-1 levels and enhanced an increase in interleukin-10, vascular endothelial growth factor, and leptin levels after ECPR. Metabolomics analysis identified significant changes at 2 h after CA/ECPR between the two groups, particularly in d-glutamine and d-glutamate metabolism.ConclusionsH2 therapy improved mortality in highly lethal CA rats rescued by ECPR and helped recover brain electrical activity. The underlying mechanism might be linked to protective effects against endothelial damage. Further studies are warranted to elucidate the mechanisms responsible for the beneficial effects of H2 on ischemia–reperfusion injury in critically ill patients who require ECMO support.

Abstract 9180: Importance of Preventing Decreased Levels of Lysophosphatidylcholine—DHA in Brain and Plasma for Attenuating Brain Injury After Cardiac Arrest

Introduction: Lysophosphatidylcholine (LPC) was found to be decreased in plasma in the early phase of resuscitation after cardiac arrest (CA), including a species containing docosahexaenoic acid (LPC-DHA). Supplementing this deficiency of plasma LPC-DHA post-CA significantly attenuated brain dysfunction implicating a causative role of plasma decreased LPC-DHA for brain injury. Previous studies showed the importance of LPC-DHA as a carrier of DHA to maintain proper brain function. However, the role of LPC-DHA for brain function has not been fully understood. Objective: This study is aimed at determining the importance of maintaining proper brain LPC-DHA level via plasma supplementation to prevent brain damage after CA using human patients, animal model, and in-vitro cell studies. Methods and Results: We first evaluated associations between the plasma LPC-DHA levels and neurological outcomes using 45 post-CA patients. We then measured LPC-DHA levels and histological, biochemical, metabolic alterations in the plasma and brain after 10 min CA rat model and examined how these alterations were attenuated by supplementing LPC-DHA. Finally, we further investigated the beneficial effect of LPC-DHA using cell cultures. We found that the decreased plasma LPC-DHA was strongly associated with neurological outcomes and disappearance of difference between gray and white matter in the brain after CA in human patients. In rats, the decreased plasma LPC-DHA was associated with decreased level of brain LPC-DHA after CA, and supplementing plasma LPC-DHA normalized the brain levels of LPC-DHA and alleviated neuronal cell death, activation of astrocyte, and expression of various inflammatory and mitochondrial dysfunction genes. We also found normalized overall metabolic alterations from the untargeted metabolomics analysis. Furthermore, LPC treatment showed a similar protective effect for neurons and astrocytes in mixed primary brain cell cultures. Conclusion: The attenuation of biochemical and physiologic alterations, and the normalization of decreased brain LPC-DHA post-CA with LPC-DHA supplementation demonstrate plasma LPC-DHA is important for the maintenance of proper brain LPC-DHA levels, which is essential for preventing brain damage post-CA.

Sodium-Glucose Co-Transporter 2 Inhibition With Empagliflozin Improves Cardiac Function After Cardiac Arrest in Rats by Enhancing Mitochondrial Energy Metabolism.

Empagliflozin is a newly developed antidiabetic drug to reduce hyperglycaemia by highly selective inhibition of sodium–glucose co-transporter 2. Hyperglycaemia is commonly seen in patients after cardiac arrest (CA) and is associated with worse outcomes. In this study, we examined the effects of empagliflozin on cardiac function in rats with myocardial dysfunction after CA. Non-diabetic male Sprague–Dawley rats underwent ventricular fibrillation to induce CA, or sham surgery. Rats received 10 mg/kg of empagliflozin or vehicle at 10 min after return of spontaneous circulation by intraperitoneal injection. Cardiac function was assessed by echocardiography, histological analysis, molecular markers of myocardial injury, oxidative stress, mitochondrial ultrastructural integrity and metabolism. We found that empagliflozin did not influence heart rate and blood pressure, but left ventricular function and survival time were significantly higher in the empagliflozin treated group compared to the group treated with vehicle. Empagliflozin also reduced myocardial fibrosis, serum cardiac troponin I levels and myocardial oxidative stress after CA. Moreover, empagliflozin maintained the structural integrity of myocardial mitochondria and increased mitochondrial activity after CA. In addition, empagliflozin increased circulating and myocardial ketone levels as well as heart β-hydroxy butyrate dehydrogenase 1 protein expression. Together, these metabolic changes were associated with an increase in cardiac energy metabolism. Therefore, empagliflozin favorably affected cardiac function in non-diabetic rats with acute myocardial dysfunction after CA, associated with reducing glucose levels and increasing ketone body oxidized metabolism. Our data suggest that empagliflozin might benefit patients with myocardial dysfunction after CA.

The effect of Glibenclamide on somatosensory evoked potentials after cardiac arrest in rats.

Science continues to search for a neuroprotective drug therapy to improve outcomes after cardiac arrest (CA). The use of glibenclamide (GBC) has shown promise in preclinical studies, but its effects on neuroprognostication tools are not well understood. We aimed to investigate the effect of GBC on somatosensory evoked potential (SSEP) waveform recovery post CA and how this relates to the early prediction of functional outcome, with close attention to arousal and somatosensory recovery, in a rodent model of CA. Sixteen male Wistar rats were subjected to 8-min asphyxia CA and assigned to GBC treatment (n = 8) or control (n = 8) groups. GBC was administered as a loading dose of 10μg/kg intraperitoneally 10min after the return of spontaneous circulation, followed by a maintenance dosage of 1.6μg/kg every 8h for 24h. SSEPs were recorded from baseline until 150min following CA. Coma recovery, arousal, and brainstem function, measured by subsets of theneurological deficit score (NDS), werecompared between both groups. SSEP N10 amplitudes were compared between the two groups at 30, 60, 90, and 120min post CA. Rats treated with GBC had higher sub-NDS scores post CA, with improved arousal and brainstem function recovery (P = 0.007). Both groups showed a gradual improvement of SSEP N10 amplitude over time, from 30 to 120min post CA. Rats treated with GBC showed significantly better SSEP recovery at every time point (P < 0.001 for 30, 60, and 90min; P = 0.003 for 120min). In the GBC group, the N10 amplitude recovered to baseline by 120min post CA. Quantified Cresyl violet staining revealed a significantly greater percentage of damage in the control group compared with the GBC treatment group (P=0.004). Glibenclamide improves coma recovery, arousal, and brainstem function after CA with decreased number of ischemic neurons in a rat model. GBC improves SSEP recovery post CA, with N10 amplitude reaching the baseline value by 120min, suggesting early electrophysiologic recovery with this treatment. This medication warrants further exploration as a potential drug therapy to improve functional outcomes in patients after CA.

Neuroprotective mechanism of autophagy in bradykinin postconditioning after cardiac arrest in rats

To explore the protective effects of bradykinin postconditioning on cardiopulmonary resuscitation (CPR) rats, and to assess the underlying mechanisms. Forty-eight adult male Sprague-Dawley (SD) rats were randomly divided into four groups according to random number table: Sham operation group, cardiac arrest (CA) group, bradykinin treatment (BK) group, and AMP-activated protein kinase (AMPK) inhibitor Compound C+ bradykinin treatment (CP+BK) group, finally, 8 rats in each group were taken for follow-up experiment. CA was induced by asphyxia. Rats in the Sham group received arteriovenous catheterization, endotracheal intubation, and mechanical ventilation, without CA. Compound C (250 μg/kg) was intraperitoneally injected in CP+BK group 30 minutes before CA, and the same volume of dimethyl sulfoxide (DMSO) was given in the remaining groups. Bradykinin (150 μg/kg) was intraperitoneally injected in BK group and CP+BK group 48 hours after restoration of spontaneous circulation (ROSC), and same volume of saline was given in the remaining groups. The neural function of rats in each group was evaluated with neurological deficit score (NDS) 72 hours after ROSC. Microtubule-associated protein light chain 3 (LC3) and p62 expressions were detected by immunohistochemistry, autophagosomes were observed by transmission electron microscopy, and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling method (TUNEL) assay was used to assess apoptosis. Compared with the Sham group, the NDS was decreased (60.75±5.80 vs. 80.00±0.00, P < 0.01), the expression levels of LC3 and p62 elevated [LC3 (A value): 1.04±0.64 vs. 0.40±0.14, p62 (A value): 2.75±0.57 vs. 0.36±0.12, both P < 0.05], the number of autophagosomes and apoptotic cells increased in the CA group [(39.00±8.00)% vs. (3.87±1.90)%, P < 0.05]. Compared with the CA group, the NDS (67.75±6.32 vs. 60.75±5.80, P < 0.05), the expression of LC3 (A value: 1.60±0.34 vs. 1.04±0.64, P < 0.05), and the number of autophagosomes increased in the BK group, while the expression of p62 and the rate of apoptotic cells reduced [p62 (A value): 1.51±0.32 vs. 2.75±0.57, apoptotic cells rate: (23.03±1.91)% vs. (39.00±8.00)%, both P < 0.05]. Compared with the BK group, the NDS (59.00±8.19 vs. 67.75±6.32, P < 0.05), the expression of LC3 (A value: 0.62±0.41 vs. 1.60±0.34, P < 0.05) and the number of autophagosomes declined in the CP+BK group, while the expression of p62 and the rate of apoptotic cells elevated [p62 (A value): 3.50±0.47 vs. 1.51±0.32, apoptotic cells rate: (44.53±10.15)% vs. (23.03±1.91)%, both P < 0.05]. Bradykinin postconditioning played a neuroprotective role in CPR rats by activating autophagy and reducing apoptosis.

High-resolution respirometry for evaluation of mitochondrial function on brain and heart homogenates in a rat model of cardiac arrest and cardiopulmonary resuscitation

The physiology and physiopathology process of mitochondrial function following cardiac arrest remains poorly understood. We aimed to assess mitochondrial respiratory function on the heart and brain homogenates from cardiac arrest rats. The expression level of SIRT1/PGC-1α pathway was measured by immunoblotting. 30 rats were assigned to the CA group and the sham group. Rats of CA were subjected to 6 min of untreated ventricular fibrillation (VF) followed by 8 min of cardiopulmonary resuscitation (CPR). Mitochondrial respiratory function was compromised following CA and I/R injury, as indicated by CIL (451.46 ± 71.48 vs. 909.91 ± 5.51 pmol/min*mg for the heart and 464.14 ± 8.22 vs. 570.53 ± 56.33 pmol/min*mg for the brain), CI (564.04 ± 64.34 vs. 2729.52 ± 347.39 pmol/min*mg for the heart and 726.07 ± 85.78 vs. 1762.82 ± 262.04 pmol/min*mg for the brain), RCR (1.88 ± 0.46 vs. 3.57 ± 0.38 for the heart and 2.05 ± 0.19 vs. 3.49 ± 0.19, for the brain) and OXPHOS coupling efficiency (0.45 ± 0.11 vs. 0.72 ± 0.03 for the heart and 0.52 ± 0.05 vs. 0.71 ± 0.01 for the brain). However, routine respiration was lower in the heart and comparable in the brain after CA. CIV did not change in the heart but was enhanced in the brain. Furthermore, both SIRT1 and PGC-1α were downregulated concurrently in the heart and brain. The mitochondrial respiratory function was compromised following CA and I/R injury, and the major affected respiratory state is complex I-linked respiration. Furthermore, the heart and the brain respond differently to the global I/R injury after CA in mitochondrial respiratory function. Inhibition of the SIRT1/PGC-1α pathway may be a major contributor to the impaired mitochondrial respiratory function.

Increased cerebral endothelium-dependent vasodilation in rats in the postcardiac arrest period.

Cardiovascular lability is common after cardiac arrest. We investigated whether altered endothelial function is present in cerebral and mesenteric arteries 2 and 4 h after resuscitation. Male Sprague-Dawley rats were anesthetized, intubated, ventilated, and intravascularly catheterized whereupon rats were randomized into four groups. Following 7 min of asphyxial cardiac arrest and subsequent resuscitation, cardiac arrest and sham rats were observed for either 2 or 4 h. Neuron-specific enolase levels were measured in blood samples. Middle cerebral artery segments and small mesenteric arteries were isolated and examined in microvascular myographs. qPCR and immunofluorescence analysis were performed on cerebral arteries. In cerebral arteries, bradykinin-induced vasodilation was inhibited in the presence of either calcium-activated K+ channel blockers (UCL1684 and senicapoc) or the nitric oxide (NO) synthase inhibitor, Nω-nitro-L-arginine methyl ester hydrochloride (l-NAME), whereas the combination abolished bradykinin-induced vasodilation across groups. Neuron-specific enolase levels were significantly increased in cardiac arrest rats. Cerebral vasodilation was comparable between the 2-h groups, but markedly enhanced in response to bradykinin, NS309 (an opener of small and intermediate calcium-activated K+ channels), and sodium nitroprusside 4 h after cardiac arrest. Endothelial NO synthase and guanylyl cyclase subunit α-1 mRNA expression was unaltered after 2 h, but significantly decreased 4 h after resuscitation. In mesenteric arteries, the endothelium-dependent vasodilation was comparable between corresponding groups at both 2 and 4 h. Our findings show enhanced cerebral endothelium-dependent vasodilation 4 h after cardiac arrest mediated by potentiated endothelial-derived hyperpolarization and NO pathways. Altered cerebral endothelium-dependent vasodilation may contribute to disturbed cerebral perfusion after cardiac arrest.NEW & NOTEWORTHY This is the first study, to our knowledge, to demonstrate enhanced endothelium-dependent vasodilation in middle cerebral arteries in a cardiac arrest rat model. The increased endothelium-dependent vasodilation was a result of potentiated endothelium-derived hyperpolarization and endothelial nitric oxide pathways. Immunofluorescence microscopy confirmed the presence of relevant receptors and eNOS in cerebral arteries, whereas qPCR showed altered expression of genes related to guanylyl cyclase and eNOS. Altered endothelium-dependent vasoregulation may contribute to disturbed cerebral blood flow in the postcardiac arrest period.

Hypothermic treatment reduces matrix metalloproteinase-9 expression and damage in the liver following asphyxial cardiac arrest in rats

BackgroundHypothermic treatment is known to protect organs against cardiac arrest (CA) and improves survival rate. However, few studies have evaluated the effects of hypothermia on CA-induced liver damages. This study was designed to analyzed the possible protective effects of hypothermia on the liver after asphyxial CA (ACA). Rats were randomly subjected to 5 min of ACA followed by return of spontaneous circulation (ROSC). Body temperature was controlled at 37 ± 0.5 °C (normothermia group) or 33 ± 0.5 °C (hypothermia group) for 4 h after ROSC. Liver tissues were extracted and examined at 6 h, 12 h, 1 day, and 2 days after ROSC.ResultsThe expression of infiltrated neutrophil marker CD11b and matrix metallopeptidase-9 (MMP9) was investigated via immunohistochemistry. Morphological damage was assessed via hematoxylin and eosin (H & E) staining. Hypothermic treatment improved the survival rate at 6 h, 12 h, 1 day, and 2 days after ACA. Based on immunohistochemical analysis, the expression of CD11b and MMP9 was significantly increased from 6 h after ACA in the normothermia group. However, the expressions of CD11b and MMP9 was significantly decreased in the hypothermia group compared with that of the normothermia group. In addition, in the results of H & E, sinusoidal dilatation and vacuolization were apparent after ACA; however, these ACA-induced structural changes were reduced by the 4 h-long hypothermia.ConclusionsIn conclusion, hypothermic treatment for 4 h inhibited the increases in CD11b and MMP9 expression and reduced the morphological damages in the liver following ACA in rats. This study suggests that hypothermic treatment after ACA reduces liver damages by regulating the expression of CD11b and MMP9.

Phospholipid Screening Postcardiac Arrest Detects Decreased Plasma Lysophosphatidylcholine: Supplementation as a New Therapeutic Approach.

Cardiac arrest and subsequent resuscitation have been shown to deplete plasma phospholipids. This depletion of phospholipids in circulating plasma may contribute to organ damage postresuscitation. Our aim was to identify the diminishment of essential phospholipids in postresuscitation plasma and develop a novel therapeutic approach of supplementing these depleted phospholipids that are required to prevent organ dysfunction postcardiac arrest, which may lead to improved survival. Clinical case control study followed by translational laboratory study. Research institution. Adult cardiac arrest patients and male Sprague-Dawley rats. Resuscitated rats after 10-minute asphyxial cardiac arrest were randomized to be treated with lysophosphatidylcholine specie or vehicle. We first performed a phospholipid survey on human cardiac arrest and control plasma. Using mass spectrometry analysis followed by multivariable regression analyses, we found that plasma lysophosphatidylcholine levels were an independent discriminator of cardiac arrest. We also found that decreased plasma lysophosphatidylcholine was associated with poor patient outcomes. A similar association was observed in our rat model, with significantly greater depletion of plasma lysophosphatidylcholine with increased cardiac arrest time, suggesting an association of lysophosphatidylcholine levels with injury severity. Using a 10-minute cardiac arrest rat model, we tested supplementation of depleted lysophosphatidylcholine species, lysophosphatidylcholine(18:1), and lysophosphatidylcholine(22:6), which resulted in significantly increased survival compared with control. Furthermore, the survived rats treated with these lysophosphatidylcholine species exhibited significantly improved brain function. However, supplementing lysophosphatidylcholine(18:0), which did not decrease in the plasma after 10-minute cardiac arrest, had no beneficial effect. Our data suggest that decreased plasma lysophosphatidylcholine is a major contributor to mortality and brain damage postcardiac arrest, and its supplementation may be a novel therapeutic approach.

Polyphenol-assisted facile assembly of bioactive nanoparticles for targeted therapy of heart diseases

It remains a great challenge for targeted therapy of heart diseases. To achieve desirable heart targeting, we developed a polyphenol-assisted nanoprecipitation/self-assembly approach for facile engineering of functional nanoparticles. Three different materials were employed as representative carriers, while gallic acid, catechin, epigallocatechin gallate, and tannic acid (TA) served as typical polyphenols with varied numbers of phenolic hydroxyl groups. By optimizing different parameters, such as polyphenol types and the weight ratio of carrier materials and polyphenols, well-defined nanoparticles with excellent physicochemical properties can be easily prepared. Regardless of various carrier materials, TA-derived nanoparticles showed potent reactive oxygen species-scavenging activity, especially nanoparticles produced from a cyclodextrin-derived bioactive material (TPCD). By internalization into cardiomyocytes, TPCD/TA nanoparticles (defined as TPTN) effectively protected cells from hypoxic-ischemic injury. After intravenous injection, TPTN considerably accumulated in the injured heart in two murine models of ventricular fibrillation cardiac arrest in rats and myocardial hypertrophy in mice. Correspondingly, intravenously delivered TPTN afforded excellent therapeutic effects in both heart diseases. Preliminary experiments also revealed good safety of TPTN. These results substantiated that TPTN is a promising nanotherapy for targeted treatment of heart diseases, while polyphenol-assisted self-assembly is a facile but robust strategy to develop heart-targeting delivery systems.

English

Cardiac arrest (CA) is a sudden interruption in the effective blood flow due to heart failure. The current research aimed to conduct the pathophysiological and histopathological analysis in the kidney in asphyxial cardiac arrest rat model. Cardiac arrest was induced by intravenous injection of vecuronium bromide (2 mg/kg), following stop of mechanical ventilation. Rats were kept on the CA condition for 5 minutes. After that, cardiopulmonary resuscitation (CPR) was done to achieve return of spontaneous circulation (ROSC) following intravenous injection of epinephrine bolus (0.005 mg/kg), sodium bicarbonate (1 mEq/kg) and turn on mechanical ventilation. Then Rats were sacrificed after cardiopulmonary resuscitation (CPR) following asphyxial CA at 6 hrs, 12 hrs, 1 day, 2 days, and 5 days. The intensity of renal injury measured by the serum levels of blood urea nitrogen (BUN), creatinine (Crtn). Moreover, Hematoxylin &amp; eosin, and Periodic Acid Schiff staining in the kidney was done for evaluating the renal histopathological changes. Furthermore, COX-2 immunoreactivity and western analysis were performed in the kidney. Survival rate declined following ROSC compared to the sham group, it showed 80% at 6 hrs and decreased time-dependently to 8% at 5 days. In this study, serum BUN and Crtn levels and renal histopathological scores significantly increased after ROSC in CA. Moreover, COX-2 expression also increased after ROSC in comparison to the sham group with its peak level at 5 days following CA. Renal histological damage score and COX-2 expression were upregulated after ROSC following CA. These results direct that COX-2 takes part in the asphyxial CA-induced ischemic renal injury

The effect of high-dose intramuscular epinephrine on the recovery of spontaneous circulation in an asphyxia\u2010induced cardiac arrest rat model

BackgroundObtaining vascular access can be challenging during resuscitation following cardiac arrest, and it is particularly difficult and time-consuming in paediatric patients. We aimed to compare the efficacy of high-dose intramuscular (IM) versus intravascular (IV) epinephrine administration with regard to the return of spontaneous circulation (ROSC) in an asphyxia-induced cardiac arrest rat model.Methods Forty-five male Sprague-Dawley rats were used for these experiments. Cardiac arrest was induced by asphyxia, and defined as a decline in mean arterial pressure (MAP) to 20 mmHg. After asphyxia-induced cardiac arrest, the rats were randomly allocated into one of 3 groups (control saline group, IV epinephrine group, and IM epinephrine group). After 540 s of cardiac arrest, cardiopulmonary resuscitation was performed, and IV saline (0.01 cc/kg), IV (0.01 mg/kg, 1:100,000) epinephrine or IM (0.05 mg/kg, 1:100,000) epinephrine was administered. ROSC was defined as the achievement of an MAP above 40 mmHg for more than 1 minute. Rates of ROSC, haemodynamics, and arterial blood gas analysis were serially observed.ResultsThe ROSC rate (61.5%) of the IM epinephrine group was less than that in the IV epinephrine group (100%) but was higher than that of the control saline group (15.4%) (log-rank test). There were no differences in MAP between the two groups, but HR in the IM epinephrine group (beta coefficient = 1.02) decreased to a lesser extent than that in the IV epinephrine group with time.ConclusionsIM epinephrine induced better ROSC rates compared to the control saline group in asphyxia-induced cardiac arrest, but not compared to IV epinephrine. The IM route of epinephrine administration may be a promising option in an asphyxia-induced cardiac arrest.

Combined transplantation of neural stem cells and bone marrow mesenchymal stem cells promotes neuronal cell survival to alleviate brain damage after cardiac arrest via microRNA-133b incorporated in extracellular vesicles.

Neural stem cell (NSC) transplantation has prevailed as a promising protective strategy for cardiac arrest (CA)-induced brain damage. Surprisingly, the poor survival of neuronal cells in severe hypoxic condition restricts the utilization of this cell-based therapy. Extracellular vesicles (EVs) transfer microRNAs (miRNAs) between cells are validated as the mode for the release of several therapeutic molecules. The current study reports that the bone marrow mesenchymal stem cells (BMSCs) interact with NSCs via EVs thereby affecting the survival of neuronal cells. Hypoxic injury models of neuronal cells were established using cobalt chloride, followed by co-culture with BMSCs and NSCs alone or in combination. BMSCs combined with NSCs elicited as a superior protocol to stimulate neuronal cell survival. BMSCs-derived EVs could protect neuronal cells against hypoxic injury. Silencing of miR-133b incorporated in BMSCs-derived EVs could decrease the cell viability and the number of NeuN-positive cells and increase the apoptosis in the CA rat model. BMSCs-derived EVs could transfer miR-133b to neuronal cells to activate the AKT-GSK-3β-WNT-3 signaling pathway by targeting JAK1. Our study demonstrates that NSCs promotes the release of miR-133b from BMSCs-derived EVs to promote neuronal cell survival, representing a potential therapeutic strategy for the treatment of CA-induced brain damage.