Cardioprotective effect of nicorandil against myocardial injury following cardiac arrest in swine.

INTRODUCTION: Nicorandil, a vasodilatory drug used to treat angina, was reported to protect against myocardial ischemia-reperfusion injury in various animal models. However, its cardioprotective action following cardiac arrest is unknown. We examined the cardioprotective effects of nicorandil in a porcine model of cardiac arrest and resuscitation. METHODS: Ventricular fibrillation was induced electrically for 4min in anesthetized domestic swine, followed by cardiopulmonary resuscitation. Sixteen successfully resuscitated animals were randomized to saline control (n=8) or nicorandil (n=8) groups. Nicorandil (150µg/kg) was administered by central intravenous injection at onset of restoration of spontaneous circulation (ROSC), followed by 3µg/kg/min infusion until reperfusion end. Sham-operated animals received surgery only (n=4). Hemodynamic parameters were monitored continuously. Blood samples were taken at baseline, 5, 30, 180, and 360min after ROSC. Left ventricular ejection fraction was assessed by echocardiography at baseline and 6h after ROSC. The animals were euthanized 6h after ROSC, and the cardiac tissue was removed for analysis. RESULTS: 6 h after ROSC, nicorandil had significantly improved all hemodynamic variables (all P<0.05) except the maximum rate of left ventricular pressure decline and heart rate (P>0.05) compared with the control group. Control animals showed elevated cardiac troponin I and lactate levels compared with sham animals, which were significantly decreased following nicorandil treatment (P<0.05). In the saline control group, the adenosine triphosphate (ATP) content was largely reduced but subsequently rescued by nicorandil (P<0.05). Histopathologic injury was reduced with nicorandil treatment. Nicorandil reduced cardiomyocyte apoptosis as evidenced by reduced terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL)-positive cells, decreased Bax and caspase-3 expression, and increased Bcl-2 expression in the myocardium (all P<0.05). CONCLUSION: Nicorandil exhibited cardioprotective effects on myocardial injury following cardiac arrest via improvement in post-resuscitation myocardial dysfunction and energy metabolism, reduction in myocardial histopathologic injury, and antiapoptotic effects.

Sodium Ferulate Protects against Angiotensin II-Induced Cardiac Hypertrophy in Mice by Regulating the MAPK/ERK and JNK Pathways.

Background and Objective. It has been reported that sodium ferulate (SF) has hematopoietic function against anemia and immune regulation, inflammatory reaction inhibition, inhibition of tumor cell proliferation, cardiovascular and cerebrovascular protection, and other functions. Thus, this study aimed to investigate the effects of SF on angiotensin II- (AngII-) induced cardiac hypertrophy in mice through the MAPK/ERK and JNK signaling pathways. Methods. Seventy-two male C57BL/6J mice were selected and divided into 6 groups: control group, PBS group, model group (AngII), model + low-dose SF group (AngII + 10 mg/kg SF), model + high-dose SF group (AngII + 40 mg/kg SF), and model + high-dose SF + agonist group (AngII + 40 mg/kg SCU + 10 mg/kg TBHQ). After 7 d/14 d/28 days of treatments, the changes of blood pressure and heart rates of mice were compared. The morphology of myocardial tissue and the apoptosis rate of myocardial cells were observed. The mRNA and protein expressions of atrial natriuretic peptide (ANP), transforming growth factor-ß (TGF-ß), collagen III (Col III), and MAPK/ERK and JNK pathway-related proteins were detected after 28 days of treatments. Results. SF improved the mice's cardiac abnormality and decreased the apoptosis rate of myocardial cells in a time- and dose-dependent manner (all P < 0.05). MAPK/ERK pathway activator inhibited the protective effect of SF in myocardial tissue of mice (P < 0.05). SF could inhibit the expression of p-ERK, p-p38MAPK, and p-JNK and regulate the expressions of ANP, TGF-ß, and Col III (all P < 0.05). Conclusion. Our findings provide evidence that SF could protect against AngII-induced cardiac hypertrophy in mice by downregulating the MAPK/ERK and JNK pathways.

Complete mitochondrial genome sequence of the heart failure model of cardiomyopathic Syrian hamster (Mesocricetus auratus).

In this study we sequenced the complete mitochondrial genome sequencing of a heart failure model of cardiomyopathic Syrian hamster (Mesocricetus auratus) for the first time. The total length of the mitogenome was 16,267 bp. It harbored 13 protein-coding genes, 2 ribosomal RNA genes, 22 transfer RNA genes and 1 non-coding control region.

Shen-Fu injection reduces impaired myocardial ß-adrenergic receptor signaling after cardiopulmonary resuscitation.

BACKGROUND: Post-resuscitation myocardial dysfunction has been implicated as a major cause of fatal outcome in patients who survive initially successful cardiopulmonary resuscitation (CPR). In our previous study, we found that impaired myocardial ß-adrenergic receptor (AR) signaling is a key mechanism in post-resuscitation myocardial dysfunction and Shen-Fu injection (SFI) can attenuate post-resuscitation myocardial dysfunction. However, whether SFI can prevent impaired post-resuscitation myocardial ß-AR signaling is not yet known. In this study, we investigated the effect of SFI on impaired myocardial ß-AR signaling occurring post-resuscitation in a porcine model of cardiac arrest. METHODS: Ventricular fibrillation was induced electrically in anesthetized male landrace domestic pigs. After 4 minutes of untreated ventricular fibrillation, cardiopulmonary resuscitation was initiated. Sixteen successfully resuscitated pigs were randomized to receive a continuous infusion of either SFI (0.5 ml/min; n = 8) or saline (placebo; n = 8) for 6 hours, beginning 15 minutes after the return of spontaneous circulation (ROSC). Hemodynamic and echocardiographic data were recorded. ß-AR signaling was assessed at 6 hours after the intervention by measuring myocardial adenylate cyclase activity, ß-AR density and ß-AR kinase expression. RESULTS: Treatment with SFI produced better maximum rate of left ventricular pressure increase (dp/dt(max)) and maximum rate of left ventricular pressure decline (-dp/dt(max)), cardiac output, and ejection fraction after ROSC. SFI treatment was also associated with lower myocardial ß-adrenergic receptor kinase expression, whereas basal and isoproterenol-stimulated adenylate cyclase activity and the total ß-AR density were significantly increased in the SFI group when compared with the placebo group. CONCLUSION: SFI attenuated post-resuscitation myocardial dysfunction by preventing impaired myocardial ß-AR signaling after CPR.

Evaluation of respiratory dysfunction in a pig model of severe acute dichlorvos poisoning.

BACKGROUND: Respiratory failure is the main cause of death in acute organophosphorus pesticide poisoning. In this study, a pulse-induced contour cardiac output monitor was used to evaluate the respiratory status in a pig model of acute dichlorvos poisoning. METHODS: Twenty female pigs were randomly allocated to dichlorvos (n = 7), atropine (n = 7), and control (n = 6) groups. In the dichlorvos group, pigs were administered 80% emulsifiable dichlorvos (100 mg/kg) via a gastric tube. In the atropine group, pigs were similarly administered dichlorvos, and 0.5 hours later, atropine was injected to attain and maintain atropinization. The control group was administered saline solution. Arterial blood gas was measured at 0, 0.5, 1, 2, 4, and 6 hours post-injection. The extravascular lung water index and pulmonary vascular permeability index were recorded by the pulse-induced contour cardiac output monitor. At termination of the study, the animals were euthanized, the lung wet-to-dry weight ratio was determined, and histopathology was observed. RESULTS: In the dichlorvos group, the extravascular lung water index and pulmonary vascular permeability index were substantially increased from 0.5 hours and were particularly high within 1 hour. In the atropine group, these indices increased initially, but decreased from the 1-hour mark. The control group exhibited no obvious changes. In both the dichlorvos and atropine groups, the extravascular lung water index was negatively correlated with partial pressure of oxygen/fraction of inspiration oxygen (PO2/FiO2) and positively correlated with the pulmonary vascular permeability index. Compared with the control group, the lung wet-to-dry weight ratio markedly increased and the histopathological findings obviously changed in the dichlorvos group, but only mildly increased and changed, respectively, in the atropine group. CONCLUSION: The extravascular lung water index is an appropriate and valuable parameter for assessment of respiratory function in acute dichlorvos poisoning.

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

OBJECTIVE: To investigate the effects of Shen-Fu injection (SFI) on postresuscitation lung injury in a porcine model of cardiac arrest. METHODS: Twenty-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 6h after ROSC. RESULTS: Oxygenation 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, 1h, 2h, 4h, and 6h 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. CONCLUSION: Shen-Fu injection can attenuate postresuscitation lung injury through suppression of lung cell apoptosis and improvement of energy metabolism and antioxidant capacity.

Impaired ß-adrenergic receptor signalling in post-resuscitation myocardial dysfunction.

OBJECTIVE: Post-resuscitation myocardial dysfunction is a major cause of fatality in patients receiving successful cardiopulmonary resuscitation. The mechanism of post-resuscitation myocardial dysfunction is largely unknown, although is generally considered related to ischaemia occurring during cardiac arrest and resuscitation and/or reperfusion injury after restoration of circulation. A key mechanism responsible for reduced contractile reserves in chronic heart failure is impaired ß-adrenergic receptor signalling. Thus, we hypothesised that ß-adrenergic receptor signalling is markedly abnormal in the post-resuscitation period following cardiopulmonary resuscitation. METHODS: Male landrace domestic pigs were randomised into a sham group (anaesthetised and instrumented, no ventricular fibrillation) or cardiopulmonary resuscitation (CPR) group (ventricular fibrillation) (n=8 per group). Haemodynamic and echocardiographic data were recorded. ß-Adrenergic receptor signalling was assessed at 6h after the operation by measuring myocardial adenylate cyclase activity, ß-adrenergic receptor density and ß-adrenergic receptor kinase expression. RESULTS: Left ventricular function in the CPR group was significantly decreased at 6 h after restoration of spontaneous circulation. Basal and isoproterenol-stimulated adenylate cyclase activity was blunted in the CPR group compared with the sham group. Total ß-AR density was significantly decreased in CPR group compared with the sham group. Myocardial ß-adrenergic receptor kinase expression was 2.03-fold greater in the CPR group than in the sham group. CONCLUSIONS: ß-Adrenergic receptor signalling is markedly impaired in the post-resuscitation period, which may be a mechanism of post-resuscitation myocardial dysfunction.

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.

Comparison of the efficacy of nifekalant and amiodarone in a porcine model of cardiac arrest.

OBJECTIVE: To compare the efficacy of nifekalant and amiodarone in the treatment of cardiac arrest in a porcine model. METHODS: After 4min of untreated ventricular fibrillation, animals were randomly treated with nifekalant (2mgkg(-1)), amiodarone (5mgkg(-1)) or saline placebo (n=12 pigs per group). Precordial compression and ventilation were initiated after drug administration and defibrillation was attempted 2min later. Hemodynamics were continuously measured for 6h after successful resuscitation. RESULTS: Compared with saline, nifekalant and amiodarone equally decreased the number of electric shocks, defibrillation energy, epinephrine dose, and duration of cardiopulmonary resuscitation required for successful resuscitation (P<0.01). The incidence of restoration of spontaneous circulation (ROSC) and the 24-h survival rate were higher in both antiarrhythmic drug groups (P<0.05) vs. the saline group. Furthermore, post-resuscitation myocardial dysfunction at 4-6h after successful resuscitation was improved in animals given antiarrhythmic drugs as compared with the saline group (P<0.05). There were no differences between nifekalant and amiodarone for any of these parameters. CONCLUSION: The effect of nifekalant was similar to that of amiodarone for improving defibrillation efficacy and for the treatment of cardiac arrest. Administration of either nifekalant or amiodarone before defibrillation increased the ROSC and 24-h survival rates and improved post-resuscitation cardiac function in this porcine model.