Shen-fu injection attenuates postresuscitation myocardial dysfunction in a porcine model of cardiac arrest

To investigate the effect of Shen-Fu injection (SFI) for the management of postresuscitation myocardial dysfunction in a porcine model of cardiac arrest. Ventricular fibrillation was induced electrically in anesthetized domestic swine. After 4 min of untreated ventricular fibrillation, cardiopulmonary resuscitation was initiated. Sixteen successfully resuscitated pigs were randomized to receive a continuous infusion of either SFI (0.24 mg/min) or saline placebo for 6 h, beginning 15 min after return of spontaneous circulation (ROSC). The SFI treatment produced better left ventricular +dP/dtmax, -dP/dtmax, cardiac output, and ejection fraction after ROSC. The SFI treatment also produced lower serum cardiac troponin I, lactate levels, and left ventricle malondialdehyde content after ROSC, whereas left ventricle superoxide dismutase, Na-K-ATPase, and Ca-ATPase activity were significantly increased in the SFI group when compared with saline group. The cardioprotective effect of SFI was further confirmed by myocardial ultrastructure examination. Shen-Fu injection can attenuate postresuscitation myocardial dysfunction through beneficial effects on energy metabolism and remarkable antioxidant capacity.     

Shen-fu injection attenuates postresuscitation lung injury in a porcine model of cardiac arrest

ObjectiveTo investigate the effects of Shen-Fu injection (SFI) on postresuscitation lung injury in a porcine model of cardiac arrest.MethodsTwenty-four anaesthetised male Landrace pigs were subjected to 4 min of untreated ventricular fibrillation (VF), followed by standard cardiopulmonary resuscitation. Sixteen successfully resuscitated pigs were randomised into two groups (eight pigs per group); one group received an SFI infusion and the other group received a normal saline infusion, at an infusion rate of 0.24 mg/min from 15 min after the return of spontaneous circulation (ROSC) until 6 h after ROSC.ResultsOxygenation index, respiratory index, oxygen delivery, oxygen consumption, oxygen extraction, dynamic lung compliance, airway resistance, external vascular lung water index, and pulmonary vascular permeability index at 15 min, 30 min, 1 h, 2 h, 4 h, and 6 h after ROSC were all worse than baseline in the saline group, and were all better in the SFI group than in the saline group. The pulmonary protective effects of SFI were further confirmed by histopathological and ultrastructural observations of lung tissue. SFI infusion resulted in lower apoptosis index, caspase-3 protein expression, and malondialdehyde content of lung tissue after ROSC, and increased Bcl-2 protein expression and superoxide dismutase, Na⁺-K⁺-ATPase, and Ca²⁺-ATPase activity compared with the saline group.ConclusionShen-Fu injection can attenuate postresuscitation lung injury through suppression of lung cell apoptosis and improvement of energy metabolism and antioxidant capacity.     

Apoptosis is involved in the mechanism of postresuscitation myocardial dysfunction in a porcine model of cardiac arrest

Background

Postresuscitation myocardial dysfunction contributes to the low survival rate after successful resuscitation, but its mechanism remains poorly understood. This study investigated whether caspase 3–mediated apoptosis is activated in the heart after postresuscitation myocardial dysfunction.

Methods

After pigs were subjected to 8 minutes of electrically induced cardiac arrest (CA), standard cardiopulmonary resuscitation was performed. Animals in the post–return of spontaneous circulation (ROSC) group were randomly assigned to be killed (n = 6 per group) at 12 and 24 hours after ROSC, and myocardial specimens were analyzed with electron microscopy, Western blotting, quantitative real-time polymerase chain reaction, and terminal deoxynucleotidyl transferase–mediated dUTP nick end labeling assay.

Results

Myocardial function was significantly impaired after ROSC. Expression of Bcl-2, Bax, and caspase 3 protein was markedly increased in the post-ROSC group compared with the sham-operated group (P < .05) at 12 and 24 hours after ROSC, whereas Bcl-2/Bax was significantly reduced in the post-ROSC group compared with the sham-operated group (P < .05). The messenger RNA levels of caspase 3 were significantly elevated at 12 and 24 hours after ROSC, and increases in caspase 3 activity indicated activation of the mitochondrial apoptotic pathway. Typical apoptotic nuclei were observed in cardiomyocytes 24 hours after ROSC. More apoptotic cells were observed in animals that had undergone CA compared with sham-operated animals (P < .05).

Conclusion

Caspase 3–mediated apoptosis may be one of the main pathologic mechanisms of postresuscitation myocardial injury in a porcine model of CA.     

Effect of Shenfu on inflammatory cytokine release and brain edema after prolonged cardiac arrest in the swine

Objective

Shenfu injection (SFI), a traditional Chinese formulation, has been confirmed to be protective against brain during ischemia and reperfusion injury. In this exploratory study, we investigated the action of SFI in regulating the inflammatory response and brain edema after cardiopulmonary resuscitation.

Methods

After 8 minutes of untreated ventricular fibrillation (VF), pigs in the cardiopulmonary resuscitation group (n = 24) received a central venous injection of either SFI (SFI group; 1.0 mL/kg), epinephrine (EP group; 0.02 mg/kg), or saline (SA group). Levels of porcine-specific tumor necrosis factor α and interleukin in sera were measured using enzyme-linked immunosorbent assay at 0.5, 1, 2, 4, 6, and 24 hours after return of spontaneous circulation (ROSC). Surviving pigs were killed 24 hours after ROSC, and the brains were removed for electron microscopy, Western blotting, and quantitative real-time polymerase chain reaction analysis.

Results

Compared with the EP and SA groups, SFI decreased the levels of tumor necrosis factor α and interleukin-6 in serum and the brain (P < .05) and decreased the expression of nuclear factor κB and aquaporin-4 messenger RNA in the brain (P < .05). Shenfu injection also inhibited the expression of nuclear factor κB, matrix metalloproteinase 9, and aquaporin-4 protein after ROSC (P < .05). Observation of brain tissue ultrastructure showed that injury was alleviated in the SFI group compared with the SA and EP groups.

Conclusions

Our exploratory experiments demonstrated that SFI reduced cerebral damage in a porcine model of VF, which may be related to suppression of the inflammatory reaction and decreased brain edema after ROSC.     

Caspase-3–mediated splenic lymphocyte apoptosis in a porcine model of cardiac arrest

Background

Postresuscitation immunologic dysfunction contributes to the low survival rate after successful resuscitation, but its mechanism remains poorly understood. The mitochondrial apoptosis pathway is initiated by the Bcl-2/Bax-controlled and caspase-3–mediated pathway, this study investigated whether mitochondrial pathway-mediated splenic lymphocyte apoptosis is involved in the postresuscitation immunosuppression in a porcine model of cardiac arrest.

Methods

Twenty-eight Wuzhishan miniature pigs were randomly divided into 2 groups: return of spontaneous circulation (ROSC; n = 22) and sham-operated (n = 6). Return of spontaneous circulation was initiated after 8 minutes of untreated ventricular fibrillation. After successful ROSC, CD4⁺ and CD8⁺ lymphocyte subsets were determined by flow cytometry. Surviving pigs were randomly assigned to be humanely killed at 24 and 72 hours after ROSC (n = 8 per group). Spleens were removed for histopathologic analysis, Western blotting, quantitative real-time polymerase chain reaction, and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling assay.

Results

A high degree of splenic lymphocyte apoptosis was observed in the ROSC group. Expression of Bax and activated caspase-3 was markedly increased in splenic tissue, whereas Bcl-2 was significantly decreased in the post-ROSC group compared with the sham-operated group (P < .05) at 24 and 72 hours after ROSC. The messenger RNA levels of activated caspase-3 of splenic tissue were significantly elevated at 24 and 72 hours after ROSC.

Conclusion

These results demonstrates that Bcl-2/Bax and caspase-3–mediated mitochondrial apoptosis signaling pathway may contribute to abnormal splenic lymphocyte apoptosis, which may be one of the main pathologic mechanisms of postresuscitation disturbance of immunologic function in a porcine model of cardiac arrest.     

复苏后心功能不全犬的心肌组织病理学变化

目的:观察犬心跳骤停复苏后存在复苏后心功能不全的犬心肌组织的病理变化。方法:体外电击诱发犬室颤,3min后复苏,12只犬随机分为心肺复苏组(CPR组)和空白对照组,每组6只,采用Swan-Ganz漂浮导管监测复苏前后6h的平均动脉压(MAP)、心输出量(CO)和肺毛细血管楔压(PAWP),6h后取心肌组织,TUNEL法检测心肌组织凋亡的形态学改变以及心肌病理学检查。结果:MAP和CO在恢复自主循环后随时间延长而下降,6h降至最低,复苏后各观察点均低于空白对照组。CPR组心肌细胞凋亡指数明显高于空白对照组(P<0.01),CPR组心肌的病理损害大于空白对照组。结论:电击诱发室颤犬复苏成功后存在着心肌细胞的坏死和凋亡增加,可能是复苏后心功能不全的原因之一。     

Effects of the specific bradycardic agent zatebradine on hemodynamic variables and myocardial blood flow during the early postresuscitation phase in pigs

Cardiopulmonary resuscitation (CPR) leads to an excessive stimulation of the sympathetic nervous system that may result in tachycardia and malignant arrhythmias in the postresuscitation phase. The attenuation of this reaction by a specific bradycardic agent has not been compared to beta-blockade and placebo. After 4 min of ventricular fibrillation, and 3 min of CPR, 21 pigs were randomized to receive 45 microg/kg epinephrine in combination with either a specific bradycardic agent (0.5 mg/kg zatebradine; n = 7), or a beta-blocker (1 mg/kg esmolol; n = 7), or placebo (normal saline; n = 7). Two minutes after drug administration, defibrillation was performed to restore spontaneous circulation (ROSC). Hemodynamic variables, left ventricular contractility, right ventricular function, and myocardial blood flow were studied at prearrest, and for 3 h after ROSC. In comparison with esmolol and placebo, zatebradine resulted in a significant reduction in heart rate during the postresuscitation period, and reduced the number of premature ventricular contractions in the first 5 min after ROSC. This reduction in heart rate was associated with a significantly higher right ventricular ejection fraction, stroke volume, and endocardial/epicardial perfusion ratio at 5 min after ROSC. In comparison with placebo, esmolol administration decreased heart rate only moderately, but significantly reduced right ventricular stroke volume and cardiac output at 5 min after ROSC. Although only one dose and only one administration pattern of zatebradine has been investigated, we conclude that zatebradine administration during CPR effectively reduced heart rate without compromising myocardial contractility during the postresuscitation phase in pigs.     

窒息法和室颤法致猪心脏骤停后肺损伤的研究

目的 通过窒息和室颤的心脏骤停动物模型,对心肺复苏后肺损伤进行对照研究.方法 将近交系五指山小型猪随机(随机数字法)分为窒息组(AS)和室颤组(VF),每组各24只,分别采用阻塞气管插管和程控电刺激诱导方法制模,制模成功后给予标准的心肺复苏至ROSC,分别测量基础状态、ROSC即刻、15 min、30 min、1h、2h、4h和6h的氧合指数(OI)、呼吸指数(RI)、氧输送(DO2)、血乳酸,并监测同一时刻动物的肺顺应性(Cdyn)、气道阻力(Raw)、血管外肺水指数(EVLWI)和肺血管通透性指数(PVPI);于基础状态时和ROSC 4 h时进行肺核素灌注扫描和PET-CT扫描;ROSC后6h将动物处死后取肺组织进行病理及电镜检查,检测组织中Na+-K+-ATP酶、Ca2-ATP酶、SOD、MDA、Bcl-2、Bax及Caspase3蛋白水平及凋亡指数(AI％)等.结果 窒息组的ROSC率和6h生存率均显著低于室颤组(P＜0.01);在肺组织有关酶学及蛋白(Na+-K+-ATPase、Ca2-ATPase、SOD、MDA、AI％、Bax、Bcl-2和Caspase3)检测方面,窒息组重于室颤组,且凋亡现象更严重(P＜0.01);在呼吸力学各个时间点相关指标(OI、RI、DO2、血乳酸、Cdyn、Raw、EVLWI、PVPI)的监测中,窒息组的各项指标的变化较室颤组更明显,在6h后仍未能恢复至基础状态.窒息组和室颤组在肺灌注核素扫描上,无明显的充盈缺损;而在PET-CT扫描上则可见较明显的充盈缺损区.结论 心脏骤停后肺损伤的发生与导致心脏骤停的病因密切相关,窒息明显重于室颤,而心外按压不是导致此类肺损伤的主要原因.     

Naloxone Combined with Epinephrine Decreases Cerebral Injury in Cardiopulmonary Resuscitation

Background: Cardiopulmonary arrest is a serious disease that claims many lives every day; 30% of the patients suffer irreversible central nervous system injury after restoration of systemic circulation (ROSC). Objectives: Naloxone combined with epinephrine was tested in a cardiac arrest rat model in which asphyxia was induced to determine if this drug combination could increase the resuscitation rate (survival) and decrease the cerebral damage. Methods: Twenty-four male Wistar rats were randomly assigned to one of three groups: the group treated with 1 mL saline (SA group; n = 8), the group treated with only epinephrine 5 μg/100 g (EP group; n = 8), or the group treated with epinephrine 5 μg/100 g combined with naloxone 1 mg/kg (NA group; n = 8). Eight minutes after arrest, cardiopulmonary resuscitation was initiated and the different drugs were administered to the rats in their respective groups at the same time. Mean arterial pressure (MAP), heart rate (HR), and neurodeficit score (NDS) were measured. Results: The HR in the NA group (414 ± 45 beats/min) was faster than in the EP group (343 ± 29 beats/min) at the 5-min time point (P < 0.01). The HR in the NA group was 392 ± 44 beats/min and 416 ± 19 beats/min at the 60-min and 180-min time points, respectively. There were no statistically significant differences in MAP before or after ROSC. The rates of ROSC were 2 of 8, 6 of 8, and 7 of 8 animals in the SA group, EP group, and NA group, respectively. Three days later, the rates decreased to 1, 3, and 5 in the SA group, EP group, and NA group, respectively. The average resuscitation time in the NA group was significantly shorter than in the other two groups. The NDS in the NA group was 57 ± 13, higher than in the EP group (45 ± 13) and SA group (38). Conclusion: Naloxone combined with epinephrine significantly increased the resuscitation rate in a rat model. Furthermore, the combination of naloxone and epinephrine increased the NDS after cardiopulmonary resuscitation.     

Effects of vasopressin and epinephrine on splanchnic blood flow and renal function during and after cardiopulmonary resuscitation in pigs

OBJECTIVE: To compare the effects of vasopressin versus epinephrine on splanchnic blood flow during and after cardiopulmonary resuscitation (CPR), and to evaluate the effects of these vasopressors on renal function in the postresuscitation phase. DESIGN: Prospective, randomized laboratory investigation using an established porcine CPR model with instrumentation for continuous measurement of splanchnic and renal blood flow. SETTING: University hospital experimental laboratory. SUBJECTS: A total of 12 anesthetized, 12- to 16-wk-old domestic pigs weighing 30-35 kg. INTERVENTIONS: After 4 mins of cardiac arrest, and 3 mins of CPR, 12 pigs were randomly assigned to receive either 0.4 units/kg vasopressin (n = 6) or 45 microg/kg epinephrine (n = 6). Defibrillation was performed 5 mins after drug administration; all animals were observed for 6 hrs after return of spontaneous circulation (ROSC). MEASUREMENTS AND MAIN RESULTS: Mean +/- SEM superior mesenteric artery blood flow was significantly (p < .05) lower after vasopressin compared with epinephrine at 90 secs after drug administration (13+/-3 vs. 129+/-33 mL/min); at 5 mins after drug administration (31+/-18 vs. 155+/-39 mL/min); at 5 mins after ROSC (332+/-47 vs. 1087+/-166 mL/min); and at 15 mins after ROSC (450+/-106 vs. 1130+/-222 mL/min); respectively. Mean +/- SEM left renal and hepatic artery blood flow after ROSC was comparable in both groups ranging between 120-290 mL/min (renal blood flow), and 150-360 mL/min (hepatic blood flow), respectively. Median urine output after ROSC showed no difference between groups, and highest values (180-220 mL/hr) were observed in the first 60 mins after ROSC. Median calculated glomerular filtration rate showed no difference between groups with values ranging between 30 and 80 mL/min in the postresuscitation phase. Calculated fractional sodium excretion and osmolar relationship between urea and plasma indicated no evidence for renal tubular dysfunction. CONCLUSIONS: In the early postresuscitation phase, superior mesenteric blood flow was temporarily impaired by vasopressin in comparison with epinephrine. With respect to renal blood flow and renal function after ROSC, there was no difference between either vasopressor given during CPR. Vasopressin given during CPR did not result in an antidiuretic state in the postresuscitation phase.     

Levosimendan improves postresuscitation myocardial dysfunction after beta-adrenergic blockade

In earlier studies, we found that a nonselective beta-adrenergic blocking agent, propranolol, facilitated cardiac resuscitation, reduced postresuscitation myocardial ectopy, and improved postresuscitation survival. However, the potential adverse effects and specifically the negative inotropic actions of propranolol prompted our further investigation of the potential value of a non-beta-adrenergic inotropic drug, levosimendan, in conjunction with propranolol, for minimizing postresuscitation myocardial dysfunction after successful resuscitation from cardiac arrest. Ventricular fibrillation was induced and untreated for 7 minutes in 15 domestic pigs, which were divided into propranolol, propranolol plus levosimendan, and control groups. Propranolol was administered as a bolus dose of 0.1 mg/kg during cardiac arrest. Electrical defibrillation was attempted after 12 minutes of cardiac arrest including 5 minutes of precordial compression. Levosimendan was administered at 10 minutes after successful resuscitation in a dose of 20 microg/kg and followed by infusion of 0.4 microg/kg/min over the ensuing 220 minutes. Propranolol reduced energies or numbers of defibrillatory shocks and postresuscitation myocardial ectopy, and it improved postresuscitation myocardial dysfunction. When levosimendan was added, postresuscitation myocardial contractile function was improved even more.     

Comparison between dobutamine and levosimendan for management of postresuscitation myocardial dysfunction

OBJECTIVE: To investigate the effects of levosimendan, a nonadrenergic inotropic calcium sensitizer, in comparison with adrenergic dobutamine for the management of postresuscitation myocardial dysfunction following resuscitation from prolonged cardiac arrest. DESIGN: Randomized prospective animal study. SETTING: Animal research laboratory. SUBJECTS: Male Yorkshire-cross domestic pigs INTERVENTIONS: Ventricular fibrillation was induced in male domestic pigs weighing between 35 and 40 kg. Cardiopulmonary resuscitation, including precordial compression and mechanical ventilation, was started after 7 mins of untreated cardiac arrest. Electrical defibrillation was attempted after 5 mins of cardiopulmonary resuscitation. Each animal was successfully resuscitated without pharmacologic intervention. Resuscitated animals were randomized to treatment with levosimendan, dobutamine, or saline placebo. The inotropic agents or an equivalent volume of placebo diluents was administered 10 mins after restoration of spontaneous circulation. Levosimendan was administered in a loading dose of 20 microg.kg over 10 mins followed by a 220-min infusion of 0.4 microg.kg.min. Dobutamine was infused into the right atrium in an amount of 5 microg.kg.min. Treatment was continued for a total of 230 mins. MEASUREMENTS AND MAIN RESULTS: Levosimendan and dobutamine produced comparable increases in cardiac output. However, levosimendan produced significantly greater left ventricular ejection fraction and fractional area changes compared with dobutamine and saline placebo. CONCLUSIONS: Levosimendan has the potential of improving postresuscitation myocardial function. It is likely to serve as an alternative to dobutamine as an inotropic agent for management of postresuscitation myocardial dysfunction.     

A selective alpha(2)-adrenergic agonist for cardiac resuscitation

The effects of selective alpha(2)-adrenergic agonist alpha-methylnorepinephrine on the initial success of resuscitation and postresuscitation myocardial function were compared with nonselective alpha- and beta-adrenergic epinephrine in a swine model of cardiac arrest. Epinephrine, the primary pharmacological intervention in the treatment of cardiac arrest, improves immediate outcome. However, epinephrine increases the severity of myocardial dysfunction after cardiac resuscitation. Both inotropic and chronotropic actions provoke disproportionate increases in myocardial oxygen consumption by the ischemic heart, prompting this study, in which we hypothesized that a selective alpha(2)-adrenergic agonist, alpha-methylnorepinephrine (alpha-MNE), would moderate these adverse effects of epinephrine and minimize postresuscitation myocardial dysfunction. After 7 minutes of untreated ventricular fibrillation (VF) in 14 anesthetized male domestic pigs, precordial compression at a fixed rate of 80 compressions/min was begun, along with mechanical ventilation. Either alpha-MNE (100 microg/kg) or epinephrine (20 microg/kg) was administered as a bolus after 2 minutes of precordial compression. After an additional 4 minutes of precordial compression, defibrillation was attempted. Left ventricular systolic and diastolic function was quantitated with the use of transesophageal echo-Doppler imaging. Comparable increases in coronary perfusion pressure to 15 mm Hg were observed after the administration of both drugs. All animals were successfully resuscitated; epinephrine and alpha-MNE were equally quick in restoring spontaneous circulation after 7 minutes of untreated VF. Ejection fraction was reduced by 35% and 14% by epinephrine and alpha-MNE, respectively, after resuscitation. Epinephrine and alpha-MNE increased postresuscitation heart rate by 38% and 15%, respectively. Accordingly, significantly less postresuscitation impairment followed the administration of alpha-MNE. alpha-MNE, a selective alpha-adrenergic agonist, was as effective as epinephrine in restoring spontaneous circulation after 7 minutes of untreated VF in a porcine model for CPR and demonstrated lesser postresuscitation myocardial injury.     

纯氧与空气复苏对窒息新生大鼠心肌细胞凋亡及BCL-2,BAX蛋白表达的影响

目的：在建立新生大鼠窒息的动物模型基础上。比较纯氧与空气复苏对窒息新生大鼠心肌细胞凋亡及Bcl-2、Bax蛋白表达的影响。方法：采用SD新生大鼠建立窒息模型2．5h，并分组进行纯氧与空气复苏。实验分为正常对照组、纯氧复苏组（PO组）和空气复苏组（RA组），均在复苏后24h和72h取心肌组织，制成石蜡切片，HE染色光镜观察心肌组织病理变化，TUNEL法测定心肌细胞凋亡指数，免疫组织化学S-P法检测心肌组织Bcl-2、Bax蛋白的表达情况。结果：HE染色光镜观察，与正常对照组相比，PO组可见大部分心肌纤维肿胀，有少许断裂，心肌间质及小静脉明显淤血，RA组心肌纤维则表现明显的片状或灶性坏死。RA组心肌细胞凋亡指数明显高于PO组，且以24h升高最显著。PO组凋亡抑制基因Bcl-2表达高于RA组，RA组促凋亡基因Bax明显高于PO组。结论：空气复苏较纯氧复苏后心肌细胞凋亡更严重，且以复苏后24h最明显，空气复苏促进Bax基因的表达上调，纯氧复苏可使凋亡抑制基因Bcl-2表达上调，提示高浓度氧对窒息复苏后心肌有一定的保护作用     

Differences of postresuscitation myocardial dysfunction in ventricular fibrillation versus asphyxiation

PurposeThis study aims to characterize postresuscitation myocardial dysfunction in 2 porcine models of cardiac arrest (CA): ventricular fibrillation cardiac arrest (VFCA) and asphyxiation cardiac arrest (ACA).MethodsThirty-two pigs were randomized into 2 groups. The VFCA group (n = 16) were subject to programed electrical stimulation, and the ACA group (n = 16) underwent endotracheal tube clamping to induce CA. Once induced, CA remained untreated for 8 minutes. Two minutes after initiation of cardiopulmonary resuscitation (CPR), defibrillation was attempted until return of spontaneous circulation (ROSC) was achieved or animals died.ResultsReturn of spontaneous circulation was 100% successful in VFCA and 50% successful in ACA. Cardiopulmonary resuscitation duration in VFCA was about half as short as in ACA. The survival time of VFCA was significantly longer than that of ACA. Ventricular fibrillation cardiac arrest had better mean arterial pressure, cardiac output, and left ventricular ± dp/dt_max after ROSC than ACA. Echocardiography revealed significantly lower left ventricular ejection fraction in ACA than in VFCA. Myocardial perfusion imaging using single-photon emission computed tomography demonstrated that myocardial injuries after ACA were more severe and widespread than after VFCA. Under a transmission electron microscope, the overall heart morphologic structure and the mitochondrial crista structure were less severely injured in the VFCA group than in the ACA group. Moreover, the percentage of apoptotic cardiomyocytes was higher in ACA than in VFCA.ConclusionsCompared with VFCA, ACA causes more severe cardiac dysfunction associated with less successful resuscitation and shorter survival time.     

Tumor necrosis factor-alpha is associated with early postresuscitation myocardial dysfunction

OBJECTIVE: Left ventricular dysfunction after successful cardiopulmonary resuscitation contributes to early death following resuscitation. The stress-induced proinflammatory cytokines, particularly tumor necrosis factor-alpha and interleukin-1beta, are known to depress myocardial function. We hypothesized that tumor necrosis factor-alpha and interleukin-1beta, synthesized and released in response to the stress of global ischemia accompanying cardiac arrest, play a role in development of postresuscitation left ventricular dysfunction. METHODS: Hemodynamic variables, tumor necrosis factor-alpha , interleukin-1beta, interleukin-6 (enzyme-linked immunosorbent assay method), and ionized calcium were measured in ten anesthetized swine before and after 7 mins of cardiac arrest and during the early postresuscitation period (60-90 mins). RESULTS: Tumor necrosis factor-alpha increased three-fold within 15 mins of restoration of circulation and remained elevated throughout the observation period. A significant negative correlation was observed between tumor necrosis factor-alpha and left ventricular systolic change in pressure over time (r = -.54, p <.001). Interleukin-1beta was undetectable before and after resuscitation, and interleukin-6 was detectable in only two animals after resuscitation. Although a significant decline in ionized calcium was observed and correlated with left ventricular systolic change in pressure over time, an independent role for ionized calcium in postresuscitation left ventricular dysfunction was not demonstrated. CONCLUSION: Tumor necrosis factor-alpha increases during the early postresuscitation period and may play a role in postresuscitation myocardial dysfunction.     

胰岛素对心肺复苏大鼠神经元凋亡及Bcl-2,Bax mRNA表达的影响

目的 探讨脑室内注射胰岛素对心肺复苏(cardiopulmonary resuscitation,CPR)后大鼠海马CA1区神经元凋亡和对抑凋亡因子Bcl-2,促凋亡因子Bax mRNA表达的影响.方法 实验地点在首都医科大学宣武医院试验动物中心.30只雄性SD大鼠随机(随机数字法)分为假手术组(对照组,n=6)、心肺复苏组(复苏组,n=12)及CPR后胰岛素干预组(胰岛素组,n=12).经食道超速起搏诱发6min室颤制备大鼠CPR模型;以CPR后大鼠恢复室上性心率、收缩压超过60 mmHg(1 mmHg=0.133 kPa)并持续10 min以上,作为自主循环恢复(ROCS)标准;ROCS 10 min后,胰岛素组大鼠经立体定位仪定位,脑室内注射12.5 μL(1 U)胰岛素,其余2组大鼠注射等量生理盐水.维持生命体征,CPR后24,72 h,应用实时荧光PCR (Realtime-PCR)测定海马CA1区神经元Bcl-2,Bax mRNA的表达量;CPR后7d,应用TUNEL染色检测海马CA1区神经元凋亡;CPR前后监测大鼠静脉血糖变化.计量资料采用均数±标准差(-x±s),组间比较采用单因素方差分析(ANOVA);相关性统计应用Pearson相关分析,以P＜0.05为差异具有统计学意义.结果 ①CPR后24,72 h,胰岛素组大鼠Bcl-2 mRNA表达量均高于复苏组(1.45±0.05) vs.(0.79±0.01);(0.95±0.06) vs.(0.35±0.03),差异具有统计学意义(P＜0.01).组内比较发现,胰岛素组、复苏组72 h表达均低于24 h(P＜0.01).而胰岛素组与复苏组Bax mRNA表达差异无统计学意义(P＞0.05),胰岛素组、复苏组72 h与24h比较差异无统计学意义(P＞0.05).②CPR后7d,胰岛素组大鼠海马CA1区神经元凋亡计数,复苏组(124.75±17.35)个/mm2明显高于对照组(5.12±3.26)个/mm2和胰岛素组(92.79±7.49)个/mm2,差异具有统计学意义(P＜0.01).③各组大鼠各时间点外周静脉血糖比较无统计学意义(P＞0.05).结论 脑室内注射1U胰岛素,能够促进CPR后大鼠神经元促凋亡因子Bcl-2 mRNA的表达,抑制神经元凋亡,具有神经保护作用.脑室注射1U胰岛素不降低外周血糖.     

Ultrastructural evidence of mitochondrial abnormalities in postresuscitation myocardial dysfunction

Objectives

Though there is evidence to implicate that the mitochondrion may play an important role in the development of postresuscitation myocardial dysfunction, limited data are available regarding the ultrastructural alterations of the mitochondria, mitochondrial energy-producing ability, and their relationship to postresuscitation myocardial dysfunction. This study was designed to determine whether mitochondrial abnormalities contribute to the development of postresuscitation myocardial dysfunction.

Methods

Fifteen anesthetized male Sprague-Dawley rats were randomized to: (1) global myocardial ischemia/reperfusion, in which 8 min of ventricular fibrillation was induced and successful defibrillation was achieved after 6 min of cardiopulmonary resuscitation (CPR); (2) global myocardial ischemia, in which ventricular fibrillation and CPR were performed without defibrillation attempt; and (3) sham control.

Results

Myocardial function was significantly impaired after resuscitation. Mitochondria were massively swollen in global ischemic hearts and mildly swollen in the resuscitated hearts. Concomitantly, ATP levels abruptly declined during global ischemia and partially recovered after resuscitation. Furthermore, mitochondrial abnormalities were supported by the incapability of utilizing energy substrates manifested by the accumulations of intramyocellular lipid droplets and glycogen deposits.

Conclusions

In this model of cardiac arrest and CPR, the presence of ultrastructural mitochondrial abnormalities, further evidenced by the incapability of utilizing energy substrates and impairment of energy-production, might, in part, contribute to the development of postresuscitation myocardial dysfunction.     

乌司他丁对失血性休克大鼠回肠黏膜细胞凋亡的影响

目的 探讨乌司他丁对失血性休克大鼠回肠黏膜细胞凋亡的影响。方法 采用前瞻对照动物研究，用改良Chaudry方法制备大鼠失血性休克模型，60min后回输血液和生理盐水进行复苏，部分加用乌司他丁治疗。检测不同时间点血清肿瘤坏死因子-α（TNF-α）、丙二醛（MDA）含量和回肠黏膜细胞Bax、Bcl-2、caspase3蛋白的表达水平。结果 大鼠失血性休克及复苏后血清TNF-α、MDA含量以及回肠黏膜细胞Bax、caspase3蛋白的表达较正常对照组均明显升高，Bcl-2明显降低。复苏后血清TNF-α含量下降，MDA含量升高；回肠黏膜细胞Bax、caspase3蛋白的表达均明显下降，Bcl-2蛋白明显升高；乌司他丁复苏组上述指标的恢复程度较生理盐水复苏组为好。结论 乌司他丁可抑制失血性休克大鼠回肠黏膜细胞的凋亡，对失血性休克大鼠起保护作用。     

Anaesthetic Postconditioning at the Initiation of CPR Improves Myocardial and Mitochondrial Function in a Pig Model of Prolonged Untreated Ventricular Fibrillation

Background

Anaesthetic postconditioning (APoC) attenuates myocardial injury following coronary ischaemia/reperfusion. We hypothesised that APoC at the initiation of cardiopulmonary resuscitation (CPR) will improve post resuscitation myocardial function along with improved mitochondrial function in a pig model of prolonged untreated ventricular fibrillation.

Methods

In 32 pigs isoflurane anaesthesia was discontinued prior to induction of ventricular fibrillation that was left untreated for 15 min. At the initiation of CPR, 15 animals were randomised to controls (CON), and 17 to APoC with 2 vol% sevoflurane during the first 3 min CPR. Pigs were defibrillated after 4 min of CPR. After return of spontaneous circulation (ROSC), isoflurane was restarted at 0.8–1.5 vol% in both groups. Systolic and diastolic blood pressures were measured continuously. Of the animals that achieved ROSC, eight CON and eight APoC animals were randomised to have their left ventricular ejection fraction (LVEF%) assessed by echocardiography at 4 h. Seven CON and nine APoC were randomised to euthanasia 15 min after ROSC to isolate mitochondria from the left ventricle for bioenergetic studies.

Results

ROSC was achieved in 10/15 CON and 15/17 APoC animals. APoC improved haemodynamics during CPR and post-CPR LVEF%. Mitochondrial ATP synthesis, coupling of oxidative phosphorylation and calcium retention capacity were improved in cardiac mitochondria isolated after APoC.

Conclusions

In a porcine model of prolonged untreated cardiac arrest, APoC with inhaled sevoflurane at the initiation of CPR, is associated with preserved mitochondrial function and improved post resuscitation myocardial dysfunction.Approved by the Institutional Animal Care Committee of the Minneapolis Medical Research Foundation of Hennepin County Medical Center (protocol number 11-05).