Rat Model Of Cardiopulmonary Resuscitation Research Articles

The role of (18F)-fluoro-D-glucose positron emission tomography/computed tomography in the surveillance of abnormal myocardial energy metabolism and cardiac dysfunction in a rat model of cardiopulmonary resuscitation.

To investigate the feasibility and usefulness of 2-deoxy-2-(18F)-fluoro-D-glucose positron emission tomography/computed tomography [(18F)-FDG PET/CT] as a novel examination in the surveillance of abnormal myocardial energy metabolism and cardiac dysfunction after cardiopulmonary resuscitation (CPR). Thirteen male Sprague-Dawley rats were randomly divided into a sham group (n = 4), CPR group (n = 4), and trimetazidine (TMZ) + CPR group (n = 5). The expression levels of the myocardial injury marker cardiac troponin I (CTNI) in serum were tested at 6 hours after CPR or TMZ + CPR. The ejection fraction and fraction shortening were evaluated by echocardiography. (18F)-FDG PET/CT was used to measure the FDG uptake and the standardized uptake value (SUV) after CPR or TMZ + CPR for 6 hours. The intermediary carbohydrate metabolites of glycolysis including phosphoenolpyruvate, 3-phospho-D-glycerate, and the lactate/pyruvate ratio were detected through the multiple reaction monitoring approach. Simultaneously, the authors also tested the expression levels of the total adenosine triphosphate (ATP) and the key intermediate products of glucose ovidation as alpha ketoglutarate, citrate, and succinate in the myocardium. The authors found that the aerobic oxidation of glucose was reduced, and the anaerobic glycolysis was significantly enhanced in the myocardium in the early stage of CPR. Meanwhile, the myocardial injury marker CTNI was upregulated considerably (P = 0.014, P = 0.021), and the left ventricular function of the animal heart also markedly deteriorated with the downregulation of ATP after CPR. In contrast, myocardial injury and cardiac function were greatly improved with the increase of ATP in the CPR + TMZ group. In addition, aerobic glucose oxidation metabolites were significantly increased (P < 0.05) and anaerobic glycolysis metabolites were significantly decreased (P < 0.05) after CPR in the myocardium. Surprisingly, (18F)-FDG PET/CT could track the above changes by detecting the FDG uptake value and the SUV. Glucose metabolism is an essential factor for myocardial self-repair after CPR. (18F) FDG PET/CT, as a non-invasive technology, can monitor myocardial energy metabolism and cardiac function by tracking changes in glucose metabolism after CPR.

IVABRADINE-INDUCED HEART RATE REDUCTION INCREASES THE SEVERITY OF POSTRESUSCITATION MYOCARDIAL DYSFUNCTION IN A RAT MODEL OF CARDIOPULMONARY RESUSCITATION.

Aims: A rapid heart rate (HR) that occurs after cardiopulmonary resuscitation (CPR) is a short-term compensatory mechanism preserving cardiac output. However, if of long duration, it is unfavorable for myocardial function postresuscitation because of disrupted balance between myocardial oxygen supply and demand. This raises the assumption that such a sustained fast HR should be regulated. The present study aimed to investigate the follow-on effect of ivabradine (a specific inhibitor of the I f current of the sinoatrial node)-induced HR reduction (HRR) on postresuscitation myocardial function in a rat model of CPR. Methods and results: Six minutes of ventricular fibrillation and 8 min of CPR were performed on Sprague-Dawley rats. All 32 resuscitated animals were then randomized into saline and ivabradine groups, each group having nonsurvival and survival subgroups (n = 8 each). Saline or ivabradine (0.5 mL/kg) was administered at 1 h postresuscitation. Heart rate, myocardial function as expressed by cardiac output, ejection fraction, and myocardial performance index were assessed at baseline and hourly from 1 to 5 h postresuscitation. Heart rate variability was analyzed at baseline and at 1, 3, and 5 h postresuscitation. Serum epinephrine and cardiac troponin I at baseline and at 1, 3, and 5 h postresuscitation in nonsurvival subgroup were measured. Survival duration in the survival subgroup was observed. The baseline HR was approximately 390 beats/min (bpm). After resuscitation, an average increase of Δ ≈ +15 bpm (relative ratio ≈ +3.8%) with a resultant HR of 405 bpm lasting more than 5 h occurred. Ivabradine group achieved a steady HRR of Δ ≈ -30 bpm (relative ratio ≈ -7.4%) as compared with saline group ( P < 0.01). Postresuscitation myocardial function was significantly worse in the ivabradine group (all P < 0.01). Heart rate variability was significantly impaired in the ivabradine group (all P < 0.05). Serum cardiac troponin I and epinephrine concentration were significantly higher in the ivabradine group (all P < ?0.01). Survival duration was significantly shortened in the ivabradine group as compared with the saline group (388 vs. 526 min, P < ?0.01). Conclusions: Ivabradine-induced HRR increases the severity of postresuscitation myocardial dysfunction and shortens survival duration in a rat model of CPR.

The Selective NLRP3-inflammasome inhibitor MCC950 Mitigates Post-resuscitation Myocardial Dysfunction and Improves Survival in a Rat Model of Cardiac Arrest and Resuscitation

PurposeTo investigate the effects of the selective NLRP3 inflammasome inhibitor MCC950 on post-resuscitation myocardial function and survival in a rat model of cardiopulmonary resuscitation (CPR).MethodsThirty-six Sprague Dawley rats were randomized into three groups: (1) MCC950, (2) control, and (3) sham. Each group consisted of a 6 h non-survival subgroup (n = 6) and a 48 h survival subgroup (n = 6). Ventricular fibrillation (VF) was induced and untreated for 6 min. CPR was initiated and continued for 8 min. Resuscitation was attempted with a 4 J defibrillation. MCC950 (10 mg/kg) or vehicle was administered via intraperitoneal injection immediately after the return of spontaneous circulation (ROSC). Myocardial function and sublingual microcirculation were measured after ROSC in the non-survival subgroups. Plasma levels of interleukin Iβ (IL-1β) and cardiac troponin I (cTnI) were measured at baseline and 6 h in the non-survival subgroups. Heart tissue was harvested to measure the NLRP3 inflammasome constituents, including NLRP3, apoptosis-associated speck-like protein (ASC), Caspase-1, and IL-1β. Survival duration and neurologic deficit score (NDS) were recorded and evaluated among survival groups.ResultsPost-resuscitation myocardial function and sublingual microcirculation were improved in MCC950 compared with control (p < 0.05). IL-1β and cTnI were decreased in MCC950 compared to control (p < 0.01). The MCC950 treated groups showed significantly reduced ASC, caspase-1, and IL-1β compared with the control group (p < 0.05). Survival at 48 h after ROSC was greater in MCC950 (p < 0.05) with improved NDS (p < 0.05).ConclusionAdministration of MCC950 following ROSC mitigates post-resuscitation myocardial dysfunction and improves survival.

Effects of NLRP3 inflammasome blockade on postresuscitation cerebral function in a rat model of cardiopulmonary resuscitation

Cardiac arrest (CA) remains a major public health issue. Inflammatory responses with overproduction of interleukin-1β regulated by NLRP3 inflammasome activation play a crucial role in cerebral ischemia/reperfusion injury. We investigated the effects of the selective NLRP3-inflammasome inhibitor MCC950 on post-resuscitation cerebral function and neurologic outcome in a rat model of cardiac arrest. Thirty-six male rats were randomized into the MCC950 group, the control group, or the sham group (N = 12 of each group). Each group was divided into a 6 h non-survival subgroup (N = 6) and a 24 h survival subgroup (N = 6). Ventricular fibrillation (VF) was electrically induced and untreated for 6 min, followed by 8 min of precordial compressions and mechanical ventilation. Resuscitation was attempted with a 4J defibrillation. Either MCC950 (10 mg/kg) or vehicle was injected intraperitoneally immediately after the return of spontaneous circulation (ROSC). Rats in the sham group underwent the same surgical procedures without VF and CPR. Brain edema, cerebral microcirculation, plasma interleukin Iβ (IL-1β), and neuron-specific enolase (NSE) concentration were measured at 6 h post-ROSC of non-survival subgroups, while 24 h survival rate, neurological deficits were measured at 24 h post-ROSC of survival subgroups. Post-resuscitation brain edema was significantly reduced in animals treated with MCC950 (p < 0.05). Cerebral perfused vessel density (PVD) and microcirculatory flow index (MFI) values were significantly higher in the MCC950 group compared with the control group (p < 0.05). The plasma concentrations of IL-1β and NSE were significantly decreased in animals treated with MCC950 compared with the control group (p < 0.05). 24 h-survival rate and neurological deficits score (NDS) was also significantly improved in the MCC950 group compared with the control group (p < 0.05). NLRP3 inflammasome blockade with MCC950 at ROSC reduces the circulatory level of IL-1β, preserves cerebral microcirculation, mitigates cerebral edema, improves the 24 h-survival rate, and neurological deficits.

Abstract 21: Effects of the Selective NLRP3-Inflammasome Inhibitor MCC950 on Post-Resuscitation Myocardial and Cerebral Function in a Rat Model of Cardiopulmonary Resuscitation

Introduction: NLRP3 inflammasome mediated pyroptosis has been demonstrated to increase myocardial and cerebral ischemia/reperfusion injury. MCC950 is a newly developed highly selective inhibitor of the NLRP3 inflammasome. Hypothesis: MCC950 administered following resuscitation will reduce the severity of post-resuscitation myocardial and cerebral dysfunction and improve duration of survival in a rat model of CPR. Methods: 15 male Sprague-Dawley rats weighting between 450-550 g were randomized into three groups: 1) MCC950 2) Control 3) Sham. Ventricular fibrillation (VF) was induced and untreated for 6 min. CPR was then initiated and continued for 8 min. Resuscitation was attempted with a 4 J defibrillation. Either MCC950 (10mg/kg) or vehicle was administered intraperitoneal (IP) in line with cardiac injury animal studies immediately after return of spontaneous circulation (ROSC). Sham underwent the same surgical procedure without VF and CPR. Sublingual microcirculation was measured at baseline (BL), 3, 6 and 48 hrs after ROSC. Ejection fraction (EF) was measured at BL, 1, 3, 6 and 48 hrs after ROSC. Neurologic Deficit Score (NDS) was recorded at 48 hrs after resuscitation. Results: Post-resuscitation ejection fraction and perfused sublingual vessel density were greater in MCC950 compared to control (p&lt;0.05). NDS was also improved in MCC950 compared to control (110 vs 425, p&lt;0.05). Survival at 48 hrs after ROSC was greater in MCC950 (4/5 vs 1/5, p&lt;0.05). Conclusion: Administration of MCC950 following ROSC mitigates post-resuscitation myocardial and cerebral dysfunction, improves sublingual microcirculation and duration of survival in a rat model of CPR.

Abstract 20: Peripheral Intravenous Analysis Detects Return of Spontaneous Circulation Without Interruption of Chest Compressions in a Rat Model of Cardiopulmonary Resuscitation

Introduction: A higher chest compression fraction (CCF) or percentage of time providing chest compressions is associated with improved survival after cardiac arrest (CA). Pauses in chest compression duration during cardiopulmonary resuscitation (CPR) to palpate a pulse can reduce the CCF. Peripheral Intravenous Analysis (PIVA) is a novel method for determining cardiac and volume status using waveforms from a standard peripheral intravenous (IV) line. We hypothesize that PIVA will demonstrate the onset of return of spontaneous circulation (ROSC) without interruption of CPR. Methods: Eight Zucker Diabetic Fatty (ZDF) rats (4 lean, 4 diabetic) were intubated, ventilated, and cannulated with a 24g IV in the tail vein and a 22g IV in the femoral artery, each connected to a TruWave pressure transducer. Mechanical ventilation was discontinued to achieve CA. After 8 minutes, CPR began with mechanical ventilation, IV epinephrine, and chest compressions using 1.5 cm at 200 times per minute until mean arterial pressure (MAP) increased to 120 mmHg per arterial line. All waveforms were recorded and analyzed in LabChart. PIVA was measured using a Fourier transform of the peripheral venous waveform. Data are mean ± SD. Statistics: Unpaired student’s t-test (two-tailed), α = 05. Results: CA and ROSC were achieved in all 8 rats. Within 1 minute of CPR, there was a 70 ± 35 fold increase/decrease in PIVA during CPR that was temporally associated with ROSC. Within 8 ± 13 seconds of a reduction in PIVA, there was a rapid increase in end-tidal CO 2 . In all rats, ROSC occurred within 38 ± 9 seconds of the maximum PIVA value. Peripheral venous pressure decreased by 1.2 ± 0.9 mmHg during resuscitation and ROSC, which was not significant different at p=0.05. Conclusion: In this pilot study, PIVA detected ROSC without interrupting CPR. Use of PIVA may obviate the need pause CPR for pulse checks, and may result in a higher CCF and survival. Future studies will focus on PIVA and CPR efficacy.

Sedative depth on neurological outcomes in a juvenile rat model of cardiopulmonary resuscitation

The guidelines for cardiopulmonary resuscitation (CPR) in pediatric advanced life support suggest that midazolam is the preferred agent for sedation in patients with mild hypothermia, whereas children with cardiac arrest (CA) are at a crucial stage regarding their immature nervous system. Studies have shown that midazolam may have a detrimental effect on the developmental of the pediatric nervous system. Our previous study found that midazolam induced neuronal damage after CPR in young rats. It is speculated that: midazolam causes the potential injury of neurons by inhibiting mitochondrial autophagy expression and is an important factor for the poor prognosis in children after successful CPR. This project intends to adopt the modified asphyxiant CPR model in juvenile rats. Survival rate, neurological function and histopathological changes were evaluated to determine the protective effects of appropriate sedation depth on cerebral ischemia-reperfusion injury in juvenile rats after CPR. Combined with cell biology and molecular biology related technologies, the mechanism by which the mitochondrial pinkl-parkin signaling pathway induces autophagy to inhibit neuronal apoptosis may be key factor in the protective effects of sedation depth on the brain. The aim of this study is to provide experimental evidence and elucidate the mechanisms of improvement of cerebral ischemia-reperfusion injury by sedation depth in children after successful CPR and to lay a theoretical and experimental basis for clinical treatment.

Effects of Polyethylene Glycol-20k on Postresuscitation Myocardial and Cerebral Function in a Rat Model of Cardiopulmonary Resuscitation.

Polyethylene glycol-20k is a hybrid cell impermeant that reduces ischemia injury and improves microcirculatory flow during and following low flow states through nonenergy-dependent water transfer in the microcirculation. We investigated the effects of polyethylene glycol-20k on postresuscitation microcirculation, myocardial and cerebral function, and duration of survival in a rat model of cardiopulmonary resuscitation. Ventricular fibrillation was induced in 20 male Sprague Dawley rats and untreated for 6 minutes. Animals were randomized into two groups (n = 10 for each group): polyethylene glycol-20k and control. Polyethylene glycol-20k (10% solution in saline, 10% estimated blood volume) and vehicle (saline) were administered at the beginning of cardiopulmonary resuscitation by continuous IV infusion. Resuscitation was attempted after 8 minutes of cardiopulmonary resuscitation. University-Affiliated Research Laboratory. Sprague Dawley Rats. Polyethylene glycol-20k. Buccal microcirculation was measured at baseline, 1, 3, and 6 hours after return of spontaneous circulation using a side-stream dark-field imaging device. Myocardial function was measured by echocardiography at baseline and every hour postresuscitation for 6 hours. The animals were then returned to their cage and observed for an additional 72 hours. Neurologic Deficit Scores were recorded at 24, 48, and 72 hours after resuscitation. Postresuscitation ejection fraction, cardiac output, and myocardial performance index were significantly improved in animals treated with polyethylene glycol-20k (p < 0.05). Perfused buccal vessel density and microcirculatory flow index values were significantly higher at all time points in the polyethylene glycol-20k group compared with the control group. Postresuscitation cerebral function and survival rate were also significantly improved in animals that received polyethylene glycol-20k. Administration of polyethylene glycol-20k following cardiopulmonary resuscitation improves postresuscitation myocardial and cerebral function, buccal microcirculation, and survival in a rat model of cardiopulmonary resuscitation.

Abstract 262: Hemodynamically-Guided Optimum Chest Compression Point in a Rat Model of Cardiopulmonary Resuscitation

Introduction: CPR aims to re-establish blood flow by chest compression (CC), achieving threshold levels of coronary perfusion pressure (CPP). For this, current guidelines recommend the lower sternal half as optimum CC point. However, this point might be not optimal for every individual. We investigated the hemodynamics generated by CC performed on different chest points in a rat model of CPR. We hypothesized that a CC point hemodynamically-identified would be a better approach compared to the lower sternal half. Methods: Ten male rats were anesthetized and arterial and right atrial pressures monitored. Ventricular fibrillation was induced and untreated for 8 min. CPR, including mechanical CC, ventilation, and epinephrine, was then performed for 8 min. Animals were divided to receive CC performed either on the lower sternal half (standard (STD), n=5) or on an optimum point identified as the one able to generate the maximum CPP (MaxCPP group, n=5). Cardiac districts involved in CC were subsequently identified by computed tomography (CT). Results: STD CC produced a CPP that was constantly below the threshold for successful resuscitation and trended to decrease over time. When the optimum CC point was identified hemodynamically, the CPP generated was constantly &gt; 20 mmHg. Indeed, CPP was significantly higher in the MaxCPP group compared to the STD one for the whole 8 min of CPR (p&lt;0.01, Fig). Moreover, administration of epi rapidly further improved CPP (p&lt;0.01 vs. pre-epi) in the group with an optimized CC point, while no drug effect was observed in the STD one. CT scan showed that the lower sternal half did not correspond to the LV maximum diameter, known to account for a maximum stroke volume generation during CC (Fig). Conclusion: Standard lower sternal half CC point is not able to maximize hemodynamics during CPR, making ineffective CC efforts and vasopressor administration. The quality of CPR may improve if the optimum CC point is identified as a reflection of CPP generated.

Improved Outcomes of Cardiopulmonary Resuscitation in Rats Treated With Vagus Nerve Stimulation and Its Potential Mechanism.

Studies have demonstrated that vagus nerve stimulation (VNS) reduces ischemia/reperfusion injury. In this study, we investigated the protective effects of VNS in a rat model of cardiopulmonary resuscitation (CPR). We further investigated whether the beneficial effects of VNS were dependent on the alpha 7 nicotinic acetylcholine receptor (α7nAChR). Forty animals were randomized into four groups and all underwent CPR (n = 10 each): CPR alone (control); VNS during CPR; α7nAChR antagonist methyllycaconitine citrate (MLA) with VNS; α7nAChR agonist 3-(2, 4-dimethoxybenzylidene) anabaseine (GTS-21 dihydrochloride) without VNS. The right vagus nerve was exteriorized in all animals. Ventricular fibrillation was induced and untreated for 8 min. Defibrillation was attempted after 8 min of CPR. VNS was initiated at the beginning of precordial chest compressions and continued for 4 h after return of spontaneous circulation (ROSC) in both the VNS and MLA groups. Hemodynamic measurements and myocardial function, including ejection fraction and myocardial performance index, were assessed at baseline, 1 and 4 h after ROSC. The neurological deficit score was measured at 24-h intervals for a total of 72 h. The heart rate was reduced in the VNS and MLA groups, while no difference was found in mean arterial pressure between the four groups. Better post-resuscitation myocardial and cerebral function and longer duration of survival were observed in the VNS-treated animals. The protective effects of VNS could be abolished by MLA and imitated by GTS-21. In addition, VNS decreased the number of electrical shocks and the duration of CPR required. VNS improves multiple outcomes after CPR.

Quercetin protects against inflammation, MMP‑2 activation and apoptosis induction in rat model of cardiopulmonary resuscitation through modulating Bmi‑1 expression.

With extensive pharmacological actions, quercetin has anti‑oxidant, free radical scavenging, anti‑tumor, anti‑inflammatory, anti‑bacterial and anti‑viral activity. Quercetin also reduces blood glucose and reduces high blood pressure, and has immunoregulation and cardiovascular protection functions. Additionally, it has been reported that it can reduce depression. The current study evaluated whether quercetin protects against inflammation, matrix metalloproteinase‑2 (MMP‑2) activation and apoptosis induction in a rat model of cardiopulmonary resuscitation (CPR), and whether Bmi‑1 expression was involved in the effects. In CPR model rats, treatment with quercetin significantly recovered left ventricular ejection fraction, left ventricular fractional shortening, ejection fraction (%), and left ventricle weight/body weight. Treatment with quercetin significantly inhibited ROS generation, inflammation and MMP‑2 protein expression in the rat model CPR. Finally, quercetin significantly suppressed caspase‑3 activity and activated Bmi‑1 protein expression in the rat model of CPR. The results demonstrated that quercetin protects against inflammation, MMP‑2 activation and apoptosis induction in a rat model of CPR, and that this may be mediated by modulating Bmi‑1 expression.

Gynostemma pentaphyllum is neuroprotective in a rat model of cardiopulmonary resuscitation.

Asphyxial cardiac arrest (ACA)-induced ischemia results in acute and delayed neuronal cell death. The early reperfusion phase is critical for the outcome. Intervention strategies directed to this period are promising to reduce ACA/resuscitation-dependent impairments. This study focused on the evaluation of the protective potential of an extract from Gynostemma pentaphyllum (GP), a plant used in traditional medicine with antioxidative, glucose lowering and neuroprotective activities, in an ACA rat model. We tested the following parameters: i) Basic systemic parameters such as pCO2 and blood glucose value within the first 30 min post-ACA; ii) mitochondrial response by determining activities of citrate synthase, respiratory chain complexes I + III and II + III, and the composition of cardiolipin 6 and 24 h post-ACA; iii) neuronal vitality of the CA1 hippocampal region by immunohistochemistry 24 h and 7 days post-ACA; and iv) cognitive function by a novel object recognition test 7 days post-ACA. GP, administered after reaching spontaneous circulation, counteracted the following: i) ACA-mediated increases in arterial CO2 tension and blood glucose values; ii) transient increase in the activity of the respiratory chain complexes II + III; iii) elevation in cardiolipin content; iv) hippocampal CA1 neurodegeneration, and v) loss of normal novelty-object seeking. The protective effects of GP were accompanied by side effects of the vehicle DMSO, such as the stimulation of citrate synthase activity in control animals, inhibition of cardiolipin synthesis in ACA animals and complex II + III activity in both control and ACA animals. The results emphasize the importance of the early post-resuscitation phase for the neurological outcome after ACA/resuscitation, and demonstrated the power of GP substitution as neuroprotective intervention. Moreover, the results underline the need of a careful handling of the popular vehicle DMSO.

Hypertonic saline infusion suppresses apoptosis of hippocampal cells in a rat model of cardiopulmonary resuscitation

Hypertonic saline (HS) attenuates cerebral edema, improves microcirculation perfusion and alleviates inflammation. However, whether the beneficial effect of HS on neurological function after cardiopulmonary resuscitation (CPR) in rat model of asphyxial cardiac arrest (CA) is mediated via attenuating apoptosis of neurons is not known. We studied the neuroprotective effect of HS in rats after CA and CPR, and explored the likely underlying mechanisms. Animals were randomly assigned to 4 equal groups (n = 15 each) according to the different infusions administered during resuscitation: control (C), normal saline (NS), hypertonic saline (HS), and hydroxyethyl starch (HES) groups. NDS at 12, 24, 48 and 72 h post-ROSC in the HS group were significantly higher than those in the NS and HES groups. Western blot analysis demonstrated a significant increase in Bcl-2 expression in HS, as compared to that in the NS and HES groups. However, Bax and Caspase-3 expressions in HS were significantly lower than that in the NS and HES groups. The apoptosis rate in HS was significantly lower than that in the NS and HES groups, suggesting HS treatment during resuscitation could effectively suppress neuronal cell apoptosis in hippocampal CA1 post-ROSC and improve neuronal function.

Abstract 12145: Remote Ischemic Preconditioning Regulates Post-resuscitation Microcirculation via A K Atp Channel-dependent Mechanism in a Rat Model of Cardiac Arrest

Introduction: Remote ischemic preconditioning (RIPC) provides potent protection to tissue microcirculation against ischemic-reperfusion injury. However, the underlying microvascular mechanism of RIPC is not fully understood. The present study investigated whether the protective effects of RIPC on microcirculation and myocardial function after cardiopulmonary resuscitation (CPR) are related to K ATP channel activation. Hypothesis: RIPC-induced activation of the K ATP channel would result in improved microcirculation and myocardial function following resuscitation. Methods: Twenty-four male Sprague-Dawley rats were randomized into three groups (n=8 for each group): RIPC, RIPC with K ATP channel blocker, and control. Remote ischemic preconditioning was induced by four cycles of 5 min of limb ischemia followed by 5 minutes of reperfusion. Ventricular fibrillation was induced and untreated for 8 min followed by 8 min of CPR. The animals were monitored for 6 h and observed for an additional 66 h. Sublingual microcirculation was assessed by a sidestream dark-field imaging device, and myocardial function was measured by echocardiography at baseline, 30 min, 1 h, 2 h, 4 h, and 6h post-resuscitation. Results: At 30 min and subsequent intervals post-resuscitation, both perfused vessel density and microcirculatory flow index were significantly greater in the RIPC group than in the control group ( P &lt; 0.05). Compared with the control group, a significantly higher ejection fraction, myocardial performance index, and greater duration of survival were observed in the RIPC group ( P &lt; 0.05). Pretreatment with the K ATP channel blocker (glibenclamide) significantly reversed the microvasucular and myocardial protective effects of RIPC ( P &lt; 0.05) (Figure 1, 2). Conclusions: In a rat model of CPR, the beneficial effect of RIPC on sublingual microcirculation and cardiac function with improved survival was related, at least in part, to the activation of K ATP channel.

Effects of Oxygen Concentrations on Postresuscitation Myocardial Oxidative Stress and Myocardial Function in a Rat Model of Cardiopulmonary Resuscitation.

Lipid peroxidation induced by free-radical species plays a prominent role in myocardial injury following ischemia and reperfusion. However, there is a lack of data in different oxygen concentrations on myocardial lipid peroxidation during the early phase of reperfusion. In this study, we investigated whether ventilation with medium or normal concentration of oxygen would decrease the severity of myocardial lipid peroxidation and postresuscitation myocardial dysfunction. Prospective, randomized, controlled experimental study. University-affiliated animal research institution. Sixty-three healthy male Sprague-Dawley rats. Animals were randomized into three groups: 1) 100% group, 2) 50% group, and 3) 21% group. Ventricular fibrillation was induced and untreated for 8 minutes, and defibrillation was attempted after 8 minutes of cardiopulmonary resuscitation. Ventilation with 100%, 50%, or 21% oxygen was initiated in all groups during cardiopulmonary resuscitation and 1 hour following the return of spontaneous circulation. Normoxic ventilation was maintained thereafter. Myocardial function, including ejection fraction and myocardial performance index, were measured at baseline, 4, or 72 hours after resuscitation. Blood samples were drawn at baseline, 15 minutes, 1, 4, or 72 hours after resuscitation for the measurements of blood gas or biomarkers. Significantly better myocardial function and longer duration of survival were observed in the 50% group. Compared with the 21% and 100% groups, a mild hyperoxia and greater oxygen extraction with lower 8-iso-prostaglandin F2α were observed in the 50% group. Pearson correlation analysis confirmed that 8-iso-prostaglandin F2α was positively correlated with myocardial performance index at 4 hours postresuscitation. In a rat model of cardiac arrest and resuscitation, ventilation with 50% inspired oxygen during early postischemic reperfusion phase contributed to a decreased lipid peroxidation and a better myocardial function and duration of survival.

Abstract 10458: Improved Outcomes of Cardiopulmonary Resuscitation in Rats Treated With Vagus Nerve Stimulation Through Cholinergic Anti-Inflammatory Pathway

Introduction: Studies have demonstrated that vagus nerve stimulation (VNS) reduces ischemia reperfusion (I/R) injury. In this study, we investigated the protective effects of VNS in a rat model of cardiopulmonary resuscitation (CPR). We further investigated whether the beneficial effects of VNS were dependent on the alpha 7 nicotinic acetylcholine receptor (α7nAChR). Methods: The animals were randomized into 4 groups (n=10 each): (1) CPR group (n=10): the rats underwent 8 mins of untreated ventricular fibrillation (VF) followed by 8 mins of CPR and defibrillation. The right vagus nerve was exteriorized but not stimulated.; (2) VNS group (n=10): the treatment was identical to the CPR group except that VNS was initiated at the beginning of precordial compression and continued for 4 hours after the return of spontaneous circulation(ROSC); (3) MLA group(n=10): the treatment was identical to the VNS group except that α7nAChR antagonist MLA (5mg/kg) was administered intraperitoneally (IP) 15 mins prior to VF; (4) GTS group(n=10): the treatment was identical to the CPR group except that α7nAChR agonist GTS-21 (5mg/kg) was IP injected 30 mins before VF. Blood gases, post resuscitation myocardial and cerebral function and the duration of survival were monitored in all animals. Results: There were no differences in mean arterial pressure among 4 groups. Significantly better post-resuscitation myocardial and cerebral functions and longer durations of survival were observed in VNS-treated animals, and these protective effects of VNS could be abolished by MLA and imitated by GTS-21 indicating that these beneficial effects might be dependent on a7nAChR (Figure *P&lt;0.05 vs CPR, **P&lt;0.01 vs CPR, ##P&lt;0.01 vs MLA). In addition, VNS decreased the number of electric shocks and the length of CPR duration. Conclusion: VNS improves the outcomes after CPR and cholinergic anti-inflammatory pathway via α7nAChR plays an important role during CPR.

Evaluation of cyclosporine a as a cardio- and neuroprotective agent after cardiopulmonary resuscitation in a rat model.

The immunosuppressant drug cyclosporine A (CsA) is a direct inhibitor of the mitochondrial permeability transition pore, which is the common end point of many pathways of ischemic preconditioning and postconditioning. We studied the neuroprotective and cardioprotective effect of CsA after cardiac arrest (CA) in a rat model of cardiopulmonary resuscitation. After institutional approval by the Governmental Animal Care Committee, 83 rats were subjected to 6 min of CA and were randomly and investigator-blinded allocated either to placebo (n = 15) or interventional group (n = 15; 10-mg/kg body weight CsA intravenously) after restoration of spontaneous circulation (ROSC). Before CA (baseline) as well as 1 h and 3 h after ROSC, continuous measurement of stroke volume, left ventricular ejection fraction, preload adjusted maximum power, and end diastolic volume was performed using a conductance catheter. One day, 3 days, and 7 days after ROSC, neurological outcome was evaluated by a tape removal test. After 7 days of reperfusion, coronal brain sections were analyzed by counting Nissl-positive (i.e., viable) neurons and terminal deoxynucleotidyl transferase dUTP nick end labeling positive (i.e., apoptotic) cells. Animals treated with CsA had a higher stroke volume (96 [93; 107] μL vs. 78 [73; 94] μL; P = 0.02), higher ejection fraction (58% [51%; 63%] vs. 42% [35%; 51%]; P = 0.002), and higher preload adjusted maximum power (4.8 [3.9; 6.1] vs. 2.3 [2.0; 2.6] mW/μL; P < 0.001). End diastolic volume remained stable in the CsA group 3 h after ROSC in comparison to baseline (160 [143; 181] μL vs. 157 [148; 192] μL; P = 0.56), whereas it increased in the placebo group (169 [153; 221] μL vs. 156 [138; 166] μL, P = 0.05). More neurons survived after administration of CsA (2.5 [1.6; 4.9] vs. 0.7 [0.4; 1.4]; P = 0.005). Compared to placebo-treated animals, the time in the tape removal test 7 days after ROSC was reduced by half in the CsA group without reaching statistical significance (26 [22; 51] vs. placebo 53 [38; 56] s; P = 0.13). Cyclosporine A treatment neither affected the number of terminal deoxynucleotidyl transferase dUTP nick end labeling-positive cells nor the survival rate. Pharmacological postconditioning with CsA after successful cardiopulmonary resuscitation attenuates myocardial dysfunction and reduces neuronal damage.

Abstract 147: Cyclosporine a as a Neuro- and Cardioprotective Agent After Cardiopulmonary Resuscitation in a Rat Model

Background: The immunosuppressant drug cyclosporine A (CsA) is a direct inhibitor of the mitochondrial permeability transition pore which is the common end point of many pathways of ischaemic pre- and postconditioning. We studied the neuro- and cardioprotective effect of CsA after cardiac arrest (CA) in a rat model of cardiopulmonary resuscitation. Methods and Results: Following institutional approval by the Governmental Animal Care Committee rats were subjected to 6 min of CA and were randomly and investigator-blinded allocated either to placebo (n=15) or interventional group (n=15, 10 mg/kg body weight CsA intravenously) after restoration of spontaneous circulation (ROSC). Before CA (baseline) as well as 1 h and 3 h after ROSC, continuous measurement of stroke volume (SV), ejection fraction (EF), preload adjusted maximum power (PAMP) and end diastolic volume (EDV) was performed using a conductance catheter. One day, 3 days, and 7 days after ROSC neurological outcome was evaluated by a tape removal test. After seven days of reperfusion coronal brain sections were analyzed by counting Nissl-positive (i.e. viable) neurons and TUNEL-positive (i.e. apoptotic) cells. Animals treated with CsA had a higher SV (96 [93; 107] vs. 78 [73; 94] μl, p=0.02), higher EF (58 [51; 63] vs. 42 [35; 51] %, p=0.002), and higher PAMP (4.8 [3.9; 6.1] vs. 2.3 [2.0; 2.6] mW/μl 2 , p&lt;0.001). EDV remained stable in the CsA group 3 h after ROSC in comparison to baseline (160 [143; 181] vs. 157 [148; 192] μl, p=0.56), whereas it increased in the placebo group (169 [153; 221] vs. 156 [138; 166] μl, p=0.05). More neurons survived after administration of CsA (2.5 [1.6; 4.9] vs. 0.7 [0.4; 1.4] Nissl-positive cells/100 pixel; p=0.005). Animals in the CsA group needed less than half of the time in the tape removal test 7 days after ROSC than placebo treated animals without reaching statistical significance (26 [22; 51] vs. placebo 53 [38; 56] s; p=0.13). CsA treatment did not affect number of TUNEL-positive cells and survival rate. Conclusion: Pharmacological treatment with CsA after successful CPR attenuates myocardial dysfunction and reduces neuronal damage.

Expression of tumor necrosis factor-α-induced protein 6 after transplantation of mesenchymal stem cells in a rat model of cardiopulmonary resuscitation

Objective To investigate the effects of bone marrow mesenchymal stem cells (MSCs)treatment on TSG-6 in a rat model of cardiopulmonary resuscitation (CPR).Methods Sprague Dawley (SD) rats were randomly (random number) divided into sham group,phosphate buffer solution (PBS)-treated group and MSCs-treated group.Animals were subjected to asphyxial cardiac arrest followed by CPR.In PBS-treated group or MSCs-treated group,animals were injected intravenously with PBS or MSCs at 2h after resuscitation.Neurological deficit scores (NDS) were assessed at 1,3 and 7 d after CPR.Serum S-100B was assayed using enzyme linked immunosorbent assay (ELISA).Immunofluorescence was performed to detect donor MSCs and the expression of TSG-6 in brain.TSG-6 and proinflammatory cytokines in brain were assayed using real time reverse transcription-polymerase chain reaction (RT-PCR).Western blot analysis was performed to measure the levels of neutrophil elastase (NE) in brain.Multiple comparisons were made by analysis of variance.Results At 3d and 7d,MSCs-treated group demonstrated higher NDS than PBS-treated group (P ＜ 0.01),and serum S-100B levels significantly reduced in MSCs-treated group compared with PBS-treated group (P ＜ 0.01).DAPI-labeled MSCs migrated into the ischemic brain and some DAPI + cells colocalized with TSG-6.Compared with PBS-treated group,MSCs treatment significantly up-regulated the expression of TSG-6 and reduced the expression of NE and proinflammatory cytokines in brain at 3 d and 7 d after CPR (P ＜ 0.05).Conclusion Systemically administered MSCs suppressed inflammatory responses in brain after CPR and improved neurological function in rats possibly via induction of TSG-6. Key words: Cardiac arrest ; Cardiopulmonary resuscitation ; Mesenchymal stem cells ; Inflammation; Neurological deficit scores; S-100B; Proinflammatory cytokines; Tumor necrosis factor-α-induced protein 6

Voxel-based morphometry and histological analysis for evaluating hippocampal damage in a rat model of cardiopulmonary resuscitation

Cardiac arrest and subsequent cardiopulmonary resuscitation (CPR) induce hippocampal damage, which has been identified using histological analysis of post-mortem brains. Voxel-based morphometry (VBM), an in-vivo assessment of regional differences in the concentration or volume of a particular tissue such as gray matter, has revealed CPR-induced decreases in gray matter in the hippocampus, where histopathological findings were observed. However, the potential link between the changes in gray matter detected by VBM and hippocampal damage has not been investigated directly. In this study, we compared results obtained using VBM directly to results from histological analyses in the same CPR rat brains, which exhibited neuronal loss and microglial invasion in the CA1 region of the hippocampus (CA1). T2-weighted images were obtained and preprocessed for VBM to produce gray matter concentration (GMC) maps in rats with asphyxia-induced cardiac arrest and CPR and sham-operated controls (n=12 each). Brains were fixed, and the number of neurons and microglia in CA1 were counted. VBM revealed a significant decrease in GMC in CPR rats compared to sham-operated controls. The CPR-induced decrease in GMC was localized to CA1, which is the same brain region where neuronal loss and microglial invasion were noted in response to CPR. GMC values were positively correlated with the number of neurons and tended to be negatively correlated with the number of microglia in CA1 of CPR rats. In conclusion, these results indicate that VBM-detected alterations in gray matter can be used as a surrogate marker for hippocampal damage following CPR.