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Objective:To evaluate the effects of different densities of rat cardiac fibroblasts (RCF) subjected to hypothermic hypoxia-reoxygenation on cardiomyocyte injury and intercellular coupling.Methods:RCF was cultured in vitro and divided into 3 groups ( n=12 each) using a random number table method: RCF density 0.5×10 5 cells/ml group (T 0.5 group), RCF density 1.0×10 5 cells/ml group (T 1.0 group), and RCF density 2.0×10 5 cells/ml group (T 2.0 group). The three groups were placed in an anoxic device, into which 95% N 2 + 5% CO 2 was continuously blown at the speed of 5 L/min for 15 min, and then placed in a 4 ℃ refrigerator for 1 h for low temperature treatment.After completion of culture, cells were placed in a incubator containing 95% air + 5% CO 2 at 37 ℃ for 4 h of reoxygenation.After the end of culture, RCF in three groups were indirectly co-cultured with cardiomyocytes of the same density (1.0×10 5 cells/ml) in a Transwell chamber for 16 h, cardiomyocytes were seeded in the lower chamber of Transwell, and RCF were seeded in the upper chamber of Transwell.After the end of co-culture, cardiomyocytes were collected for determination of the cell viability (by CCK8 method), apoptosis rate (by flow cytometry), expression of connexin 43 (Cx43) mRNA (by real-time fluorescence quantitative polymerase chain reaction), and expression of Cx43 and phosphorylated Cx43 (p-Cx43) (by Western blot). Results:Compared with T 0.5 group, the cell viability, apoptosis rate and expression of Cx43, p-Cx43 and Cx43 mRNA were significantly decreased in T 1.0 and T 2.0 groups ( P<0.01). Compared with T 1.0 group, the cell viability, apoptosis rate and expression of Cx43 and p-Cx43 were significantly decreased ( P<0.01), and no significant change was found in expression of Cx43 mRNA in cardiomyocytes in T 2.0 group ( P>0.05). Conclusions:RCF subjected to hypothermic hypoxia-reoxygenation induces cardiomyocyte injury in a density-dependent manner in a certain range, and the mechanism may be related to down-regulation of the expression of Cx43 and reduction of the activity of Cx43.
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Objective:To investigate the effect of diabetes mellitus on pulmonary uptake of sevoflurane.Methods:Twenty patients with type 2 diabetes mellitus, aged 40-64 yr, with body mass index of 18.5-22.9 kg/m 2, of American Society of Anesthesiologists physical status Ⅰ or Ⅱ, undergoing elective surgery with general anesthesia, served as diabetes group (group D). Twenty non-diabetic patients matched by age, gender and surgery were selected as control group (group C). After anesthesia induction and tracheal intubation, sevoflurane was inhaled at a concentration of 2% (oxygen flow 2 L/min). The inhaled concentration (Fi) and exhaled concentration (Fa) at 1, 3, 5, 10, 15, 20 and 30 min of inhalation of sevoflurane were recorded, and the Fa/Fi ratio was calculated.The time required for the Fa/Fi ratio to reach 0.7 was recorded. Results:Compared with group C, the Fa/Fi ratio was significantly increased at each time point, and the time required for the Fa/Fi ratio to reach 0.7 was shortened in group D ( P<0.05). Conclusion:Diabetes mellitus can reduce pulmonary uptake of sevoflurane in the patients.
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Objective:To evaluate the effects of different density rat fibroblasts on the expression of conjunctin 43 (Cx43) in cardiomyocytes and cell viability.Methods:Cardiomyocytes and fibroblasts were co-cultured using Transwell, cardiomyocytes were inoculated into the lower chamber of Transwell and fibroblasts into the upper chamber of Transwell.The cells were divided into 3 groups ( n=12 each) by a random number table method: fibroblast density 0.5×10 5 cells/ml group (group C 0.5), fibroblast density 1×10 5 cells/ml group (group C 1), and fibroblast density 2×10 5 cells/ml group (group C 2), with the density of cardiomyocytes 1×10 5 cells/ml in three groups.Cardiomyocytes and fibroblasts were co-cultured for 20 h in three groups.Cardiomyocytes were collected after co-culture for determination of cell viability (by CCK8 method), apoptosis rate (by flow cytometry), and expression of Cx43 mRNA (by quantitative real-time polymerase chain reaction) and expression of Cx43 and phosphorylated Cx43 (p-Cx43) (by Western blot). Results:There was no significant difference in the apoptosis rate of cardiomyocytes among the three groups ( P>0.05). Compared with group C 0.5, the expression of Cx43 protein and mRNA and p-Cx43 was significantly up-regulated in group C 1, the cardiomyocyte viability was significantly increased, and the expression of Cx43 protein and mRNA and p-Cx43 was up-regulated in group C 2 ( P<0.05). Compared with group C 1, the cardiomyocyte viability was significantly increased, and the expression of Cx43 protein and mRNA and p-Cx43 was up-regulated in group C 2 ( P<0.05). Conclusion:Rat fibroblasts up-regulate the expression of Cx43 and enhance the activity of Cx43 in cardiomyocytes and enhance cell viability in a density-dependent manner in a certain range.
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Objective:To summarize the strategy of using extracorporeal membrane oxygenation (ECMO) support during lung transplantation from 2 coronavirus disease 2019 (COVID-19) with end-stage respiratory failure.Methods:Two COVID-19 with end-stage respiratory failure patients were admitted to Nanjing Medical University Affiliated Wuxi People's Hospital in March 2020. As the homoeostasis and vital signs could not be maintained in balance by conventional treatments, lung transplantations were performed. Here, detail information about combined application of peripheral veno-venous ECMO (VV-ECMO) and central veno-arterial ECMO (CVA-ECMO) during the operation will be discussed.Results:Case 1: 59 years old, 172 cm height, 72 kg weight, who received mechanical ventilation for 22 days, tracheotomy tube for 17 days, and VV-ECMO support for 7 days. Case 2: 72 years old, 178 cm height, 71 kg weight, who received mechanical ventilation for 19 days, tracheotomy tube for 17 days, and VV-ECMO support for 18 days. As both of them have severe COVID-19-associated respiratory failure, and the recovery was determined to be unlikely, lung transplantations were performed. Severe pulmonary arterial hypertension (PAH) and cardiac insufficiency were found during the operation. Based on preoperative VV-ECMO, CVA-ECMO was added. The concomitant use of peripheral VV-ECMO and CVA-ECMO offered satisfied intraoperative oxygenation and cardiopulmonary status, the operations run smoothly, and the CVA-ECMO was successfully removed, no ECMO-related complications occurred.Conclusion:The combined use of VV-ECMO and CVA-ECMO is an optimal strategy in the end-stage ARDS patients with severe PAH and cardiac insufficiency, which can offer benefits on respiratory and cardiac functions simultaneously, and ensure surgery safety.
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Objective:To explore the safety and nosocomial infection control measures of COVID-19 patients of end-stage respiratory failure after lung transplantation.Methods:Lung transplantation was performed for a COVID-19 patient with end-stage respiratory failure after a negative conversion of 2019-nCoV nucleic acid. Before operation, all medical staff received simulated training on nosocomial infection. The procedures were performed in an operation room with a negative pressure environment. The three-grade preventive strategy was implemented and wearing positive pressure protective mask of electric air supply required. During operation, the patient was managed according to the in-hospital protection process. The environment and medical instruments were disinfected after operation.Results:The operation was completed successfully. The 2019-nCoV nucleic acid test was negative for many times after operation. Participants were placed in medical isolation for 14 days after surgery. During the period, nucleic acid test was negative twice.Conclusions:As an exploratory treatment, lung transplantation is a safe option for end-stage respiratory failure in COVID-19 in operation room with a negative pressure environment and implementations of three-grade preventive strategy.
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Objective:To determine the changes in the expression of myocardial miRNA and the target genes in the rats with hypothermic ischemia-reperfusion (I/R) arrhythmia.Methods:Clean-grade healthy male Sprague-Dawley rats, aged 2-3 months, weighing 300-400 g, were anesthetized, the chest was opened, and the heart was taken to establish an isolated heart perfusion model.Six successfully perfused isolated hearts were divided into 2 groups ( n=3 each) using a random number table method: control group (group C) and heart I/R group (IR group). The model of hypothermic global I/R injury was established by interrupting perfusion for 60-min followed by 30-min reperfusion in chloral hydrate-anesthetized rats.The arrhythmia score was recorded during reperfusion.High-throughput sequencing was used to identify the differentially expressed miRNAs in two groups.The RNAhybrid and miRanda databases were used to predict the target genes of mRNA regulated by the differentially expressed miRNAs, and the enrichment for target genes was performed by Gene Ontology and KEGG databases, and the miRNAs closely related to arrhythmia and with higher expression were selected to carry out the real-time polymerase chain reaction detection. Results:The results of high-throughput sequencing showed that there were 7 differentially expressed miRNAs (novel-miR-17, novel-miR-19, novel-miR-30, novel-miR-43, rno-miR-122-5p, novel-miR-16 and rno-miR-429) in group IR as compared with group C. There were 4 miRNAs that were closely related to arrhythmia and had higher expression: the expression of novel-miR-17, novel-miR-30 and rno-miR-122-5p was significantly up-regulated, and the expression of rno-miR-429 was down-regulated in group IR when compared with group C ( P<0.05). The miRNA-mRNA correlation analysis revealed that GJA1 gene was the target of novel-miR-17. Conclusion:Myocardial novel-miR-17 is involved in the occurrence of hypothermic I/R arrhythmia probably by acting on GJA1 gene in rats.
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Objective:To evaluate the changes in the electrical conduction of ventricular myocardium during hypothermic ischemia-reperfusion (I/R) in rats with arrhythmia.Methods:Healthy clean-grade adult male Sprague-Dawley rats, aged 2-3 months, weighing 200-300 g, were studied.The hearts were removed and retrogradely perfused with oxygenated K-H solution in a Langendorff apparatus. Sixteen isolated hearts were divided into 2 groups ( n=8 each) using a random number table method: normal control group (group C) and hypothermic I/R group (group I/R). In group C, the heart was perfused with K-H solution at 37 ℃ for 120 min.In group I/R, the heart was perfused with K-H solution at 37 ℃ for 30 min, and then perfusion was stopped, cardiac arrest was induced through injecting Thomas solution (4 ℃), the area around the heart was protected with low temperature (4 ℃) Thomas solution, and hearts were perfused with 4 ℃ Thomas solution at 30 min after cardiac arrest and with 37 ℃ K-H solution for 30 min staring from 60 min after cardiac arrest.The rats in group I/R were further divided into high-risk subgroup (I/R-H subgroup) and low-risk subgroup (I/R-L subgroup). The time of spontaneous recovery of heart beat and development of arrhythmia were recorded.At the end of reperfusion, the atrioventricular conduction 2∶1 block point (2∶1B) and ventricular electrical conduction velocity (CV) were measured and recorded by program-controlled electrical stimulation. Results:Compared with group C, CV and 2∶1B were significantly decreased in IR-L and IR-H subgroups ( P<0.05). Compared with IR-L subgroup, the time for restoration of spontaneous heart beat was significantly prolonged, the incidence of ventricular fibrillation and arrhythmia score were increased, and CV and 2∶1B were decreased in IR-H subgroup ( P<0.05). Conclusion:The electrical CV of ventricular myocardium is decreased during hypothermic I/R, which may be the mechanism of reperfusion-induced ventricular arrhythmia in rats with arrhythmia.
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Objective:To evaluate the effect of electroacupuncture (EA) on electrophysiological characteristics of ventricular myocardium during myocardial ischemia-reperfusion (I/R) in rats.Methods:Twenty-four clean-grade healthy adult male Sprague-Dawley rats, weighing 280-320 g, were divided into 3 groups ( n=8 each) using a random number table method: sham operation group (group SH), I/R group and group EA.The model of myocardial I/R injury was established by ligating the left anterior descending branch of coronary artery for 30 min followed by 30-min reperfusion in anesthetized rats.Bilateral Neiguan acupoints in forelimbs were stimulated for 30 min during the period of reperfusion in group EA.Heart rate (HR), monophasic action potential amplitude (MAPA), maximum depolarization rate (V max), and monophasic action potential duration at 90% repolarization (MAPD 90) were recorded.The development of arrhythmias and arrhythmias score were recorded during reperfusion. Results:Compared with group SH, HR was significantly decreased, MAPA and V max were decreased, MAPD 90 was prolonged, and the incidence of ventricular premature beat, ventricular tachycardia and ventricular fibrillation and arrhythmias score were increased at T 1, 2 in I/R and EA groups ( P<0.05). Compared with group I/R, HR was significantly increased, MAPA and V max were increased, MAPD 90 was shortened, and the incidence of ventricular tachycardia and ventricular fibrillation and arrhythmias score were decreased at T 2 in EA group ( P<0.05). Conclusion:EA can accelerate myocardial depolarization and shorten repolarization, thus decreasing the occurrence of reperfusion arrhythmia in rats.
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Objective:To evaluate the relationship between decreased atrial myoelectric conduction and gap junction protein 40 (Cx40) and Cx43 in rats with reperfusion atrial arrhythmia.Methods:Sixteen Langendorff-isolated heart perfusion models were randomly divided into control group (group C) and ischemia-reperfusion group (group IR), with 8 rats in each group.According to whether the atrial arrhythmia occurred after reperfusion, group IR was further divided into reperfusion non-atrial arrhythmia subgroup (group R-NAA) and reperfusion atrial arrhythmia subgroup (group R-AA). Group C was balanced perfusion with K-H solution (37 ℃) for 120 min.In group IR, hearts were perfused with K-H solution (37 ℃) for 30 min, perfusion was then stopped, Thomas solution (4 ℃, 20 ml/kg) was injected to induce cardiac arrest for 60 min, the surrounding of the heart was protected with 4 ℃Thomas solution, and hearts were perfused with Thomas solution (4 ℃, 10 ml/kg) again after 30 min of cardiac arrest and then with K-H solution 37 ℃ for 30 min.At 120 min of equilibration or 30 min of reperfusion, the effective refractory period (ERP) and conduction velocity (CV) of the right atrium were measured, the expression of Cx40 and Cx43 in the right atrial myocardium was detected by Western blot, and ratio of Cx40 to Cx40+ Cx43 and the ratio of Cx43 to Cx40+ Cx43 were calculated.Results:The incidence of reperfusion atrial arrhythmia was 38% in group IR.Compared with group C, ERP was significantly prolonged, CV was decreased, the expression of Cx40 and Cx43 was down-regulated, the ratio of Cx40 to Cx40+ Cx43 was increased, and the ratio of Cx43 to Cx40+ Cx43 was decreased in R-NAA and R-AA groups ( P<0.05). Compared with group R-NAA, ERP was significantly prolonged, CV was decreased, the expression of Cx40 and Cx43 was down-regulated, the ratio of Cx40 to Cx40+ Cx43 was increased, and the ratio of Cx43 to Cx40+ Cx43 was decreased in group R-AA ( P<0.05). Conclusion:The decreased atrial myoelectric conduction may be related to the down-regulation of Cx40 and Cx43 expression in rats with reperfusion atrial arrhythmia.
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Objective:To observe the changes in the expression of microRNAs in ventricular myocardium in a rat model of hypothermic ischemia-reperfusion (I/R).Methods:Healthy clean-grade male Sprague-Dawley rats, aged 2-3 months, weighing 300-400 g, were anesthetized with intraperitoneal chloral hydrate.Their hearts were excised and perfused in a Langendorff apparatus with K-H solution saturated with 95%O 2-5%CO 2.Sixteen Langendorff-perfused hearts were prepared and divided into 2 groups ( n=8 each) by a random number table method: control group (group C) and hypothermic I/R group (group I/R). The hearts were made globally ischemic for 60 min followed by 30-min hypothermic (4 ℃) reperfusion to establish the model of hypothermic I/R injury.The type and duration of arrhythmia and time of recovery of spontaneous heartbeats were recorded during reperfusion.The rats in group I/R were further divided into low-risk group (I/R-L group) and high-risk group (I/R-H group). The left ventricular myocardium was collected after the end of perfusion for high throughput sequencing to screen the differentially expressed microRNAs, and the reliability of the sequencing results was verified by quantitative real-time polymerase chain reaction.Gene Ontology and KEGG databases were used to analyze the biological regulatory pathways of differentially expressed target genes. Results:Compared with group C, there were 437 up-regulated microRNAs and 242 down-regulated microRNAs in group I/R-L and 419 up-regulated microRNAs and 260 down-regulated microRNAs in group I/R-H.Compared with group I/R-L, 392 microRNAs were up-regulated, and 287 microRNAs were down-regulated in group I/R-H.There were 84 microRNAs with absolute value of fold change ≥2 and significantly differential expression ( P<0.01) among the three groups.Subsequently, 4 microRNAs were randomly selected for validation using quantitative real-time polymerase chain reaction, confirming that the sequencing results were reliable.These differentially expressed target genes were involved in 11 biological processes and 6 KEGG pathways which were related to reperfusion arrhythmia.Potassium ion transmembrane transport and the adrenergic receptor signaling pathway in cardiomyocytes were enriched by the largest number of target genes. Conclusion:The expression of microRNAs in ventricular myocardium changes significantly after heart hypothermic I/R.These differentially expressed microRNAs regulate potassium ion transmembrane transport probably and mainly through the adrenergic receptor signaling pathway in the cardiomyocytes and thus are involved in the occurrence and development of hypothermic I/R arrhythmias.
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Objective To evaluate the effect of sevoflurane on the electrophysiological stability of i-solated rat hearts subjected to hypothermic perfusion. Methods Clean-grade healthy adult male Sprague-Dawley rats, weighing 280-360 g, were heparinized and anesthetized with pentobarbital sodium. Their hearts were excised and perfused in a Langendorff apparatus with K-H solution saturated with 95％ O2-5％CO2 at 37℃. Twenty-four Langendorff-perfused hearts were divided into 4 groups ( n=6 each) using a ran-dom number table method: control group ( C group ) , sevoflurane group ( S group ) , 32 ℃ hypothermia group ( H group) and 32℃ hypothermia plus sevoflurane group ( HS group) . After 15 min of equilibration, the isolated hearts were continuously perfused for 30 min with K-H solution at 37℃, with K-H solution con-taining 2. 3％ sevoflurane at 37 ℃, with K-H solution at 32 ℃, and with K-H solution containing 2. 3％sevoflurane at 32℃ in C, S, H and HS groups, respectively. Heart rate and monophasic action potential in three layers of the left ventricular anterior wall were recorded at 15 min of equilibration ( T0 ) and 30 of con-tinuous perfusion ( T2 ) , the transmural dispersion of repolarization ( TDR) were calculated, and the occur-rence of arrhythmia was observed. Results Compared with C and S groups, the heart rate was significantly decreased and TDR was enlarged at T1 , and the incidence of arrhythmia was increased in H and HS groups ( P<0. 05) . Compared with H group, TDR was significantly reduced at T1 , and the incidence of arrhythmia was decreased in HS group ( P<0. 05) . Conclusion Sevoflurane can improve the electrophysiological in-stability of isolated rat hearts subjected to hypothermic perfusion, and thus decrease the development of ar-rhythmia.
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Objective To evaluate the electrophysiological changes of atrial myocardium in a rat model of hypothermic ischemia-reperfusion (I/R).Methods Sixteen isolated Sprague-Dawley rat hearts successfully perfused in the Langendorff apparatus were divided into control group (group C) and hypothermic I/R group (group IR) using a random number table method,with 8 heats in each group.Heats in group IR were further divided into reperfusion-non-atrial arrhythmia subgroup (group R-NAA) and reperfusion-atrial arrhythmia subgroup (group R-AA) depending on whether atrial arrhythmia occurred after reperfusion.In group C,the heart was perfused with K-H solution at 37 ℃ for 120 min.In group IR,the heart was perfused with K-H solution at 37 ℃ for 30 min and then perfusion was stopped,cardiac arrest was induced for 60 min through injecting Thomas solution (4 ℃,20 ml/kg),the area around the heart was protected with low temperature (4 ℃℃) Thomas solution,and hearts were resuscitated with 4 ℃ Thomas solution (10 ml/kg) at 30 min after cardiac arrest and with 37 ℃ K-H solution for 30 min staring from 60 min after cardiac arrest.At 30 min of equilibration (T0),105 min of equilibration/15 min of reperfusion (T1),and 120 min of equilibration/30 min of reperfusion (T2),right atrial monophasic action potentials,maximal velocity of phase zero,monophasic action potential amplitude (MAPA) and MAP duration at 50％ and 90％ of repolarization (MAPDs0and MAPDg0) were measured.Right-atrium conduction velocity and effective refractory period were recorded at T2,and the ratio of ERP to MAPD90 (ERP/MAPD90) was calculated.Atrial fibrillation was induced by programmed electrical stimulation,and the maximum pacing cycle length of inducing atrial fibrillation (AF-PCLm=) was recorded.Results Compared with C and R-NAA groups,the maximal velocity of phase zero was significantly decreased and MAPDg0 was increased at T1,the right-atrium conduction velocity and ERP/MAPDg0 ratio were decreased and MAPD90,effective refractory period and AF-PCLmax were increased at T2 in group R-AA (P＜ 0.05).Conclusion The decrease in depolarization velocity,prolongation of repolarization duration and decrease in conduction velocity,excitability and electrical stability may be the electrophysiological mechanism of reperfused atrial arrhythmia in rats.
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Objective To evaluate the effect of sevoflurane on phosphorylation of connexin 43 (Cx43) at Ser368 (Cx43 Ser368) in ventricular myocardium in isolated hearts of diabetic rats.Methods Twenty-four clean-grade healthy adult male Sprague-Dawley rats,aged 3 months,weighing 180-220 g,were used in this study.The diabetic model was established by intraperitoneally injecting streptozotocin 60 mg/kg.The hearts were rapidly excised and retrogradely perfused with K-H solution saturated with 95％ O2-5％ CO2 at 37 ℃ in a Langendorff apparatus.Sixteen Langendorff-perfused diabetic hearts were divided into 3 groups (n =8 each) using a random number table method:diabetes mellitus group (group D) and sevoflurane group (group DS).Another 8 Langendorff-perfused normal hearts of rats were selected and served as control group (group C).After 15 min equilibration with K-H solution,the hearts were continuously perfused for 30 min with K-H solution in group C and group D and with K-H solution saturated with 2.5％ sevoflurane in group DS.S1S2 program-controlled stimulation was performed at the end of perfusion,the occurrence of induced ventricular arrhythmia (VA) and the maximal pacing cycle length (PCL) of induced VA were recorded,and conduction velocity (CV) was calculated.The expression of phosphorylated Cx43 at Ser368 (p-Cx43 Ser368) in ventricular myocytes was determined by Western blot.Results Compared with group C,the incidence of induced VA was significantly increased,the maximal PCL of induced VA was prolonged,the CV was decreased,and the expression of p-Cx43 Ser368 was up-regulated in group D (P＜0.05).Compared with the incidence of induced VA was significantly decreased,the maximal PCL of induced VA was shortened,the CV was increased,and the expression of p-Cx43 Ser368 was down-regulated in group DS (P＜0.05).Conclusion The mechanism by which sevoflurane stabilizes the ventricular electrical conduction is associated with decreasing the phosphorylation of Cx43 at Ser368 in diabetic rats.
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Objective@#To evaluate the electrophysiological changes of atrial myocardium in a rat model of hypothermic ischemia-reperfusion (I/R).@*Methods@#Sixteen isolated Sprague-Dawley rat hearts successfully perfused in the Langendorff apparatus were divided into control group (group C) and hypothermic I/R group (group IR) using a random number table method, with 8 heats in each group.Heats in group IR were further divided into reperfusion-non-atrial arrhythmia subgroup (group R-NAA) and reperfusion-atrial arrhythmia subgroup (group R-AA) depending on whether atrial arrhythmia occurred after reperfusion.In group C, the heart was perfused with K-H solution at 37 ℃ for 120 min.In group IR, the heart was perfused with K-H solution at 37 ℃ for 30 min and then perfusion was stopped, cardiac arrest was induced for 60 min through injecting Thomas solution (4 ℃, 20 ml/kg), the area around the heart was protected with low temperature (4 ℃) Thomas solution, and hearts were resuscitated with 4 ℃ Thomas solution (10 ml/kg) at 30 min after cardiac arrest and with 37 ℃ K-H solution for 30 min staring from 60 min after cardiac arrest.At 30 min of equilibration (T0), 105 min of equilibration/15 min of reperfusion (T1), and 120 min of equilibration/30 min of reperfusion (T2), right atrial monophasic action potentials, maximal velocity of phase zero, monophasic action potential amplitude (MAPA) and MAP duration at 50% and 90% of repolarization (MAPD50 and MAPD90) were measured.Right-atrium conduction velocity and effective refractory period were recorded at T2, and the ratio of ERP to MAPD90 (ERP/MAPD90) was calculated.Atrial fibrillation was induced by programmed electrical stimulation, and the maximum pacing cycle length of inducing atrial fibrillation (AF-PCLmax) was recorded.@*Results@#Compared with C and R-NAA groups, the maximal velocity of phase zero was significantly decreased and MAPD90 was increased at T1, the right-atrium conduction velocity and ERP/MAPD90 ratio were decreased and MAPD90, effective refractory period and AF-PCLmax were increased at T2 in group R-AA (P<0.05).@*Conclusion@#The decrease in depolarization velocity, prolongation of repolarization duration and decrease in conduction velocity, excitability and electrical stability may be the electrophysiological mechanism of reperfused atrial arrhythmia in rats.
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Objective@#To evaluate the effect of sevoflurane on phosphorylation of connexin 43 (Cx43) at Ser368 (Cx43 Ser368) in ventricular myocardium in isolated hearts of diabetic rats.@*Methods@#Twenty-four clean-grade healthy adult male Sprague-Dawley rats, aged 3 months, weighing 180-220 g, were used in this study.The diabetic model was established by intraperitoneally injecting streptozotocin 60 mg/kg.The hearts were rapidly excised and retrogradely perfused with K-H solution saturated with 95% O2-5% CO2 at 37 ℃ in a Langendorff apparatus.Sixteen Langendorff-perfused diabetic hearts were divided into 3 groups (n=8 each) using a random number table method: diabetes mellitus group (group D) and sevoflurane group (group DS). Another 8 Langendorff-perfused normal hearts of rats were selected and served as control group (group C). After 15 min equilibration with K-H solution, the hearts were continuously perfused for 30 min with K-H solution in group C and group D and with K-H solution saturated with 2.5% sevoflurane in group DS.S1S2 program-controlled stimulation was performed at the end of perfusion, the occurrence of induced ventricular arrhythmia (VA) and the maximal pacing cycle length (PCL) of induced VA were recorded, and conduction velocity (CV) was calculated.The expression of phosphorylated Cx43 at Ser368 (p-Cx43 Ser368) in ventricular myocytes was determined by Western blot.@*Results@#Compared with group C, the incidence of induced VA was significantly increased, the maximal PCL of induced VA was prolonged, the CV was decreased, and the expression of p-Cx43 Ser368 was up-regulated in group D (P<0.05). Compared with the incidence of induced VA was significantly decreased, the maximal PCL of induced VA was shortened, the CV was increased, and the expression of p-Cx43 Ser368 was down-regulated in group DS (P<0.05).@*Conclusion@#The mechanism by which sevoflurane stabilizes the ventricular electrical conduction is associated with decreasing the phosphorylation of Cx43 at Ser368 in diabetic rats.
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Objective To investigate the electrophysiological characteristics of myocardium after hypothermic ischemia-reperfusion (I/R) in rats with different degrees of arrhythmia using an in vitro experiment.Methods Healthy clean-grade male Sprague-Dawley rats,aged 2-3 months,weighing 300-400 g,were used in this study.The rats were sacrificed after anesthesia,and their hearts were rapidly excised.Sixteen Langendorff-perfused hearts were prepared and divided into 2 groups (n=8 each) by a random number table method:control group (group C) and hypothermic I/R group (group I/R).The hearts were made globally ischemic for 60 min followed by 30-min hypothermic (4 ℃) reperfusion to establish the model of hypothermic I/R injury.The occurrence and duration of arrhythmia and time of recovery of spontaneous heartbeat were recorded during reperfusion.The rats in group I/R were further divided into low-risk group (I/R-L group,ventricular arrhythmia score≤3 points) and high-risk group (I/R-H group,ventricular arrhythmia score＞3 points) according to the arrhythmia score.Monophasic action potential amplitude (MAPA),monophasic action potential (MAP) duration at 50％ and 90％ repolarization (MAPDs0 and MAPD90) and maximum ascending velocity (Vmax) of phase 0 in the endocardium,myocardium and epicardium of the left ventricular anterior wall were recorded at 30 min of equilibration (T0) and 15 and 30 min of reperfusion (T1,2).The effective refractory period (ERP) and ventricular fibrillation threshold (VFT) of the left ventricle were measured by programmed electrical stimulation,and the ERP/MAPD90 ratio was calculated.Results Compared with the baseline at T0,MAPA in the three layers was significantly decreased,and MAPD50 and MAPD90 were prolonged at T1,2 in I/R-L and I/R-H groups,and V in the three layers was decreased at T1,2 in I/R-H group (P＜0.05).MAPD50 and MAPD90 in the three layers were significantly shorter at T2 than at T1 in I/R-L and I/R-H groups (P＜0.05).Compared with group C,MAPDs0,MAPDg0 and ERP in the three layers were significantly prolonged at T1,2,the ERP/MAPDg0 ratio was decreased,and VFT was increased in I/R-L and I/R-H groups (P ＜ 0.05).Compared with I/R-L group,the duration of arrhythmia and MAPD90 and ERP in the three layers were significantly prolonged at T2,the ERP/MAPDg0 ratio was decreased,and VFT was increased in group I/R-H (P＜0.05).Conclusion Myocardial depolarization is inhibited,repolarization duration is prolonged,and electrophysiological stability is decreased after hypothermic I/R in the rats with arrhythmia,and the prolongation of myocardial repolarization and decrease in electrophysiological stability are more obvious in the rats at high risk of arrhythmia.
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Objective To evaluate the role of sarcolemmal ATP-sensitive potassium ( sarcKATP ) channel in sevoflurane-induced maintenance of electrophysiological stability of ventricular myocardium in di-abetic rats. Methods Clean-grade healthy male Sprague-Dawley rats, aged 3 months, weighing 280-320 g, in which diabetes mellitus ( DM) was induced by intraperitoneal streptozotocin 60 mg/kg and confirmed by blood glucose ≥16. 7 mmol/L, were used in this study. Their hearts were excised after anesthesia and retrogradely perfused in a Langendorff apparatus at 4 weeks after establishing the DM model. Twenty-four Langendorff-perfused hearts were divided into 3 groups ( n=8 each) using a random number table method:DM group ( group D) , DM plus sevoflurane group ( group DS) and DM plus sevoflurane plus HMR-1098 group (group DSH). Another 8 Langendorff-perfused hearts of normal rats were selected as control group ( group C) . Hearts were perfused with 37℃ K-H solution via the aorta in each group, 15 min of equilibra-tion later hearts were continuously perfused for 30 min with K-H solution in C and D groups, with K-H solu-tion saturated with 2. 5％ sevoflurane in group DS, or with K-H solution saturated with 10 μmol/L HMR-1098 and 2. 5％ sevoflurane in group DSH. Monophasic action potential (MAP) duration at 50％ and 90％repolarization ( MAPD50 and MAPD90 ) in the endocardium and epicardium of the left ventricular anterior wall were recorded at 15 min of equilibration ( T0 ) and 15 and 30 min of reperfusion ( T1,2 ) , transmural dispersion of repolarization ( TDR) was calculated. S1S2 program-controlled stimulation was performed at the end of perfusion to record the effective refractory period (ERP), ventricular arrhythmia (VA) induced and the longest pacing cycle length ( PCL) of ventricular fibrillation threshold ( VFT) induced. ERP/MAPD90 ratio was calculated. Results Compared with group C, TDR was significantly increased at T0 , ERP/MADP90 ratio was decreased, the incidence of VA induced was increased, and the longest PCL of VFT induced was prolonged in group D ( P＜0. 05) . Compared with group D, TDR was significantly decreased at T2 in group DS (P＜0. 05), and ERP/MADP90 ratio was significantly increased, the incidence of VA in-duced was decreased, and the longest PCL of VFT induced was shortened in DS and DSH groups ( P＜0. 05). TDR was significantly smaller at T2 in group DSH than in group DS (P＜0. 05). Conclusion sarcKATP channel is involved in sevoflurane-induced maintenance of electrophysiological stability of ventricu-lar myocardium in diabetic rats.
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Objective To study the effects of different concentrations of sevoflurane on monophasic action potentials (MAPs)of three-layer myocardium of ischemia reperfusion in isolated rat hearts.Methods Thirty-two healthy SD male rats,weighing 280-320 g,were randomly divided into four groups after successful preparation of langendorff isolated heart perfusion model and 1 5 min perfusion and balance of K-H fluid.In the ischemia-reperfusion group(group IR),K-H fluid perfusion was stopped and balanced for 15 min and cardiac arrest was induced for 60 min with the injection of Thomas solution (4℃,20 ml/kg)while the heart was protected by the low temperature Thomas so-lution (4℃)around it.Reperfusion of Thomas solution (4℃,10 ml/kg)was performed for 30 min and the heart was resuscitated by the perfusion of K-H fluid for 60 min.In the 0.5 MAC sevoflurane group (group Sev0.5 ),K-H fluid contained 0.5 MAC sevoflurane and other procedures were the same as in group IR.1.0 MAC sevoflurane group (group Sev1.0 ),K-H fluid contained 1.0 MAC sevoflurane and other procedures were the same as in group IR.2.0 MAC sevoflurane group (group Sev2.0),K-H fluid contained 2.0 MAC sevoflurane and other procedures were same as in group IR. HR,MAPs including time course (MAPD50,MAPD90)and MAP amplitude of endocardium,mid-layer myodardium and epicardium was recorded at the time of continuous balance perfusion for 1 5 min (T0),continuous perfusion for 15 min (T1),reperfusion for 15 min (T2)and 30 min (T3). Results Compared with T0and T1,HR was slower at T2and T3(P<0.05);Compared with group IR at T2and T3,HR in group Sev0.5 and group Sev1.0 was higher,that in group Sev2.0 was slower P<0.05);At T2,arrhythmia was observed in 6 rats in group IR,while arrhythmia was observed in 1 rats in group Sev0.5 ,and arrhythmia was observed in 2 rats in group Sev1.0 and arrhythmia was observed in 1 rats in group Sev2.0;Compared with group IR at T3,MAPD50in group Sev0.5 was shorter in three sites(P<0.05);Compared with group IR at T3,MAPD90in other three groups was shorter.Conclusion Different concentrations of sevoflurane can shorten MAPD90of MAPs,and the effects don＇t depend on the concertrations of sevoflurane when it changes from 0.5 MAC to 2.0 MAC;which may be the mechanism of decreased arrhythmias risk caused by sevoflurane.
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Objective To evaluate the effects of different analgesics combined with propofol of intravenous anesthesia on postoperative analgesia and emotion in patients of artificial abortion. Methods One hundred and twenty-two patients who had underwent painless artificial abortion were selected. The patients were divided into 4 groups by random digits table method: simple propofol group (C group, 29 cases), fentanyl combined with propofol group (F group, 30 cases), oxycodone combined with propofol group (Q group, 30 cases) and sufentanil combined with propofol group (S group, 33 cases). The induced dose of propofol was 2.5 mg/kg. When patients had limb movement during operation, a single addition of propofol 0.5 mg/kg was added until the body movement disappeared. The changes of mean arterial pressure (MAP), heart rate and respiratory rate before and after operation were compared among the 4 groups. The emotional status was assessed with affective scale before operation and 1 h after operation. The visual analog scale (VAS) was used to evaluate the degree of abdominal pain at 10, 30 and 60 min after palinesthesia. The propofol dose, operation time, recovery time and adverse reaction were recorded. Results No obvious adverse reactions were found during the operation. There was no statistical difference in operation time among 4 groups (P>0.05). The propofol dose, recovery time, body movement and the VAS score at 10, 30, 60 min after palinesthesia in F group, Q group and S group were significantly lower than those in C group, and there were statistical differences (P0.05). The MAP, heart rate and respiratory rate at beginning of the surgery and during the surgery were significantly lower than that before anesthesia in the 4 groups, and there were statistical differences (P0.05). The positive affective score after operation in C group, F group, Q group and S group was significantly higher than that before operation: (24.6 ± 5.6) scores vs. (21.7 ± 6.2) scores, (24.6 ± 3.1) scores vs. (20.6 ± 4.6) scores, (28.3 ± 6.3) scores vs. (20.8 ± 5.3) scores and (25.2 ± 5.4) scores vs. (19.9 ± 4.8) scores, and the negative affective score after operation in C group, F group, Q group and S group was significantly lower than that before operation: (17.0 ± 5.3) scores vs. (29.7 ± 7.4) scores, (17.2 ± 3.0) scores vs. (30.8 ± 5.0) scores, (16.1 ± 5.1) scores vs. (30.4 ± 4.9) scores and (17.9 ± 4.0) scores vs. (32.1 ± 5.5) scores, and there were statistical differences (P0.05). Conclusions The fentanyl, sufentanil and oxycodone combined with propofol of intravenous anesthesia in patients underwent artificial abortion can reduce propofol dose, shorten recovery time, improve positive affective score, decrease negative affective score and strengthen the analgesic effect, and doesn't increase the adverse reaction. The respiratory and circulatory inhibition effects of different analgesics combined with propofol of intravenous anesthesia were similar, but oxycodone can increase positive affective score.
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Objective To investigate the potential of a novel preservation solution,raffinose-low potassium dextran lung preservation solution with blood (BR-LPDS) in the preservation of the isolated lungs in rats,when compared to low-potassium dextran solution (LPDS).Methods Fifty donor lungs of Sprague-Dawley rats were randomly flushed with either R-LPDS (R-LPDS group,n =25) or RLPDS modified by the addition of blood (BR-LPDS group,n =25).After reperfusion,the double lungs were kept half inflate and then the pulmonary artery and bronchus were clamped.Then the grafts were flushed with and submerged in cold preservation solution at 4 C for 24 h.And they were excised for measurement of wet-to-dry ratio,as well as histologic examination to evaluate pulmonary edema,inflammation and cleaved caspase-3 expression at 0,2,4,5,6,8,10,12,14,16,24 h.Results As compared with the R-LPDS group,the mean wet-to-dry ratio of lungs in the BR-LPDS group was significantly reduced from 4 to 10 h after reperfusion.Upon histologic examination,less inflammatory cell aggregates and lower caspase-3 activity were seen in the lungs of the BR-LPDS group from 10 to 12 h and 10 to 14 h after reperfusion,respectively.Conclusion The addition of blood to the R-LPDS solution was shown to be more effective in reducing swelling,inflammation and caspase-3 expression of donor lungs than the R-LPDS solution.Further investigation is needed to evaluate lung preservation in BR-LPD solution as a viable option for transplant.