摘要：Background Autophagy,a dynamic and efficient process of self-digestion in vivo,has been proven to be beneficial for cardiac protection during MI process via removing the additional protein and damaged organelles in the heart.Taxifolin (Tax),a common plant flavonoid,has been widely used for the treatment of myocardial infarction.However,the underlying mechanism of Tax is largely unknown.Methods Murine arterial cardiomyocytes HL-1 cells were pretreated with Tax and then exposed to hypoxia environment.CCK-8 was performed for the determination of cell viability.Monodansylcadaverine (MDC) and Microtubule-associated protein 1A/1B-light chain 3 (LC3) were analyzed by immunofluorescence staining.The relative gene expressions of Hypoxia Inducible Factor-1 (HIF1-a) and Heme Oxygenase-1 (HO-1) were determined by qRT-PCR.Results Tax at 100 μm for 6 h has the maximal effect to avoid reducing the cell viability excessively and significantly abolished hypoxia-induced cell death.Both of the MDC and LC3 immunofluorescence staining revealed markedly increase of expression of autophagy with pretreatment of Tax.Finally,qRT-PCR showed the upregulation of HIF1-a and HO-1 with Tax.Conclusions Taken together,Tax might be a potential candidate for the treatment of MI by promoting cardiomyocyte autophagy via the activation of HIF1-a and HO-1.

摘要：Background In recent years, it is found that the polymorphisms of genes which are involved in the pharmacokinetic and pharmacodynamie pathways play important roles in the clinical anticoagulation treatment with warfarin. The aim of the study was to investigate the impact of the genetic polymorphism of r-glutamie acid carboxylase (gamma-glutamyl carboxylase gene, GGCX) on the response of warfarin initial anticoagulant therapy. Methods Seven hundred and ninety-eight Chinese Han patients who received valve replacement surgery and orally taken warfarin in long term for anticoagulant therapy in Guangdong General Hospital from 2000 to 2008 were enrolled in the study, a polymorphic SNPs point (rs699664) of GGCX was selected, and SnaPshot was adopted to perform single nucleotide polymorphism (SNP) test, and by grouping according to genotype, GGCX average daily dose of warfarin, time for PT-INR to reach the target value and differences in the incidence of excessive coagulation between different genotypes were compared respectively. Hardy-Weinberg genetic equilibrium test was applied for population representative test.Results Within the 20 days of warfarin initial therapy, male average daily dose of warfarin (2.92 ± 1.18 mg/d) was apparently higher than that of female (2.64 ± 0.98 mg/d), while there were no significant differences in the average time required for PT-INR to reach the target value ( > 1.8) and the excessive coagulation ratio at the initial therapy stage between male and female. And there were no significant differences in the average daily dose of warfarin, time to reach the target value and excessive coagulation ratio among different GGCX genotypes. Conclusions GGCX genovariation had no significant impact on the warfarin daily dose within the 20-day initial therapy of Chinese Han Population, and for the conventional dosage program, the risk of bleeding in the GGCX mutation individuals did not increase obviously at the initial administration period.

摘要：Objective The study will explore effects of the autoantibodies against AT1 receptor and angiotensin Ⅱ on the refractory hypertension. Methods Seventy-seven patients (46 men and 31 women) with essential hypertension were divided into groups of refractory hypertension (RH) and hypertension (HT) according to the 1999 WHO -ISH Guidelines for the Management of Hypertension. Forty normotensives (22 men) were recruited as controls.The mean age was 54. 3 ± 13 years old in RH group,53.5±9 years old in HT group and 51.2±11.9years old in normotensives (NT) group. The mean blood pressure was 154.2 ± 9.4/98.4 ± 8.2 mmHg in RH group and 130.1 ±7.6/80.5 ±6.7 mmHg in HT group after combination drug therapy of hypertension for 4 weeks. Blood pressure in NT group was 120. 8 ± 11.7/76. 4 ± 7.2 mmHg. The epitope of the 2nd extracellular loops of AT1 receptor was synthesized and used as antigens to screen the autoantibodies by ELISA. Plasma angiotensin (Ang) Ⅱ were examined by a radioimmunoassay. Results The autoantibodies against AT1 receptor were positive in 18 (46. 15% ) patients with RH, in 4 (10. 5 % ) hypertension and in 3 (7.5 % ) normotensives, P ＜ 0.01. Ang Ⅱwas 57.01 ± 52.63 pmol/L in patients with RH. Both the autoantibodies positive and the Ang Ⅱ increasing were 4 (10. 3 %) cases, both normal were 7 (17.9% ) cases, the autoantibodies positive or Ang Ⅱ in creasing was all of 14 (35.9 % ) cases (χ2 =0. 09,P ＞ 0. 05) There was no relationship between the autoantibodies against AT1 receptor and the angiotensin Ⅱ in refractory hypertension. Conclusion The autoantibodies against AT1 receptor and Ang Ⅱ might be two independent factors in developing of refractory hypertension. The findings suggest that AT1 receptor antagnist used in the treatment of refractory hypertension might have an important value.

摘要：Background Myocardial fibrosis plays a critical role in the process of diabetic cardiac remolding. MicroRNAs (miRNAs) are endogenous,small non-coding RNAs that negatively regulate gene expression in diverse biological and pathological processes.However,the roles of miRNAs in myocardial fibrosis have not been well elucidated. In the present study, miRNAs profiles in the fibrotic myocardium of db/db mice and miRNAs expression in TGF-β1-stimulated mouse cardiac myofibroblasts was examined.Methods Heart function of 18-week-old db/db mice and db/m control mice was detected by echocardiography.miRNA expression profile in diabetic myocardium was detected by miRNA microarray. Quantitative real-time PCR was used to determine the expression of fibrosis-related genes and miRNA precursors of interest.Western blot was used to detect the levels of fibrosisrelated proteins, activated Smad3 and total Smad3. Results The result of echocardiography showed that left ventricular systolic and diastolic function was impaired in 18-week-old db/db mice without significant change of ejection fraction (EF) and fractional shortening (FS).Fibrosis-related genes expression was upregulated and the amount of phosphorylated Smad3 was increased significantly in the diabetic myocardium. miRNAs dysregulation was shown in diabetic myocardium,sixty-eight miRNAs,including miR-208b,miR-29b,miR-26b and miR30e,were increased over two-fold,meanwhile,sixty-two miRNAs were decreased more than two-fold in the myocardium of db/db mice compared to db/m controls.In parallel with a significant upregulation of Col1a1,Col3a1 and CTGF miRNA expression,miR-208b,miR-29b,miR-26b and miR-30e precursors were also shown to be upregulated in TGF-β1-induced C57bl/6 mouse cardiac myofibroblasts. Conclusions microRNAs were dysregulated in diabetic myocardium,with the activation of TGF-β/smad3 pathway,contributing to diabetic myocardial fibrosis.

摘要：Objectives To study the gene expression of human vascular endothelial cells (HUVEC) treated by ouabain in pathological concentration. Methods The response of endothelial cells to ouabain of 1.8 nmol/L was explored with a complementary DNA microarray representing 8 464 different human genes. Results The results of mRNA profiles analysis indicated that 129 of the genes were differently expressed, 26 were upregulated. Conclusions The pathological role of ouabain on HUVEC may be involved in the controlling of DNA transcription、protein translation、 metabolism and signal transduction.

摘要：Coronary heart disease(CHD)is a major health problem in many countries and its pathogenesis is not yet fully understood,contributing to significant morbidity and mortality.Accumulated evidence manifest clearly that CHD is determined by a complex interplay of genetic and environmental factors.Many clinical data have showed that the renin-angiotensin system(RAS)involved in many cardiovascular diseases,such as hypertension and CHD.Angiotensinogen(AGT)is the key components of the RAS system,and two gene polymorphisms of AGT had been detected of the CHD risk:M235T and T174M. This article reviews the effects of ACT gene polymorphisms on the CHD.

摘要：Background Cardiovascular diseases (CVD) are less prevalent in postmenopausal women received estrogen replacement therapy (ERT) than those who did not receive ERT.Previous study has shown that the increase of nitric oxide (NO) synthesis is one of the cardioprotective effects of estrogen.This study investigated the effects of estrogen and L-arginine (L-Arg) on serum NO concentrations and the possible regulatory role in endothelial nitric oxide synthase (eNOS) expression in aortas of aged rats. Methods Fifty aged female wistar rats (18-20 months) were randomly divided into five groups (n =10):Sham group (sham operated,0.9 ％ NaCl 10 μg every three day for 4 months),OVX group (ovariectomized,0.9 ％ NaCl 10 μg i.m every three day for 4 months),OVE group (ovariectomized + 17β-estradiol 10 μg i.m every three day for 4 months),OVE + L-Arg group (ovariectomized + 17β-estradiol 10ug i.m every three day + 2.25 ％ L-Arg contained in drinking water every day for 4 months) and L-Arg group (ovariectomized + 2.25 ％ L-Arg contained in drinking water every day for 4 months).NO concentration and the expression of eNOS mRNA in aorta were measured after 4 months.Results Serum NO synthesis did not alter after ovariectomized (P =0.362),but were increased in OVE group,L-Arg group and OVE + L-Arg group compared with OVX group (P ＜ 0.05,P ＜ 0.05,P ＜ 0.01,respectively).NO concentration also increased in OVE + L-Arg group when compared with OVE group (P ＜ 0.05) or L-Arg group (P ＜ 0.05).There was no significant difference in eNOS mRNA expression in aortas of aged rats between sham,OVX,OVE,OVE + L-Arg and L-Arg group (F =0.550,P =0.700).Conclusions Estrogen treatment and LArg supplementation increase serum NO synthesis, but do not upregulate eNOS mRNA expression in aortas of aged rats.

摘要：Background Hyperuricemia as an independent predictor for presence of coronary artery disease (CAD)has been studied insufficiently. In this study, we evaluated the predictive value of hyperurieemia for the severity of coronary artery disease. Methods A total of 683 patients undergoing elective percutaneous coronary intervention (PCI) were prospectively observed and were divided into two groups (hyperuricemie group, n = 216, and normouricemic group, n = 467). Hyperuricemia (HUA) was defined as an serum uric acid level > 7 mg/dL in males and > 6 mg/dL in fe-males. Severe CAD was defined as triple-vessel disease or left main disease. Results One hundred and eighteen (55%) severe CAD occurred in the hyperuricemic group and 211(45%) in the normouricemic group (P = 0.02). The median uric acid levels of the severe CAD patients were significantly higher than secondary CAD (single vessel disease or two-vessel disease) patients (379 ± 111 vs 360 ± 105, P = 0.02). Multivariate logistic regression analysis, after ad-justing for potential confounding factors, showed that HUA was an independent risk factor of coronary artery disease (odds radio = 1.63, 95% confidence interval, 1.02-2.61, P = 0.040). Moiety of in-hospital complications such as a cute heart failure ( 17.6% vs. 6.2%, P < 0.001), hypotension (3.8%, vs. 1.3%, P = 0.04), contrast induced nephropa-thy (CIN) (7.4% vs. 1.3%, P < 0.001) after PCI, were significantly higher in hyperuricemic groups. Conclusions Hyperuricemia was an independent predictor for severe coronary artery disease (triple-vessel disease or left main dis-ease).

摘要：Objectives To study the effects of bradykinin (BK) B2 receptor blockade on infarct size and hemodynamics after myocardial infarction (MI) in rats with angiotensin-converting enzyme (ACE) inhibition therapy.Methods MI was produced by ligating the left coronary artery.The effects of enalapril(500μg/kg·day),enalapril(500μg/kg·day) with BK B2 receptor antagonist Hoe-140(500μg/kg·day),angiotensin Ⅱ(Ang Ⅱ) type 1(AT1) receptor antagonist losartan (3 mg/kg·day) on infarct size,left ventricular systolic pressure(LVSP),cardiac output index (CI) and stroke volume index (SVI) were observed in rats after MI.Treatments were started on the 2nd day after MI and continued for another 6 weeks.Results Enalapril reduced infarct size and improved CI and SVI compared with the untreated MI group (P＜0.05 ),and these effects of enalapril were significantly blunted by concomitant treatment with Hoe-140 (P＜0.05).Losartan was less effective than enalapril.LVSP were unchanged in the three treatment groups.Conclusions BK can reduce infract size and improve hemodynamics in rats following MI.The cardioprotective effects of ACEI partly result from the action of BK exerted through the B2 receptor.

摘要：Objectives To study the change in plasma hemoglobin concentration in elderly patients with primary hypertension and/or type 2 diabetes complicated with end-stage renal disease(ESRD) determined by estimated glomerular filtration rate. Methods Two hundred and thirty cases of Chinese patients aged 60 years or older with primary hypertension and/or type 2 diabetes complicated with chronic kidney disease were enrolled in the study. Patients with chronic kidney(7.80±3.14mL·min-1·1.73m-2) and non-ESRD group with estimated glomerular filtration rate 15mL·min-1·1.73m-2(29.76±12.90mL·min-1·1.73m-2)or higher. The plasma hemoglobin concentration was compered between the above two groups retrospectively. Results There was significant decrease in plasma hemoglobin concen-tration in ESRD group compared with non-ESRD group(74. 4 ± 22. 5 g/L vs 100. 8 ± 23.0 g/L, P < 0. 05). After stratification by sex, there was also significant decrease in plasma hemoglobin concentration both in male and female of ESRD groups compared with their respective non-ESRD groups(77.2 ± 22. 0 g/L vs 104. 9 ± 20. 7 g/L; 69. 7 ± 22. 8 g/L vs 96. 4 ± 24. 8 g/L, P < 0. 05, respectively). Plasma hemoglobin concentration was positively related to esti-mated glomerular filtration rate significantly in patients with ESRD (P < 0. 05). Condusions Plasma hemoglobin con-centration is decreased significandy, and is positively related to estimated glomerular filtration rate significantly in elder-ly patients with primary hypertension and/or type 2 diabetes complicated with ESRD determined by estimated glomeru-lar filtration rate.

摘要：Background Premature ventricular contractions (PVCs) are associated with an increased risk of morbidity and mortality.Therefore,this study was aimed to assess the prevalence and risk factors of frequent PVCs in Guangzhou communities.Methods Our population-based study included 12013 adults from the permanent residents aged 35 years old and above in 20 communities of Yuexiu District and Panyu District in Guangzhou.Standard 12-lead ECG was performed in 11,634 residents.PVC count was determined by 24-hour Holter ECG in 8172 residents.We performed multivariable regression analysis using stepwise backward selection to identify factors independently associated with frequent PVCs (≥1％ of the total beats).Results Among those who received 12-lead ECG,4,095 were men,accounting for 35.2％ of 11634 participants.1.6％ the residents had PVCs and median age was 59 years.2852 (34.9％) were male in 8172 subjects who received 24-hour Holter ECG and 1239 of the 8172 subjects (15.2％) were diagnosed with PVCs by single-lead dynamic electrocardiogram.2.9％ subjects were accounted PVCs exceeded 1％ of the total heartbeats,0.2％ subjects were accounted PVC exceeded 10％ of the total heartbeats.The multivariable analysis showed that four factors related with frequent premature ventricular contractions included aging (odds ratio (OR) 1.027;95％ CI 1.015 to 1.039),male gender (1.533;95％ CI 1.162 to 2.023),high diastolic pressure (1.027;95％ CI 1.015 to 1.039) and long QTc interval (1.016;95％ CI 1.005 to 1.027).Besides,frequent vegetable intake (0.225;95％ CI 0.064 to 0.795),high LDL (0.787;95％ CI 0.684 to 0.906) and high TG (0.873;95％ CI 0.771 to 0.989) were the protective factors of frequent PVCs.Conclusion PVCs is prevalent in Guangzhou communities.The factors such as age,gender,blood pressure,QTc,vegetable intake,LDL and TG care associated with PVCs.

摘要：Background Recent researches have found that stains can improve acute myocardial ischemia reperfusion injury which is achieved by inhibiting inflammatory reaction. Xuezhikang is extracted from red rice, a tailormade Chinese crude drug. Main component of Xuezhikang that can inhibit blood-fat is statins. Methods Forty healthy SD rats (half male and half female,200 g or so) were randomly divided into four groups:A:normal control; B:sham operation; C:MIR group; D:Xuezhikang group.The acute myocardial ischemia reperfusion injury model was produced.Infarct sizes,MYO,CK-MB,cTnI,IL-10 and IL-18 were detected after reperfusion.Results Compared with C and D group, in A and B group, infarct size were increased significantly (P ＜0.01),the level of serum MYO,CK-MB,cTnI were increased significantly (P ＜ 0.01),the level of IL-10 were decreased significantly (P ＜ 0.01) and IL-18,CRP were increased significantly (P ＜ 0.01).Compared with C group,infarct size were decreased significantly (P ＜ 0.05),the level of serum MYO,CK-MB and cTnI were increased significantly (P ＜ 0.05),the level of IL-10 were increased significantly (P ＜ 0.05) and IL-18 were decreased significantly (P ＜ 0.05). The level of IL-10 and IL-18 were no difference between A and B group.Conclusion The application of Xuezhikang capsules on rats before the operation of myocardial ischemia reperfusion can lessen inflammatory reaction and reduce infarct sizes and protect acute myocardial ischemia reperfusion.

摘要：Objectives To investigate the effects of simvastatin on membrane ionic currents in left ventricular myocytes of rab-bit heart suffering from acute myocardial infarction (AMI), so as to explore the ionic mechanism of statin treatment for antiarrhythmia. Methods Forty-five New Zealand rabbits were randomly divided into three groups: AMI group, simv-astatin intervention group (Statin group) and sham-operated control group (CON). Rabbits were infarcted by ligation of the left anterior descending coronary artery after administration of oral simvastatin 5 mg · kg-1 · d-1 (Statin group) or placebo (AMI group) for 3 days. Single ventricular myocytes were isolated enzymatically from the epicardial zone of the infracted region 72 h later. Whole cell patch clamp technique was used to record membrane ionic currents, inclu-ding sodium current (Ina), L-type calcium current (Ica-L) and transient outward potassium current (Ito). Results ① There was not significant difference in serum cholesterol concentration among three groups. ② The peak Ina current den-sity (at -30 mV) was significantly decreased in AMI group (-25.26±5. 28, n = 13), comparing with CON (-42. 78±5.48, n = 16), P < 0. 05, while it was significantly increased in Statin group (-39. 83±5. 65 pA/pF, n = 12) comparing with AMI group, P <0. 01; The peak I Ca-L current density (at 0 mV) was significantly decreased in AMI group (- 3.43±0. 92 pA/pF, n = 13) comparing with CON (- 4. 56±1.01 pA/pF, n = 15), P < 0. 05, while it was significantly increased in Statin group (-4. 18±0. 96 pA/pF, n = 12) comparing with AMI group, P <0. 05; The Ito current density (at + 60 mV) was significantly decreased in AMI group (11.41±1.94 pA/pF, n = 13) compa-ring with CON (17. 41±3. 13 pA/pF, n = 15), P <0. 01, while it was significantly increased in Statin group (16. 11±2. 43 pA/pF, n = 14) comparing with AMI group, P < 0. 01. Conclusions AMI induces significant down-regula-tion of Ina, I Ca-L and Ito. Pretreatment with simvastatin could attenuate this change without lowering the serum cholester-ol level, suggesting that simvastatin could reverse this electrical remodeling, thus contributing to the ionic mechanism of statin treatment for antiarrhythmia.

摘要：Background Total anomalous pulmonary venous connection (TAPVC) is the most important anomaly of the pulmonary veins. Many surgical techniques have been proposed to establish a widely patent connection between the common pulmonary vein and the left atrium while avoiding post-repair pulmonary vein stenosis. However, for patients with hypoplastic common pulmonary vein, the traditional techniques may be limited by the vessel's length and size.The anastomotic technique can cause trauma to the pulmonary venous endothelium. We propose a novel anastomotic technique: for the primary surgical repair of supra-cardiac TAPVC where the venous incision is extended onto the vertical, vein and a suture-less anastomosis is performed. Methods From January 2000 to December 2008, 143 patients were surgically treated for TAPVC at Guangdong Cardiovascular Institute, including 59 (41.2 %) cases of supracardiac type, 63 (44.1%) of cardiac type, 6 (4.2 %) of infraeardiac type, and 15 (10.5 %) of mixed type.Twenty one of 59 supracardiac TAPVC were undertaken with the extended anastomotic technique through the pericardial oblique sinus approach. This group included 9 boys and 12 girls. Aged at presentation ranged from 2 days to 13 years with a median of 4 months. Weight ranged from 2.3 kg to 25 kg with a median of 4.8 kg. Results There was no early or late mortality. One case failed to follow-up. The mean aortic cross-clamp time was 42.5 ± 6.4 minutes. The cardiopulmonary bypass time was 75.6 ± 7.2 minutes. Deep hypothermic circulatory arrest was not employed in any case. Intraoperative echocardiogram demonstrated a widely patent anastomosis between the common pulmonary vein and the left atrium. The velocities across the anastomosis were in the range of 0.50 to 0.75 m/s. Four cases required delayed sternal closure due to hemodynamic instability. The mean ICU stay was 8.7 ± 5.3 days with a mean period of artificial ventilation of 4.2 ± 2.9 days. The duration of follow up was 3.8 ± 1.8 years with one case lost to follow up.Assessments with transthoracic echocardiography showed the velocities across the anastomosis were in the range of 0.55 to 0.75 m/s. Conclusions Extended anastomosis with suture-less technique can be an effective method for primary repair of supracardiac TAPVC. TAPVC is the most important anomaly of the pulmonary veins.

摘要：Background Clopidogrel is beneficial after acute coronary syndrome.Recent studies suggest the superiority of prasugrel compared with clopidogrel.The enhanced platelet inhibition with prasugrel lead to a reduction in major adverse cardiovascular events in patients with moderate to high risk acute coronary syndrome scheduled for PCI.However,prasugrel showed signs of increased bleeding potential.We performed a meta-analysis to assess clinical safety and efficacy of prasugrel in patients with acute coronary syndrome.Methods We systematically searched PubMed,ISI Web of Knowledge,Cochrane Central Register of Controlled Trials,clinicahrials,gov,proceedings of major US and European cardiology meetings,China National Knowledge Infrastructure(CNKI)databases 2000-2010 and reviews,reference lists of relevant articles.The search strategy paired the term"prasugrel""clopidogrel"with the following:"acute coronary syndrome""percutaneous coronary intervention"We conducted a meta-analysis of randomized double-blind trials that evaluated clinical outcomes in patients with acute coronary syndrome.Two reviewers independently assessed the trials.Differences were resolved by consensus.Results A total of 2 trials with 14512 patients were available for analysis.Overall,prasugrel appeared significantly superior to clopidogrel for the risk of MACE(OR =0.820.74-0.90,P < 0.0001),stent thrombosis(OR = 0.470.35-0.62,P < 0.00001),death(OR = 0.850.78-0.93,P =0.0003),and myocardial infarction(OR = 0.760.68-0.85,P < 0.00001),without any significant difference in stroke(P= 0.85).However,major bleeding associated with non coronary artery bypass grafting Thrombolysis in Myocardial Infarction related to prasugrel(OR = 1.321.03-1.67,P = 0.03).Condusions Prasugrel is superior to clopidogrel for acute coronary syndrome,while causing more bleedings.

摘要：Objectives To determine the validity and applicability of the global registry of acute coronary events (GRACE) pre-diction model for in-hospital mortality in all forms of acute coronary syndrome (ACS) in a sub population of Chongqing. Methods Data of 669 ACS patients were collected retrospectively from Jan 2005 to Apr 2008 and were re-corded on a standardized case report form. For each patient the GRACE risk score (GRACE RS) was calculated (using the GRACE calculator available from the grace website) using specific variables collected at admission. Patients with missing data and those transferred from other hospitals were excluded. Receiver operating characteristic (ROC) curves were plotted for the GRACE risk score. Results Among 576 ACS patients, 98 (17.01%), 36 (6. 25 %), and 442 (76. 74 %) presented with ST-elevation myocardial infarction (MI), non-ST elevation MI and unstable angina, re-spectively. The GRACE risk score could not be determined in 91 (9. 3 %) patients due to missing data or for patients who were transferred from other hospitals and were excluded from the analysis. The median GRACE risk score was 133 (interquartile range: 92 - 174) and, the in-hospital rates of death and death/(re-) MI were 6. 1% and 7.6 %, respec-tively. The GRACE risk score demonstrated excellent discrimination (c-statistic = 0. 86, 95 % CI 0. 79 - 0. 91, P < 0. 001) for in-hospital death/ (re) -MI. Conclusions The GRACE RS study had a good predictive accuracy for death or MI across the wide range of ACS in this population. It may be a useful risk stratification tool that helps identify high-risk patients who will benefit most from myocardial revascularization and low risk patients who may be spared from un-dergoing more aggressive interventional treatment.

摘要：Objectives To investigatethe influences of electric signals applied during absoluterefractory period(ARP)on the contractility of isolatedpapilary muscle from rabbits.Methods Papillarymuscle was exercised from the right yentricle and waspaced at 1 Hz.Biphasic square wave current pulse wasdelivered during the absolute refractory period(calledCCM)in isolated,superfused,isometrically contractil-ity rabbit papillary muscle.The peak tension(PT)ofpapillary muscle,as well as maximum positive tensionchange(+dT/dtmax),were observed.ResultsCompared with the baseline,both PT and+dT/dtmaxsignificantly increased during CCM stimulation by18.2%and 21.4%respectively(P＜0.05).In ad-dition,PT increased significantly with one or two beatsfollowing CCM signal application and reached a newsteady state level after a few beats.Once the CCM signals were turned off,the PT returned to the approximatelv baseline level(P＜0.05).Moreover,the effectof CCM on PT was dose-response to voltage.Theobvious effect was at higher voltage.No effect was ob-served at lower voltage.Conclusions Electric signalsdelivered during the absolute refractory period canrapidly enhance the contractility of myocardium,whichsuggests that CCM signal is a novel potent method forcontractility modulation.