Objective To explore the molecular mechanism of prolonged atrial repolarization in rats with reperfusion atrial arrhythmia.Methods Sixteen Langendorff isolated heart perfusion models made by male SD rats were randomly divided into control group(group C,n = 8)and hypothermic ischemia-reperfusion group(group IR,n = 8).According to the occurrence of atrial arrhythmia after reperfusion,group IR was further subdivided into reperfusion non-atrial arrhythmia subgroup(group N-RAA)and reperfusion atrial arrhythmia subgroup(group R-AA).Group C was perfused with 37℃K-H solution for 120 min.In group IR,the isolated heart was perfused with 37℃K-H solution for 30 min and stopped,and the isolated heart was perfused with 4℃Thomas solution(20 mL/kg)for 60 mins.When the heart stopped for 30 mins,the isolated heart was perfused with a half dose of 4℃Thomas solution(10℃).During cardioplegia,the isolated heart was protected by low temperature Thomas solution(4℃),and then reperfused for 30 mins with 37℃K-H solution.The monophasic action potential(MAP)of the right atrium was recorded at balanced perfusion for 30 mins(T0),balanced perfusion for 105 mins in group C/reperfusion for 15 mins in group IR(T1)and balanced perfusion for 120 mins in group C/reperfusion for 30 min in group IR(T2);The duration of 50%and 90%repolarization of monophasic action potential(MAPD50 and MAPD90)was measured.After electrophysiological monitoring,the expression of Kir2.1 and CaMKⅡ in right atrium was detected by Western blot.Results Compared with T0,MAPD50 and MAPD90 at T1 and T2 were significantly prolonged in group R-AA(P<0.05),and MAPD90 at T1 and T2 in group R-NAA and group R-AA were significantly longer than those in group C(P<0.05).Compared with group R-NAA,MAPD50 and MAPD90 in group R-AA were significantly prolonged at T1 and T2(P<0.05).The results of Western blot showed that the expression of Kir2.1 in group R-NAA and group R-AA was significantly lower than that in group C(P<0.05),and that in group R-AA was significantly lower than that in group R-NAA(P<0.05).The expression of CaMKⅡ in group R-NAA and group R-AA was significantly higher than that in group C(P<0.05),and the expression of CaMKⅡ in group R-AA was significantly higher than that in group R-NAA.Conclusion The prolonged duration of atrial repolarization in rats with hypothermic ischemia-reperfusion atrial arrhythmia may be related to the down-regulation of Kir2.1 expression and the up-regulation of CaMKⅡ expression.

Objective:To evaluate the effect of rat cardiac fibroblasts (RCF) on the expression of connexin43 (Cx43) in H9c2 cells during hypothermic hypoxia/reoxygenation.Methods:H9c2 cells cultured in vitro were divided into 4 groups ( n=12 each) using the random number table method: control group (group C), hypothermic hypoxia/reoxygenation group (group HHR), RCF co-culture group (group Co) and RCF co-culture plus hypothermic hypoxia/reoxygenation group (group Co+ HHR). Group C was incubated at 37℃ in 5% CO 2 + 95% air for 5 h. Group HHR was incubated at 4 ℃ in 5% CO 2 + 95% N 2 for 1 h and then at 37 ℃ in 5% CO 2 + 95% air for 4 h. In group Co and group Co+ HHR, H9c2 cells 0.3×10 5 cells/well were inoculated in the lower chamber and RCF 0.6×10 5 cells/well in the the upper chamber of a transwell ? culture dish.Group Co was incubated at 37 ℃ in 5% CO 2 + 95% air for 5 h. Group Co+ HHR was incubated at 4℃ in 95% N 2 + 5% CO 2 for 1 h, and then incubated at 37 ℃ in 5% CO 2 + 95% air for 4 h. The mortality rate of H9c2 cells was measured by trypan blue staining, the expression of Cx43 and extracellular signal-regulated protein kinases 1/2 (ERK1/2) by immunofluorescence, and the expression of Cx43, phosphorylated Cx43, ERK1/2 and phosphorylated ERK1/2 by Western blot. Results:Compared with group C, the mortality rate of H9c2 cells was significantly increased, the expression and phosphorylation of Cx43 were decreased, and the expression and phosphorylation of ERK1/2 were increased in group HHR ( P<0.05), and no significant change was found in the mortality rate of H9c2 cells or expression and phosphorylation of Cx43 and ERK1/2 in group Co ( P>0.05). Compared with group Co, the mortality rate of H9c2 cells was significantly increased, and the expression and phosphorylation of Cx43 and ERK1/2 were decreased in group Co+ HHR ( P<0.05). Compared with group HHR, the mortality rate of H9c2 cells was significantly increased, and the expression and phosphorylation of Cx43 and ERK1/2 were decreased in group Co+ HHR ( P<0.05). Conclusions:RCFs can decrease the expression and activity of Cx43 in H9c2 cells during hypothermic hypoxia/reoxygenation, and the mechanism may be related to the down-regulation of ERK1/2 expression and inhibition of ERK1/2 activity.

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.

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.

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.

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.

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.

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-PCL_max) 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-PCL_max 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.

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.

Objective To investigate the inpatients′satisfaction with the hospital environment,medical process,medical skills and service attitudes,in order to provide evidence for improving the hospital cultural construction and patients′satisfaction level.Methods According to the stratified sampling by the department,the study investigated 521 inpatients from a second-class hospital using questionnaire survey.Results Approximately 62.2% of the participants were satisfied with the “hardware”of the hospital culture and 66.8% were satisfied with the “software ” of the hospital culture.However,there were no statistical differences between these satisfactions (χ2 =0.046,P >0.05).Conclusions A considerable proportions of the participants are not satisfied with the current hospital culture.Thus,the hospitals should enhance their cultural construction and education,as well as improve the medical procedures and technical skills,in order to promote patients′rehabilitation and satisfaction level.