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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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【Objective】 To explore the protective effects of hemoglobin base on oxygen carries (HBOCs) with different oxygen affinity on isolated rat hearts. 【Methods】 Using Langendorff isolated heart perfusion model, 45 adult male SD rats (SPF grade), perfused with 30 min KH solution baseline, were randomly divided into sham operation group and control group: St. Thomas (STS) solution perfusion volume was 3mL/100g body weight; high P50 HBOCs group: [STS + high P50 HBOCs (P50=35.0 mmHg, 2.5 mg/100 g) product] perfusion volume was 3mL/100g body weight; medium P50 HBOCs group: [STS + medium P50HBOCs (P50=26.5.0 mmHg, 2.5 mg/100 g) product] perfusion volume was 3 mL/100 g body weight; low P50 HBOCs group: [STS + low P50 HBOCs (P50=11.0 mmHg, 2.5 mg/100 g) product] perfusion volume was 3mL/100g body weight, and the heart was arrested and placed in a 37℃ water bath to make the heart ischemic for 35 minutes, and then reperfused for 2 hours. The left ventricular development pressure (LVDevP), left ventricular end diastolic pressure (LVEDP), the rate of change of left ventricular pressure (LVPCR) and heart rate (HR) in the rat heart during reperfusion were observed and recorded. 1 min perfusion fluid from each rat in the basic and reperfusion phase was taken, and blood gas analyzer was used to measure the blood gas indexes of rats, and the myocardial injury marker enzymes [cardiac enzyme creatine kinase (CK-MB), lactate dehydrogenase (LDH) and the release of α-hydroxybutyrate dehydrogenase (α-HBDH)] were measured by ELISA kit. 【Results】 The cardiac function and the release of myocardial enzymes in the 5 groups of rats in the basal cardiac perfusion stage were similar (P>0.05). However, in the reperfusion stage, except for the insignificant changes in HR (P>0.05), the heart LVDevP (mmHg) of the three P50 HBOCs groups and the control group were 10.69±3.65 vs 8.50±2.88, 23.26 ±5.62 vs 8.50±2.88, 35.60±3.82 vs 8.50±2.88, LVEDP (mmHg) were 43.34±8.08 vs 54.64±7.42, 39.43±8.30 vs 54.64±7.42, 31.46±4.11 vs 54.64±7.42, dp/dt were 12.09±9.96 vs 6.09±0.98, 25.65±8.87 vs 6.08±0.98, 35.32±9.33 vs 6.09±0.98, -dp/dt were 17.53±11.28 vs 11.39±2.16, 28.80±13.70 vs 11.39±2.16, 43.36±3.83 vs 11.39±2.16, respectively (all P<0.05); the rebound situation and the release of CK-MB, LDH, and α-HBDH in the three P50 HBOCs groups were better than those in the control group (P<0.05). Among the three P50HBOCs products, the low P50HBOCs group had the best cardiac function indexes. The myocardial enzyme indexes of the high, medium and low HBOCs groups were CK-MB (ng/mL): 110.47±4.04, 90.2±2.46, 77.1±3.51; LDH (U/L): 162.23±7.71, 135.13±23.69, 92.20±4.21; a-HBDH (U/L): 228.00±8.03, 172.30±8.99, 131.00±2.02. 【Conclusion】 STS solution containing HBOCs products can improve the function of the reperfused heart at normal temperature ischemia for 35 min and 2 h reperfusion, and reduce heart damage. The STS solution containing low P50 HBOCs has the most obvious protective effect in rat isolated heart perfusion.
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Objective To observe the protective effect of Xinmailong injection ( XML ) on myocardial ischemia reperfusion (I/R) injury in rats model. Methods The levels of SPF 60 successful acute myocardial ischemia rat models were randomly divided into control group, I/R group and XML group( Different drug concentrations 50 mg/L, 100 mg/L, 200 mg/L, 400 mg/L). The control group was continuously given K-H nutrient solution for 2 hours, the other group was given respective different drug concentrations or K-H nutrient solution by Langendorff isolated heart perfusion method after ischemia 30 minutes. The following indicators were detected: Hemodynamics included heart rate (HR), left ventricular development pressure (LVDP) and ±dp/dtmax; the myocardial enzymes included creatine kinase (CK), creatine minase- MB (CK-MB), troponin-1 (Tn-I) and myoglobin (MYO), coronary flow and myocardial infarct size were observed. The expression of Bax and Bcl-2 in each group was detected by Western blotting and immunofluorescence. Results Xinmailong injection could alleviate LVDP and ±dp/dtmax; decrease the release of CK, CK-MB, Tn-I, MYO and the shrink area of myocardial infarction; increase the coronary flow; enhance heart rate fast and certain inhibition of myocardial apoptosis. Conclusion Xinmailong injection can alleviate the damage of cardiac function caused by myocardial ischemia/reperfusion injury.
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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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OBJECTIVES@#To investigate the effect of taurine magnesium coordination compound (TMCC) on torsades de pointes (TdP) in isolated guinea pig hearts.@*METHODS@#Healthy male guinea pigs weighting 250~300 g were randomly divided into 4 groups:①TdP model group (=7):Isolated hearts were perfused by normal K-H solution 20 minutes, then perfused by slowly activated delayed rectifier potassium current(IKs) blocker 10mol/L Chromanol 293B under hypokalemic solution(1.8 mmol/L) to establish TdP model;②~④ TdP model + TMCC group (=6):Isolated hearts were perfused by normal K-H solution for 20 minutes, then perfused by IKs blocker 10mol/L Chromanol 293B under hypokalemic solution(1.8 mmol/L) for 60 minutes, at the same time TMCC which concentration was 1, 2, 4 mmol/L was administered respectively by Langendorff retrograde aortic perfusion method. Cardiac surface electrocardiogram of guinea pigs was collected and recorded by Biopac electrophysiological recorder. Incidence of TdP, transmural dispersion of repolarization (TDR), instability of QT interval were acquired from Lead Ⅱ electrocardiograph (ECG) wave forms to describe the effect of TMCC on TdP model. Datas were acquired at the time of 20 min and pre-TdP, in case there was no TdP observed, a value of 60 min was entered for calculation purpose.@*RESULTS@#Incidence of TdP in TdP model group was 6/7. TdP incidence could be decreased significantly by 1, 2, 4 mmol/L TMCC, and was 5/6, 1/6, 0/6 respectively. Compared with the pre-drug, Chromanol 293B under hypokalemic solution in TdP model group increased TDR(corrected) evidently(0.05). Compared with the TdP model group, 2, 4 mmol/L TMCC could evidently decrease the instability of QT interval induced by Chromanol 293B under hypokalemic solution(<0.05). During the establishment of TdP model, P waves in more than one cardiac cycle continuously were disappeared in ECG. However, P wave could always be seen independent in ECG acquired from TdP model + TMCC group.@*CONCLUSIONS@#TMCC can play the role against TdP through decreasing TDR and instability of QT interval, and inhibiting early after depolarization(EAD).
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Animals , Male , Anti-Arrhythmia Agents , Pharmacology , Electrocardiography , Guinea Pigs , In Vitro Techniques , Long QT Syndrome , Magnesium , Pharmacology , Random Allocation , Taurine , Pharmacology , Torsades de Pointes , Drug TherapyABSTRACT
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 investigate the effect of Buyang-Huanwu decoction on left ventricular diastolic function in DHF rats.Methods Thirty male Sprague-Dawley rats were randomly divided into the normal group (n=10),the Chinese medicine group (n=6),the western medicine group (n=6) and the model group (n=6).Except for the normal group,the other groups got abdominal aorta stenosis.After 12 weeks,The Chinese medicine group was given Buyang-Huanwu decoction 12.72 g/(kg·d),and the western medicine group was given metoprolo 1 0.004 5 g/(kg·d),and the normal group and the model control group were given water.After once daily for 8 weeks,echocardiography was used to measure EF,E/A ratio and e/a ratio.The heart rate,left ventricular diastolic pressure,left ventricular end-diastolic pressure,tension and maximal change in pressure of left ventricular were measured by Langendorff.Results Compared with the model group,the e/a value (1.11 ± 0.28 vs.0.67 ± 0.20) of the Chinese medicine group significantly increased (P＜0.05),and the ventricular muscle tension (0.86 ± 0.64 g vs.1.01 ± 0.33 g) significantly decreased (P＜0.05).Conclusions Buyang-Huanwu decoction could improve cardiac relaxation by reducing ventricular muscle tension,thus improving diastolic function of diastolic heart failure rats.
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AIM:To observe the time pattern of intrinsic myocardial dysfunction and other organ dysfunction in a rat model of mild cecal ligation and puncture (CLP).METHODS:Male SD rats were randomly divided into sham group and CLP group.At 6 h, 9 h and 12 h after sham operation or CLP, intrinsic myocardial systolic and diastolic functions were determined by Langendorff system.The expression of cardiac tumor necrosis factor (TNF)-α, intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) was measured.In addition, serum activity of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) as well as blood urea nitrogen (BUN) were analyzed.For evaluating pulmonary edema, the lung wet-dry weight (W/D) ratio was calculated.RESULTS:In mild CLP rats, the mortality rate was 26.7% on day 10 after CLP.At 9 h and 12 h after CLP, the maximum rate of positive and negative changes in left ventricular pressure (±dp/dt) were decreased in CLP group compared with sham group.At 6 h after CLP, cardiac mRNA expression of TNF-α, ICAM-1 and VCAM-1 was increased in septic rats compared with the controls.At 9 h after CLP, cardiac protein levels of TNF-α and VCAM-1 were higher in CLP group than that in sham group (P<0.05).The serum AST activity at 9 h and ALT activity at 12 h after CLP were increased in CLP group compared with sham group.However, no difference in BUN and lung W/D ratio at 6 h, 9 h and 12 h between CLP group and sham group was observed.CONCLUSION:Our findings highlight the presence of intrinsic myocardial dysfunction at 9 h after CLP in a rat model of mild CLP.Intrinsic myocardial dysfunction occurs earlier than the liver and kidney dysfunctions.
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Objective To investigate the effect of dexmedetomidine on myocardial repolarization heterogeneity and the expression of Cx43 during ischemia-reperfusion and the role of Cx43 in the dexmedetomidine for inhibition of myocardial repolarization heterogeneity during ischemia-reperfusion in isolated rabbit hearts.Methods Eighteen healthy adult rabbits,weighing (2.0±0.5) kg,were randomly divided into three groups after Langendorff isolated heart perfusion model had been prepared and K-H fluid had been perfused and balanced 15 min.In the control group (group C),37℃ K-H fluid was continuously perfused and balanced for 150 min.In group IR,K-H fluid was stopped after perfusion continue filling for 15 min,and then made the cardiac stop for 60 min with the injection of Thomas solution 10 ml/kg while the heart was protected by the 4℃ Thomas solution around.Following the reperfusion of 4℃ Thomas solution 5 ml/kg was performed for 30 min and the heart was resuscitated by the perfusion of K-H fluid for 60 min.In dexmedetomidine group given (group DEX),dexmedetomidine was added in the K-H fluid and the Thomas solution 25 ng/ml.The other procedures were the same as those of group IR.The heart rate (HR),90% monophasic action potential duration (MAPD90) were recorded at the time of balance perfusion record 15 min (T0),continue perfusion 15 min/balance 30 min (T1),reperfusion 30 min/balance 120 min (T2) and reperfusion 60min/balance 150 min (T3).The transmural dispersion of repolarization (TDR) was calculated.To observe the cardiac reperfusion arrhythmia and rebeating time and recording.Detection expression of Cx43 in the left ventricular myocardial by Western blot and immunohistochemistry at T3.Results Group DEX cardiac resuscitation time was significantly shorter than that of group IR (P<0.05).In group DEX.Compared with T0,HR was significantly decreased and TDR was significantly increased in groups IR and DEX at T2、T3 (P<0.05).Compared with group IR,the TDR of group DEX was significantly decreased at T2、T3 (P<0.05).Compared with group C,the expression of Cx43 was decreased (P<0.05) and the distribution was not uniform in groups IR and DEX.Compared with group IR,the expression of Cx43 was decreased (P<0.05) and the distribution was improved in group DEX.Conclusion Dexmedetomidine could inhibits myocardial repolarization heterogeneity of ischemia-reperfusion injury,and thus play a stable cardiac conduction,reduce reperfusion arrhythmias,and its mechanism may be that dexmedetomidine could inhibits gap junctional uncoupling and inhibits expression and distribution of connexins decreased.
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AIM:To study the effects of methylene blue (MB) on myocardial ischemia/reperfusion (I/R)-induced mitochondrial injury in isolated rat hearts.METHODS:Spragure-Dawley (SD) rats were divided into 3 groups randomly (n=6): control group, I/R model group and MB treatment group (IR+MB group).The isolated rat hearts were prepared and set up to Langendorff perfusion.The rats in I/R+MB group received MB (2 mg/kg) by intraperitoneal injection 2 h before operation.The hearts in control group were perfused with K-H solution for 110 min consecutively.The hearts in I/R group and I/R+MB group were in equilibrium for 20 min, following by 45 min of global ischemia, and then reperfused for 60 min.The heart rate (HR), left ventricular developed pressure (LVDP), left ventricular pressure maximum change rate (±dp/dtmax) and left ventricular end-diastolic pressure (LVEDP) were recorded.The perfusate was collected to determine the activity of creatine kinase-MB (CK-MB) and lactate dehydrogenase (LDH).The contents of reactive oxygen species (ROS), malondialdehyde (MDA) and adenosine triphosphate (ATP), and the activity of superoxide dismutase (SOD) in the myocardial tissues were all determined.Histopathological examination of left ventricle was performed.The mitochondria from the heart tissues was isolated and the mitochondrial swelling and mitochondrial membrane potential (MMP) were analyzed.RESULTS:Compared with control group, the hearts in I/R group showed poorer function, higher CK-MB and LDH levels in the perfusate, increased ROS and MDA contents, higher SOD activity and less ATP content in the heart tissues (P<0.05).Furthermore, the mitochondrial swelling level increased and MMP reduced in I/R group (P<0.05).Compared to I/R group, MB improved heart function and reduced the release of CK-MB and LDH (P<0.05).MB also decreased ROS and MDA contents, and increased the activity of SOD and the content of ATP (P<0.05).In addition, MB alleviated mitochondrial swelling and restored the reduced MMP (P<0.05).CONCLUSION: MB protects the isolated rat hearts from I/R-induced injury by attenuating the damage of mitochondria.
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Aim To investigate the protective effects of dihydroquercetin(DDQ) against myocardial ischemis reperfusion injury(MIRI) in rats.Methods Male Sprague-Dawley rats were randomly divided into 4 groups(n=10):normal,control,I/R model, and I/R model+DDQ(5,10 mg·L-1).This study used an isolated Langendorff rat heart model.The left ventricu-lar developed pressure(LVDP),heart rate(HR) and the maximum rise and fall rate of the left ventricular pressure(±dp/dtmax) were monitored and documented using a physiological recorder.The levels of lactate dehydrogenase(LDH) and creatine kinase(CK) were analyzed using enzyme-linked immunosorbent assay(ELISA).Infarct size was measured using 2,3,5-triphenyltetrazolium chloride staining.The levels of superoxide dismutase(SOD) and malondialdehyde(MDA), as well as the ratio of glutathione/glutathione disulfide(GSH/GSSG) were measured via ELISA.HE staining was used to observe the pathological changes of myocardial tissue.Results Compared with the I/R model group, the I/R model+DDQ groups raised hemodynamic parameters, SOD level, and GSH/GSSG ratio;and reduced the amount of CK, LDH, MDA levels.Moreover, the I/R model+DDQ groups had lower infarct size and pathological changes in myocardial tissue than I/R model group.Conclusion DDQ exertes cardioprotective effects against I/R via improving the oxygen free radical scavenging ability, the inhibition of oxygen free radical and reducing lipid peroxidation.
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@#In this study, normal isolated rat heart model was adopted to investigate the inotropic and electrocardiac effect of AF-HF001 with Lanfendorff technique on the left ventricular systolic pressure(LVSP), left ventricular end diastolic pressure(LVEDP), peak rate of rise of left ventricular pressure(+dp/dtmax)and peak rate of fall of left ventricular pressure(-dp/dtmax). The results indicated that AF-HF001 could significantly enhance LVSP, LVEDP and ±dp/dtmax in a dose-dependent manner and exerted a positive inotropic effect on normal isolated rat hearts. This study also analyzed the electrocardiac effect of AF-HF001 with the electrodes located on tip of heart, ventricular free wall and aortic root. The results exhibited that AF-HF001 did not change PR, QRS, QT or HR at various concentrations, which means that AF-HF001 could safely increase cardiac contractility. This research lays a good foundation for the further study on AF-HF001 and research on structure-activity relationship of its analogs.
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OBJECTIVE:To study the improvement effects of baicalein against myocardial ischemia/reperfusion(I/R)injury in rats. METHODS:I/R injury model was induced by Langendorff method. Isolated heart of 40 rats were randomly divided into nor-mal group(continuous perfusion),model group(perfusion withdrawal 20 min)and baicalein high,medium and low concentration groups (K-H solution of baicalein 40,10 and 2.5 μmol/ml 10 min before perfusion withdrawal). The myocardial infarction rate, the activity of creatine kinase(CK)and lactate dehydrogenase(LDH)in coronary effluent liquid,SOD activity and MDA content, GSH/GSSG and apoptosis rate of cardiac muscle cell in myocardial tissue were detected. RESULTS:Compared with normal group, the myocardial infarction rate,apoptosis rate of cardiac muscle cell,the activities of CK and LDH and the content of MDA in myo-cardial tissue were increased in model group,while SOD activity and GSH/GSSG of myocardial tissue decreased(P0.05). CONCLUSIONS:Baicalein has cer-tain improvement effect on myocardial I/R injury in rats,and its mechanism may be associated with antioxidant and anti-apoptosis effect of baicalein.
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Objective To study the effects of dexmedetomidine on the monophasic action po-tential duration and the transmural dispersion of repolarization during ischemia-reperfusion of isolated rabbit hearts and thus explore its effect on myocardial ischemia-reperfusion electrophysiological char-acteristics.Methods Eighteen healthy adult rabbits,weighing (2.0±0.5)kg,were randomly divided into 3 groups after successful preparation of Langendorff isolated heart perfusion model and 1 5 min perfusion and balance of K-H fluid.In the control group (group C),37 ℃ K-H fluid was continuously perfused and balanced for 1 50 min.In the ischemia/reperfusion group (group IR),K-H fluid was stopped after continuous perfusion and balance for 1 5 min and cardiac arrest was induced for 60 min with the injection of Thomas solution (4 ℃,10 ml/kg)while the heart was protected by the low tem-perature Thomas solution (4 ℃)around it.Reperfusion of Thomas solution (4 ℃,5 ml/kg)was performed for 30 min and the heart was resuscitated by the perfusion of K-H fluid for 60 min.In dexmedetomidine group (group DEX),dexmedetomidine (25 ng/ml)was added in the K-H fluid and the Thomas solution.Other procedures were same as in group IR.Heart rate(HR),monophasic ac-tion potential amplitude (MAPA)of the three layers of heart [endocardium (Endo),myocardium (Mid)and epicardium (Epi)],0 phase maximal increase rate (Vmax),90% monophasic action po-tential duration (MAPD90 )and transmural dispersion of repolarization (TDR)were recorded at the time of continuous balance perfusion 1 5 min(T0 ),continuous perfusion 1 5 min/balance 30 min(T1 ), reperfusion 30 min/balance 120 min(T2 )and reperfusion 60 min/balance 1 50 min(T3 ).Cardiac ar-rhythmia and resuscitation time at cardiac reperfusion were observed,without using drugs to restore normal cardiac rhythm.Results In group DEX,cardiac resuscitation time was significantly shorter (1 6.67±3.78)s than that in group IR (46.33±7.29)s (P <0.05);At T2 ,in group IR,arrhythmia was seen in 6 rabbits and normal cardiac rhythm was restored within 2 min in two rabbits,while in group DEX,arrhythmia was seen in 2 rabbits and normal cardiac rhythm was restored within 2 min in one rabbit,without the use of any drugs.When compared with T0 ,HR was slower at T2 and T3 in group IR and at T1-T3 in group DEX (P <0.05);Compared with T1 ,HR was slower at T2 and T3 in group DEX (P <0.05);Compared with T2 and group C,HR was slower at T3 in group DEX;At T1-T3 ,HR in group DEX were significantly slower than that in group IR (P <0.05).Compared with T0 ,MAPD90 of Mid at T1 and Epi,Mid,Endo at T2 and T3 in group DEX were significantly extend-ed (P <0.05);Compared with T1 ,MAPD90 of Epi,Mid,Endo in group DEX were significantly ex-tended at T3 ;MAPD90 of Mid in group DEX was significantly longer than that in group C at T3 (P <0.05);At T2 and T3 ,MAPD90 of Epi,Mid,Endo in group DEX were longer than that in group IR (P <0.05).Compared with T0 and group C,TDR at T2 and T3 in group IR and at T1-T3 in group DEX significantly increased (P <0.05),while TDR in group DEX were less than that in group IR at T2 and T3 (P <0.05).Conclusion Dexmedetomidine appeared to prolong MAPD and restrain the dis-proportion of resuscitation of myocardial ischemia-reperfusion injury.Dexmedetomidine could have the effect of stabilizing myocardial ischemia-reperfusion electrophysiological characteristics.
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Objective Heart transplantation is an effective treatment of end-stage heart diseases and extending the time of donor heart preservation helps to make up for the shortage of donor hearts. This study was to investigate whether high-pressured mixed gas ( HPMG) of carbon monoxide and oxygen could prolong the time of donor heart preservation and its mechanisms. Methods Forty-eight C57BL/6 male mice aged 4-6 weeks were randomly divided in-to four groups of equal number:control ( the donor heart isolated but not transplanted) , immediate transplantation ( the donor heart transplanted right after isolated) , HTK-preservation ( the donor heart preserved in histidine-tryptophan-ketoglutarate solution for 24 hours after isolated, and HPMG preservation ( the donor heart preserved in an HPMG chamber with the oxygen partial pressure of 3200 hPa and carbon monoxide partial pressure of 800 hPa for 24 hours after isolated) .Another 36 recipient mice aged 6-8 weeks were randomly assigned to receive the donor heart immediately after harvested (n=12), preserved in HTK solution (n=12), or preserved in HPMG (n=12).At 2 hours after transplantation, the status of heart re-beating and cardiac function were compared among different groups of recipient mice.At 24 hours, tissues were taken from the transplanted hearts for examination of pathologic changes by HE stai-ning, detection of the apoptosis of cardiac cells by TUNEL, and determination of the expressions of microtubule-associated protein 1 light chain 3 -Ⅱ(LC3-Ⅱ) and B cell lymphoma/leukemia-2 (Bcl-2) by Western blot. Resul ts The re-beating rates of the imme-diately transplanted and HPMG-preserved hearts were significantly higher than that of the HTK-preserved ones (P<0.05).At 2 hours after transplantation, the cardiac function scores were 2.5 (2.0-2.9), 0.8 (0.5-1.0), and 4.5 (4.0-4.5) in the immediate implantation, HPMG-preservation and HTK-preservation groups respectively, with statistically significant differences between any two groups (P<0.05).The expressions of LC3-Ⅱand Bcl-2 were 2.06 ±0.29 and 0.87 ±0.18 in the HPMG-preserved heart recipients and 1.24 ±0.20 and 2.07 ±0.32 in the immediately transplanted heart recipients, both higher than 0.13 ±0.03 and 0.19 ±0.02 in the controls and 0.16 ±0.06 and 0.26 ±0.08 in the HTK-preserved heart recipients (P<0.05), the Bcl-2 higher in the HTK-pre-served heart recipients than in the controls (P<0.05), and the LC3-Ⅱ expression higher in the HPMG-preserved heart recipients than in the immediately transplanted heart recipients (P<0.05).HE staining showed that cell edema and inflammatory cell infiltration were more obvious in the HPMG-preserved heart recipients than in the controls and immediately transplanted heart recipients but less obvious than in the HTK-preserved heart recipients.The rate of cell apoptosis was dramatically increased in the HPMG-and HTK-pre-served heart recipients ([5.04 ±1.77]%and [26.72 ±5.23]%) in comparison with the controls ([1.08 ±0.56]%) (P<0.01) and immediately transplanted heart recipients ([2.13 ±1.71]%) (P<0.01) but decreased in the HPMG as compared with the HTK-preserved heart recipients (P<0.01). Conclusion High-pressured mixed gas preservation can reduce cold ischemia-reperfu-sion injury of the donor heart, which may be associated with its promotion of autophagy, provision of energy to cells, and apoptosis of cardiocytes in the donor heart.
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Objective: To explore the relationship between expression of tumor necrosis factor-α( TNF-α) and electrophysiological heterogeneity in isolated heart tissues and isolated rat ventricular myocytes.The arrhythmogenic mechanisms of TNF-αwere further studied.Methods:Langendorff perfused heart tissues models were used to verify the arrhythmogenic effects of TNF-α.The monophasic action potentials( MAPs) of the endocardium and epicardium from the isolated heart tissues were recorded by elec-trophysiological experiments.The isolated rat ventricular myocytes were obtained by enzymatic dissociation.K+currents(Ito,IK1)were recorded by using whole cell patch clamp technique.Results: Compared to the control group, the difference in MAPD between endocardium and epicardium dramatically increased with TNF-α( P<0.05 ) .TNF-αcould cause MAP duration ( MAPD ) prolongation, and a single dose of TNF-αdifferentially affected the MAPs of endocardium and epicardium of isolated heart tissues.Compared to the control group,the K+currents(Ito,IK1)were dose-dependently decreased with TNF-αin rat ventricular myocytes(P<0.05).However, etanercept had no effects on the MAPD in the absence of TNF-α.Conclusion:TNF-α-induced heterogeneity of MAPD between the endo-cardium and epicardium may provide the substrate for the onset of ventricular arrhythmias during acute myocardial infarction.The effect might be associated with TNF-αcontribute to re-entrant ventricular arrhythmias which resulted from decreased K+currents(Ito,IK1).
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Background: Decaying stem juice of Musa acuminata × balbisiana is commonly used by local communities and traditional herbalist in Central Uganda in the management of cardiovascular conditions like hypertension. Aims: The study investigated the ionotropic and chronotropic effect of fresh and decaying stem juice of Musa acuminata × balbisiana on the isolated perfused rabbit heart. Materials and Methods: Methods. Study Design: An experimental study. Place and Duration of Study: Study was done at the Dept of Pharmacology & Therapeutics Pharmacology Lab between December 2012 to March 2013. Experimental Procedure: An experimental study determined the effects of fresh and decayed stem juices of Musa acuminate X balbisiana on the rate and force of contraction of an isolated rabbit heart using Langendorff’s heart perfusion experiment and methods. The heart rate (beats/minute) was determined. The force of contraction of the heart was determined by measuring the height of each peak on the kymogram. Results: The force and rate of contractility of an isolated perfused rabbit decreased with increasing doses of the stem juice from 0.156 mg/mL to 100mg/mL for both the fresh and decayed stem juice of M. acuminata. The decrease could be associated with the high [K+] ions that decrease the membrane potential or cause hyperpolarization the myocardial cell membranes leading to reduced force and rate of heart contractility. The effect of the fresh stem juice was short lived and at very high concentrations, it caused a cardiac arrest while the effect of the decayed stem juice was prolonged. Conclusion: Fresh and decayed stem juice of Musa acuminata × balbisiana have compounds that cause a negative ionotropic and chronotropic effect on an isolated perfused rabbit heart.
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Aim To study the mechanisms of inotropic responses to doxazosin enantiomers in the isolated rat atrium.Methods We analyzed the positive inotropic response to (-)doxazosin and the negative inotropic response to (+)doxazosin in the left atrium of rat u-sing receptor-pharmacological technique.Results In the preparation treated with verapamil,the positive in-otropic responses to 3 μmol·L-1 (-)doxazosin were significantly inhibited from the control level (245.7 1 ± 44.29)mg to (172.50 ±43.34)mg,(P<0.05).In the preparation treated with methylene blue,the posi-tive inotropic responses to 3 μmol·L-1 (-)doxazosin were significantly potentiated from the control level (245.7 1 ±44.29 )mg to (303.33 ±45 .90 )mg,(P<0.05 ).In the preparation treated with H-89 ,the positive inotropic responses to 3,10 and 30 μmol · L-1 (-)doxazosin were (338.57 ±96.86 ) mg, (471.43 ±107.61)mg and (520.00 ±103.44)mg, which were significantly (P<0.05 ~0.01)larger than the control levels of (245.71 ±44.29)mg,(314.29 ±90.34)mg and (357.14 ±68.49 )mg.Treatment with phenoxybenzamine,atropine,propranolol or indo-methacin did not significantly affect the responses to doxazosin enantiomers.Conclusion The positive ino-tropic responses to (-)doxazosin in the isolated left a-trium of rat are partially involved in L-type Ca2+chan-nels and intracellular cGMP level.However,α-adre-noceptors,muscarinic receptors,β-adrenoceptors and cyclooxygenases are not related to the responses to doxazosin enantiomers.
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Objective To investigate the protective effects and mechanism of TG 6 on myocardial ischemia/reperfusion injury . Methods the protective effects of TG 6 on myocardial ischemia/reperfusion was investigated by setting up models of ischemia and reperfusion of rats induced by ligating the left coronary anterior descending artery in vivo,isolated rat hearts through an improved Lange-ndorff device, and hypoxia /reoxygenation injury of neonatal rat cardiomyocytes , and the serum CK,LDH,T-SOD, MDA were taken as research markers .Results TG6 significantly reduced the myocardial infarct size , decreased the activity of CK and the content of MDA in serum, reduced the activity of LDH, and increased the activity of T-SOD in vivo;TG6 obviously increased the coronary blood flow after low rate perfusion and reperfusion , decreased the content of MDA and the leakage of CK , LDH in myocardial tissue , elevated the activity of T-SOD in vitro of isolated rat hearts;TG6 had no effects on cells in normal growth condition , raised the viability of cardio-myocytes significantly, and reduced the rate of CK leakage and the content of [Ca2+]i obviously in Na2S2O4 treated cells in vitro of neonatal rat cardiomyocytes .Conclusion TG6 could effectively protect myocardial ischemia/reperfusion injury .
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We studied the effects of cotinine, the major metabolite of nicotine, on nicotine-induced decrease in prostacyclin (PGI2) synthase activity of microsomes from isolated rabbit heart after sympathetic stimulation. Rabbit hearts were isolated along with their sympathetic nerves and perfused in accordance to the Langendorff method. Hearts were randomly divided into 10 groups treated with cotinine, either during sympathetic stimulation or prior to nicotine administration. PGI2 formation in cardiac microsomes was assessed by radioimmunoassay. The results showed that sympathetic stimulation increased PGI2 synthase activity of heart microsomes by 32 %. Nicotine dose dependently decreased PGI2 while cotinine increased it. In addition, perfused before nicotine, cotinine prevented the PGI2 decreasing effect of nicotine. The results suggest that pre-treatment with cotinine can be involved in the modulation of nicotine effects on PGI2 in hearts subjected to sympathetic stimulation.