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Aim To investigate the effects of lysophosphatidic acid on ischemia / reperfusion injury(IRI)and TRPV1 expression in isolated mouse heart.Methods The IRI model of isolated mouse heart was established by Langendorff device.The hearts in sham group were continuously perfused for 100 min.The hearts in IR group were stabilized for 10 min followed by no perfusion for 30 min and reperfusion for 60 min.Exogenous LPA was added in the K-H solution during IR in IR+LPA group while HA130, an LPA synthesis inhibitor, was intraperitoneally injected before IR in IR+HA130 group.The infarct volume was measured by TTC staining, the determination of LPA and LDH levels in coronary effluent and LPA concentration in serum was measured by ELISA method.Finally, the expression levels of pTRPV1/TRPV1 and Bcl-2/Bax in myocardial tissues were determined by Western blot.Results Compared with sham group, IR caused evident myocardial infarction and increased the levels of LDH and LPA in coronary effluent.The increase of LPA was linearly correlated with myocardial infarction volume.In addition, the protein levels of pTRPV1 and TRPV1 in myocardium increased, while the ratio of Bcl-2/Bax decreased.The myocardial injury in IR+LPA group was aggravated.In contrast, myocardial IRI was reversed in IR+HA130 group.Conclusions Myocardial ischemia-reperfusion induces the release of LPA, which aggravates myocardial post-ischemic injury, while the inhibition of LPA release exerts cardioprotective effects.The underlying mechanisms might be related to the regulation on cardiac TRPV1 expression and apoptotic signals.
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ABSTRACT Purpose The present study explored the influence of liraglutide on remote preconditioning-mediated cardioprotection in diabetes mellitus along with the role of nuclear factor erythroid 2-related factor 2 (Nrf2), hypoxia inducible factor (HIF-1α) and hydrogen sulfide (H2S). Methods Streptozotocin was given to rats to induce diabetes mellitus and rats were kept for eight weeks. Four cycles of ischemia and reperfusion were given to hind limb to induce remote preconditioning. After 24 h, hearts were isolated and subjected to 30 min of ischemia and 120 min of reperfusion on Langendorff system. Liraglutide was administered along with remote preconditioning. Cardiac injury was assessed by measuring the release of creatine kinase (CK-MB), cardiac troponin (cTnT) and development of left ventricular developed pressure. After ischemia-reperfusion, hearts were homogenized to measure the nuclear cytoplasmic ratio of Nrf2, H2S and HIF-1α levels. Results In diabetic rats, there was more pronounced injury and the cardioprotective effects of remote preconditioning were not observed. Administration of liraglutide restored the cardioprotective effects of remote preconditioning in a dose-dependent manner. Moreover, liraglutide increased the Nrf2, H2S and HIF-1α levels in remote preconditioning-subjected diabetic rats. Conclusions Liraglutide restores the lost cardioprotective effects of remote preconditioning in diabetes by increasing the expression of Nrf2, H2S and HIF-1α.
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Animals , Rats , Myocardial Reperfusion Injury/prevention & control , Ischemic Preconditioning, Myocardial , Diabetes Mellitus, Experimental/drug therapy , Hydrogen Sulfide , Hydrogen Sulfide/pharmacology , Myocardial Infarction , Signal Transduction , Rats, Wistar , NF-E2-Related Factor 2 , Liraglutide/pharmacologyABSTRACT
Objective To explore the protective effect of ginsenoside Rb1 on the myocardial ischemia / reperfusion (I / R) injury in rats in vitro. Methods Totally 60 adult male SD rats were randomly divided into 6 groups:sham group,I / R group,ginsenosde Rb1 pretreatment groups(at the doses of 1 μmol / L,5 μmol / L,10 μmol / L and 20 μmol / L,respectively), 10 in each group. The Langendorff perfusion system was used to establish I / R model. The Lab Chart electrophysiological system was used to monitor real-time heart function by monitoring heart rate (HR), left ventricular development pressure (LVDP) and left ventricular development pressure (± dp / dtmax). TTC staining method was used to measure myocardial infarct size. The Western blotting were used to assay Beclin 1, LC3, p62 and Lamp 2 expression, respectively. The immunohistochemistry were used to assay Beclin 1 expression. Results Ginsenoside Rbl of all the four different concent rations improved the decrease of LVDP and ± dp / dtmax arising from myocardial I / R injury. Meanwhile, ginsenoside Rbl significantly decreased the area of cardial infarction. Ginsenoside Rb1 (10 μmol / L) precondition group protected the heart most significantly (P<0. 05). The expression of Beclin 1 with I / R increased significantly in the cytoplasm of cardiomyocytes. Moreover, Beclin 1 expression decreased after addition pretreatment with ginsenoside Rb1 (10 μmol / L) (P < 0. 05). Compared with sham group, we found that the autophagic flux was impaired in I / R group which the expression of Beclin 1, LC3 and p62 increased significantly, as well as the expression of Lamp 2 decreased significantly. On the other hand, pretreatment with ginsenoside Rb1 (10 μmol / L) could reverse impaired autophagic flux (P < 0. 05). Conclusion Ginsenoside Rbl demonstrates pharmacological preconditioning effect and protects against myocardial I / R injury by improving damaged-autophagy flux, the dose of 10 μmol / L precondition protectes the heart most significantly.
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Abstract AIM To compare the amount of cardioprotection induced by a single exercise session with those achieved after an 8-week aerobic exercise training following ischemia reperfusion injury in rats. METHODS Twenty-five male Wistar rats (250-300g) were assigned into a group submitted to physical training (TR; n=12) or a single maximal exercise session (EXE; n=13). Following sedentarism or physical training (8 weeks, 5 sessions/wk, 1h/session at 70% of maximal speed) both groups performed a maximal exercise test. Then, groups were submitted to ischemia reperfusion injury (30 min/1h) through an isolated heart protocol, in which left ventricle developed pressure was measured. RESULTS The TR group presented greater maximal oxygen consumption compared to the EXE group (77.25±20.41 vs 41.32±25.86 ml/Kg/min; P=0.003). Regarding left ventricle developed pressure, no differences were detected between groups at baseline (TR: 89.78±24.40 vs EXE: 81.37±31.84 mmHg; P=0.48). However, after reperfusion, the TR group presented superior intraventricular pressure than EXE group (37.94±18.34 vs 21.59±13.67 mmHg; P=0.03). CONCLUSION Eight-week aerobic training induced greater cardioprotection against ischemia reperfusion injury in rats compared to a single exercise session, due to an increased cardiac function. This suggests that exercise-induced cardioprotection is a multifactorial process that may involve different mediators according to the exercise duration.(AU)
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Animals , Male , Rats , Exercise , Myocardial Reperfusion Injury/chemically induced , Rats, WistarABSTRACT
Objective To observe myocardial tolerance to ischemia/reperfusion (I/R) injury in rats after exposure to X-ray irradiation.Methods Twelve male rats were randomly divided into control group and radiation group.The rat model of radiation-induced heart disease was established in the radiation group by precordial irradiation with 20.0 Gy of 6 MV X-ray in a single fraction.At 14 days after model establishment,the Langendorff perfusion technique was performed in the two groups and the cardiac parameters including left ventricular developing pressure (LVDP),left ventricular end diastolic pressure (LVEDP),maximal rate of left ventricular pressure rise/fall (+/-LVdp/dtmax),and coronary flow (CF)were recorded.Myocardial infarct size after I/R was compared between the two groups by 2,3,5-triphenyltetrazolium chloride staining.Results After 30 minutes of ischemia and 60 minutes of reperfusion,the irradiation group had a significantly slower CF than the control group (5.64±0.35 vs.8.38±0.52 ml/min,P=0.002).Moreover,the irradiation group had substantially poorer recovery of cardiac function in isolated hearts compared with the control group,as shown by a significantly reduced LVDP (25.4±2.31 vs.52.76±2.76 mm Hg(1 mm Hg=0.133 kPa),P=0.000),significantly reduced+/-LVdp/dtmax(547.04±78.74 vs.1 100.05±83.35 mm Hg(1 mm Hg=0.133 kPa)/s,P=0.001;-408.81±56.74 vs-813.62±73.82mm Hg(1 mm Hg =0.133 kPa)/s,P=0.002),and a significantly increased LVEDP (85.29±4.61 vs.65.65±3.65 mm Hg (1 mm Hg =0.133 kPa),P=0.012).X-ray irradiation induced a significantly increased percentage of myocardial infarct size in rats (44.67％±0.95％ vs.30.46％±0.96％,P=0.000).Conclusions X-ray irradiation can induce coronary injury,reduce myocardial tolerance to I/R injury,and increase myocardial infarct size after I/R in rats.
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Aim To investigate whether hydrogen sul-fide ( H2 S ) inhibits cardiomyocyte apoptosis induced by acute myocardial ischemia in isolated perfused rat heart. Methods The myocardial ischemia injury model was replicated with Langendorff isolated perfused rat heart, and the left anterior descending coronary ar-tery was ligated for 4 h. 40 male SD rats were divided into five groups randomly: sham group, ischemia group, and NaHS groups (5,10,20μmol·L-1). The segmental heart samples were used for HE staining. Cardiomyocyte apoptosis was detected with TUNEL as-say. The expressions of caspase-3 and Cyt-C in hearts were determined with Western blot analysis. Results Myocardial cells were found to show serious disorder and coagulated zonal necrosis under light microscope, the apoptotic rate of cardiomyocytes and the expression of caspase-3 and Cyt-C were significantly increased af-ter ischemia for 4h. Perfusion of NaHS resulted in more clear cell morphology and milder pathologic chan-ges of myocardiocytes according to the HE staining a-nalysis, and the significant decrease of expression of Cyt-C. After perfusion of 10,20 μmol·L-1 NaHS,the apoptotic rate of cardiomyocytes and the expression of caspase-3 were significantly decreased. Conclusion H2 S has certain protective effects on acute myocardial ischemic injury in isolated perfused rat heart via inhibi-ting cardiomyocyte apoptosis.
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Aims To observe the changes of endoge-nous hydrogen sulfide/cystathionine-γ-lyase (H2 S/CSE)system and to study the effects of H2 S on cardiac function,H2 S/CSE and myocardial infarct volumes in acute myocardial ischemic injury in isolated hearts of rats.Methods The myocardial ischemic injury model was established by the ligation of coronary artery.The hemodynamic parameters,such as the left ventricular developed pressure (LVDP),±dp/dtmax and coronary arterial flow(CF),were respectively recorded to evalu-ate the cardiac function.The content of H2 S and the activity of CSE in cardiac tissue were detected respec-tively at each time point after ischemia.Infarct vol-umes in isolated rat hearts were determined by dual staining with Evans-blue and TTC.Results (1 )Com-pared with those of the sham group,LVDP,±dp/dtmax and CF were significantly decreased at 30 min,1,2,3, 4 h after ischemia(P<0.01),there were no statistical-ly significant differences in the content of H2 S and the activity of CSE in cardiac tissue at 3 0 min after ische-mia.But during the periods from 1 h to 4h after ische-mia,the content of H2 S and the activity of CSE in car-diac tissue were significantly decreased,the infarct volumes were greatly increased compared with those of the sham control group (P<0.05 or P<0.01 ).(2) Compared with those of the ischemia 4h group,LVDP, ±dp/dtmax and CF were significantly increased in the NaHS low,middle and high dose groups (P<0.05 or P<0.01),the content of H2S and the activity of CSE in cardiac tissue were significantly increased in the NaHS low,middle and high dose groups(P<0.05 or P<0.01 ),and the infarct volumes were significantly decreased in NaHS middle and high dose groups(P<0.01 ).Conclusion H2S and CSE are involved in myocardial ischemic injury in isolated hearts of rats. Administration of NaHS could enhance the activity of CSE,increase the content of H2 S,and reduce infarct volumes.It could be suggested that H2 S has cardiopro-tective effects on acute myocardial ischemic injury.
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Eurycoma longifolia (E. longifolia) which is better known locally as Tongkat Ali is an indigenous plant in Malaysia. It belongs to the family of Simaroubaceae and is popular as a traditional medicine for its aphrodisiac properties. Throughout the years, several studies have been conducted to prove its effect on aphrodisiac action, antimalarial, antibacterial and anxiolytic properties but its effect to the cardiovascular system had not been fully explored. This study was aimed to demonstrate the changes that take place in the isolated heart following the injection of the extract. Methods: Three parameters that were measured included the coronary perfusion pressure (CPP), the left ventricular developed pressure (LVDP) and the heart rate (HR). Eighteen isolated rat hearts were used and were divided equally into three groups. The first group was to observe the effect of Isoprenaline, a β agonist while the second group was to see the effect of sodium nitroprusside (SNP), a nitric oxide (NO) donor. The dose which gave the maximum effect for these two positive controls was used to compare with the effect of E. longifolia water extract in the third group of rats. Isolated heart was mounted using the Langendorff apparatus and perfused with modified Krebs-Henseleit buffer. Doses of controls and the extract were instilled through an injection port, and the effect of each dose was monitored. Results: E. longifolia extract was found to reduce the CPP in normotensive rat at two of the highest doses. A dose of 1.0 mg of the extract reduced the CPP significantly from 34.52 ± 4.99 mmHg of the baseline value to 31.99 ± 4.93 mmHg while the dose of 10.0 mg of the extract reduced the CPP significantly to 32.67 ± 3.89 mmHg. However, there were no significant changes of effect of the extract on the LVDP and HR as compared to control. Conclusion: These early findings suggest that E. longifolia extract may have vasodilatory property, which supports its traditional usage with minimum cardiovascular side effects.
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Objective To explore the susceptibility differences of ventricular arrhythmia (VA ) in SHR rats with/without left ventricular hypertrophy(LVH) and the significance .Methods The experiments were performed on isolated hearts of 8‐week(the non‐LVH control group ,n=12) ,16 week‐old SHR(the LVH group ,n=12) and age‐matched Wistar Kyoto rats(Wistar ,the blank control group ,n=12) ,which were perfused in Langendorff mode with oxygenated Krebs‐Henseleit solution followed by a K+‐defi‐cient solution .The epicardial electrocardiogram was continuously monitored during all experiments .HE staining and collagen vol‐ume fraction(CVF)was used to evaluate the condition of LVH .Results Compared with the non‐LVH control group and the blank control group ,the low K+ induced ventricular arrhythmia occurred earlier with increased incidences and duration in the hearts of the LVH Group ,the incidences of ventricular tachycardia(VT) ,transient ventricular fibrillation(TVF) ,sustained ventricular fibrillation (SVF) and CVF were higher in the hearts of the LVH Group(P<0 .05) ,myocardial cell hypertrophy and myocardial cells intersti‐tial increased .Conclusion The ventricular arrhythmia occurred earlier with increased incidences and duration in the LVH tissue of SHR rats ,which implies that LVH is associated with VA .
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METHODS: Male Sprague Dawley rats which were used lor Langendoff isolated heart perfusion were divided into four groups; normal control group (n=6), 120 group (n=1), 130 group (n=8) and 140 group (n=8), these hearts were subjected to global ischemia for 20, 30 and 40 min respectively. Then coronary flow, heart rate, creatinine kinase and lactate dehydrogenase in effluent and the changes of cardiac function parameters were measured in different groups. Infarct and risk areas were measured by planimetry using Image/J software.
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Little is known about age-related differences in short-term effects of estradiol on ischemia-reperfusion (I/R) insults. The present study was designed to evaluate the effects of short-term treatment with estradiol on reperfusion arrhythmias in isolated hearts of 6-7-week-old and 12-14-month-old female rats. Wistar rats were sham-operated, ovariectomized and treated with vehicle or ovariectomized and treated with 17β-estradiol (E2; 5 µg·100 g-1·day-1) for 4 days. Hearts were perfused by the Langendorff technique. Reperfusion arrhythmias, i.e., ventricular tachycardia and/or ventricular fibrillation, were induced by 15 min of left coronary artery ligation and 30 min of reperfusion. The duration and incidence of I/R arrhythmias were significantly higher in young rats compared to middle-aged rats (arrhythmia severity index: 9.4 ± 1.0 vs 3.0 ± 0.3 arbitrary units, respectively, P < 0.05). In addition, middle-aged rats showed lower heart rate, systolic tension and coronary flow. Four-day E2 treatment caused an increase in uterine weight. Although E2 administration had no significant effect on the duration of I/R arrhythmias in middle-aged rats, it induced a marked reduction in the rhythm disturbances of young rats accompanied by a decrease in heart rate of isolated hearts. Also, this reduction was associated with an increase in QT interval. No significant changes were observed in the QT interval of middle-aged E2-treated rats. These data demonstrate that short-term estradiol treatment protects against I/R arrhythmias in hearts of young female rats. The anti-arrhythmogenic effect of estradiol might be related to a lengthening of the QT interval.
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Animals , Female , Arrhythmias, Cardiac/prevention & control , Estradiol/pharmacology , Myocardial Reperfusion Injury/physiopathology , Age Factors , Arrhythmias, Cardiac/physiopathology , Coronary Circulation/drug effects , Coronary Circulation/physiology , Electrocardiography , Estradiol/administration & dosage , Ovariectomy , Rats, Wistar , Ventricular Function, Left/drug effectsABSTRACT
Estudios clínicos y epidemiológicos sugieren que el danazol ha sido considerado como un factor de riesgo para desarrollar hipertensión. Para proporcionar información adicional acerca de este fenómeno, en este trabajo fue caracterizado el efecto inducido por el danazol y el hemisuccinato de danazol sobre la presión de perfusión y la resistencia vascular en corazón aislado de rata a flujo constante (modelo de Langendorff). Los resultados, mostraron que; 1) el hemisuccinato de danazol [10-9 M] incrementa la presión de perfusión en comparación con el danazol [10-9 M]; 2) los efectos del derivado de danazol [10-9 M - 10-4 M] sobre la presión de perfusión fueron inhibidos por flutamida [10-6 M]; 3) la nifedipina [10-6 M], bloqueó los efectos ejercidos por el hemisuccinato de danazol [10-9 M -10-4 M] sobre la presión de perfusión y 4) el efecto del derivado de danazol [10-9 M - 10-4 M] sobre la presión de perfusión en presencia del montelukast [10-6 M] fue inhibido significativamente (p=0,008). En conclusión, los efectos inducidos por el danazol y hemisuccinato de danazol sobre la presión de perfusión y la resistencia vascular podrían depender de su estructura química. Este fenómeno podría involucrar la interacción del receptor de andrógenos e indirectamente la activación de la síntesis de leucotrienos D4 (LTD4) y consecuentemente inducir variaciones en la presión de perfusión.
Epidemiological and clinical studies suggest that danazol has been considered a risk factor for hypertension development. In order to provide additional information about this phenomenon, the effect induced by both danazol and hemisuccinate of danazol on perfusion pressure and vascular resistance was characterized in isolated rat heart at constant flow (Langendorff model) and it was evaluated in this work.The results showed that; 1) hemisuccinate of danazol [10-9 M] increases perfusion pressure and vascular resistance in comparison with danazol [10-9 M]; 2) the effects of danazol-derivative [10-9 M - 10-4 M] on perfusion pressure were inhibited by flutamide [10-6 M]; 3) nifedipine [10-6 M] blockaded the effects exerted by hemisuccinate of danazol [10-9 M -10-4 M] on perfusion pressure; and 4) the effect of danazol-derivative [10-9 M - 10-4 M] on perfusion pressure in presence of montelukast [10-6 M] was significantly inhibited (p=0.008). In conclusion, the effects induced by both danazol and hemisuccinate of danazol on perfusion pressure and vascular resistance could depend on their chemical structure. This phenomenon could involve the interaction of androgene steroid-receptor and indirect activation of leukotriene D4 (LTD4) synthesis and consequently, induce variations in the perfusion pressure.
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Animals , Rats , Methylprednisolone Hemisuccinate/pharmacology , Danazol/adverse effects , Danazol/pharmacology , Vascular Resistance/drug effects , Coronary Vessels/drug effects , Danazol/analysis , Isolated Heart PreparationABSTRACT
BACKGROUND: Adenosine is secreted by myocardial cells during myocardial ischemia or hypoxia. It has many beneficial effects on arrhythmias, myocardial ischemia, and reperfusion ischemia. Although many investigators have demonstrated that cardioplegia that includes adenosine shows protective effects in myocardial ischemia or reperfusion injury, reports of the optimal dose of adenosine in cardioplegic solutions vary. We reported the results of beneficial effects of single dosage (0.75 mg/Kg/min) adenosine by use of self-made Langendorff system. But it is uncertain that dosage was optimal. The objective of this study is to determine the optimal dose of adenosine in cardioplegic solutions. MATERIAL AND METHOD: We used a self-made Langendorff system to evaluate the myocardial protective effect. Isolated rat hearts were subjected to 90 minutes of deep hypothermic arrest (15degree C) with modified St. Thomas' Hospital cardioplegia including adenosine. Myocardial adenosine levels were augmented during ischemia by providing exogenous adenosine in the cardioplegia. Three groups of hearts were studied: (1) group 1 (n=10) : adenosine -0.5 mg/Kg/min, (2) group 2 (n=10): adenosine -0.75 mg/Kg/min, (3) group 3 (n=10) : adenosine -1 mg/Kg/min. RESULT: Group 3 resulted in a significantly rapid arrest time of the heart beat (p<0.05) but significantly slow recovery time of the heart beat after reperfusion (p<0.05) compared to groups 1 and 2. Group 2 showed a better percentage of recovery (p<0.05) in systolic aortic pressure, aortic overflow volume, coronary flow volume, and cardiac output compared to groups 1 and 3. Group 1 showed a a better percentage of recovery (p<0.05) in the heart rate compared to the others. In biochemical study of drained reperfusates, CPK and lactic acid levels did not show significant differences in all of the groups. CONCLUSION: We concluded that group 2 [adenosine (0.75 mg/Kg/min) added to cardioplegia] has better recovery effects after reperfusion in myocardial ischemia and is the most appropriate dosage compared to group 1 and 3.
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Animals , Humans , Rats , Adenosine , Hypoxia , Arrhythmias, Cardiac , Arterial Pressure , Cardiac Output , Cardioplegic Solutions , Heart , Heart Arrest, Induced , Heart Rate , Ischemia , Lactic Acid , Myocardial Ischemia , Myocardial Reperfusion , Reperfusion , Reperfusion Injury , Research PersonnelABSTRACT
BACKGROUND: It has been reported that one or more intermittent reperfusion(s) during ischemia may be beneficial to the myocardium by washing out catabolites that have accumlated during ischemia. We evaluated the effect of four cycles of ichemia (2 minutes) and reperfusion (3 miutes), i.e., preconditioning on sustained ischemia (20 minutes) and reperfusion (60 minutes) using isolated Langendorff-perfused rabbit hearts. METHODS: After a fifty-minutes recovery phase, LVP , dLVP/dt and ECG were simultaneously recorded and ultrastructure of the stunned(or risk) area of the left ventricle was examined with conventional methods. RESULTS: In the preconditioned hearts, functional parameters such as LVPP(peak pressure), LVPP recovery rate and LVEDP(end-diastolic pressure) reached to 99.6+/-4.38mmHg, 98.0+/-4.67% and 14.0+/-2.90mmHg (109.3+/-2.91mmHg, 109.4+/-1.29mmHg and 10.7+/-2.67mmHg for the controls), respectively, after 30 minutes from the onset of reperfusion and maintained as in the controls(p>0.01). In contrast, in the ischemia-reperfusion hearts, LVPP and LVPP recovery rate were significantly reduced(81.6+/-6.83mmHg and 85.7+/-5.30%;p<0.05) and LVEDP elevated(21.2+/-3.00mmHg) but dP/dtmax, heart rate and ECG patterns were not significantly different between the preconditioned and the ischemia-refusion hearts during reperfusion. Furthermore, irreversible myocardial injury was homogeneous(both subendo- and subepicardial) in the ischmia-reperfusion hearts but only focal(subendocardial) in preconditioned hearts. CONCLUSION: These results suggest that preconditioning induced by very short periods of ischemia and reperfusion may enhance recovery of the left ventricular function and delay ultrastructhral changes to a certain extent during reperfusion.
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Electrocardiography , Heart Rate , Heart Ventricles , Heart , Ischemia , Myocardium , Reperfusion , Ventricular Function, LeftABSTRACT
Using method of orthogonal design we observed that low K+,high Ca2+ & low Mg2+ in perfusate produced the peak incidence of reperf-usion-indaced ventricular fibrillation & introduction of K+ & Ca2+ significantly affected the incidence & pnset of it, The appropriate prop-ortion of K+, ea2+ & Mg2+ in perfusate is the important effecting factor of reperfusion-induced arrhythmias in Langendorff heart of rats.
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Aim To introduce an improved method of Langendorff perfusion of the isolated rat heart that is easy to determine the termination of digestion.Methods Hearts were excised quickly from anesthetized SD rats.After the perfusate was free of blood,the solution was changed to perfusion buffer(0.6% Collagenase B,0.6% BSA,30 ?mol?L-1 Ca2+ in Tyrode solution)at 37℃.Hearts were isolated by traditional and improved Langendorff perfusion.Individual myocardial cell was measured by video-based motion edge-detection system(IonOptix,USA).Results One group of heart was digested by traditional Langendorff perfusion for 13~16 min.The termination of digestion could not be judged properly by this method.The nature and quality of the cardiocytes were various.The cardiocytes could not keep their survival and viability when exposed to Tyrode Solution with 1.8 mmol?L-1 Ca2+.Another group was digested by improved Langendorff perfusion.More than 80% survival cardiac ventricle myocytes could be obtained by improved Langendorff perfusion.Moreover,about 50% cardiac myocytes exposed to Tyrode solution with 1.8 mmol?L-1 Ca2+ could retain rod-shaped and be used to contraction research.The contraction of cardiocyte was stabile within 1 000 s.Conclusion Cardiac myocytes disassociated from improved Langendorff perfusion can be used in these studies of detecting contraction and relaxation.This method is economical and easy to control.The beginners are able to acquire the technological method over a short-term practice.