钙通道阻滞剂MN9202对家兔血流动力学的影响

目的观察新的二氢吡啶类钙拮抗剂2,6二甲基1,4（3硝基苯基）1,4二氢3,5吡啶二羧酸3甲酯5正戊酯（MN9202）对家兔血流动力学的影响。方法家兔经乌拉坦氯醛糖混合麻药麻醉,进行左心室、股动脉和下腔静脉插管,同时开胸用电磁流量计测定主动脉根部血流量作为心排出量指标。采用计算机联机实时分析方法,观察MN9202的血流动力学效应。结果间隔10min,按累积剂量方法分别静脉注射MN92021、5、10μg/kg,随着给药剂量的增加,动物的血压、总外周阻力显著下降,与此同时,心排出量（CO）显著增加,心脏泵血功能改善,具有明显的剂量依赖关系。结论MN9202具有显著的的血流动力学效应,不仅作用强,而且持续时间长。     

MN9202降压作用的实验研究

目的 :探讨 2 ,6 -二甲基 - 4- （3-硝基苯基 ） - 1,4-二氢 - 3,5 -吡啶二羧酸 - 3-甲酯 - 5 -正戊酯 （MN92 0 2 ）的降压作用及其机制。方法 :应用清醒大鼠及肾性高血压大鼠 ,观察 MN92 0 2的降压作用 ,并采用离体兔胸主动脉张力实验观察 MN92 0 2的扩血管作用。结果 :腹腔注射 MN92 0 2 10 ,30 ,10 0 μg/ kg对正常动物和肾性高血压大鼠均可产生明显的降压作用 ,具有明显的剂量依赖关系。MN92 0 2和 Nitrendipine对抗 KCl引起家兔主动脉收缩的 IC50 分别为2 .1μmol/ L 和 3.1μmol/ L,Emax则为 6 8.8%和 5 4.9%;对抗 NE引起收缩的 IC50 分别是 2 .0 μm ol/ L 和 2 .2 μmol/L ,Emax是 34 .6 %和 32 .2 %;其作用不受内皮的影响 ;MN 92 0 2可显著抑制 NE的依赖细胞外 Ca2 +收缩反应 ,而对内 Ca2 +收缩反应则无明显抑制作用。结论 :MN92 0 2具有明显的扩血管效应 ,其作用与其抑制电压依赖性钙通道 ,减少 Ca2 +内流有关。     

缬沙坦对心力衰竭心肌细胞收缩功能和钙瞬变的影响

目的:探讨缬沙坦对心力衰竭(HF)大鼠心肌细胞收缩功能和钙瞬变的作用。方法:结扎大鼠冠状动脉左前降支8周后,复制充血性HF模型,随机分为2组,即缬沙坦治疗组与HF对照组,分别用缬沙坦和安慰剂治疗,另设假手术组。治疗12周后,用急性酶解法获得单个大鼠心室肌细胞,用共聚焦显微镜测定单个细胞的收缩功能和钙瞬变。结果:①HF对照组左室舒张末压(LVEDP)明显大于假手术组(P<0.01),左室最大收缩压(LVSP)血压和左室内压的最大上升/下降速率(±dp/dtmax)明显小于假手术组(P<0.05、P<0.05和P<0.01);而缬沙坦治疗组LVSP和±dp/dtmax明显高于HF对照组(P<0.05和P<0.01),LVEDP明显小于HF对照组(P<0.01)。②HF对照组的心肌细胞表面积和最大舒张长度均大于假手术组(P<0.01),缩短分数明显低于假手术组(P<0.05),经缬沙坦治疗后均有明显改善(P<0.01)。③HF对照组心肌细胞的钙瞬变明显低于假手术组(P<0.01),舒张末期钙浓度明显升高(P<0.05),钙浓度下降时间明显减慢(P<0.01),经缬沙坦治疗后均明显改善(P<0.01)。结论:缬沙坦治疗能明显改善充血性HF的心肌细胞收缩功能,可能与改善HF心肌细胞钙调控异常有关。     

不同周龄大鼠心肌细胞收缩/舒张功能的研究

目的研究不同周龄对大鼠心肌细胞收缩/舒张功能的影响。方法SD大鼠分为三个周龄组:A组(12~15周)、B组(36~41周)和C组(51~55周),并以常规酶解法分离成年大鼠心肌细胞,观察分离即刻(D时间点)、复钙1h后(E时间点)和电刺激10min后(F时间点)心肌细胞成活率,采用IonOptix单细胞动缘探测系统同步检测心肌细胞的收缩幅度、收缩/舒张速度和钙瞬变等,这些指标均由计算机自动实时采集并记录。结果复钙1h后和电刺激10min后心肌细胞成活率降低均有统计学意义(P<0.05或P<0.01),周龄越大越明显,随着周龄的增大,心肌细胞收缩幅度(峰值高度,ph)、心肌细胞收缩幅度/单个心肌细胞的长度百分比(ph/bl%)、最大收缩速率(maxi mal velocity of contraction, dL/dt)、最大舒张速率(maxi mal velocity of relaxation,-dL/dt)和钙瞬变幅度(FFI)降低,ph在A组、B组和C组分别为(0.14±0.06),(0.12±0.05),(0.11±0.05)μm;ph/bl%分别为(9.17±3.54)%、(7.14±2.58)%和(6.56±2.36)%; dL/dt分别为(2.01±0.74),(1.82±0.51),(1.51±0.56)μm/s;-dL/dt分别为(2.10±0.75),(1.70±0.62),(1.41±0.52)μm/s;FFI分别为(0.38±0.05),(0.35±0.04),(0.25±0.05)。其中C组ph/bl%、 dL/dt、-dL/dt和FFI均较A组显著降低(P<0.05),降低幅度分别为27%,26%,33%和31%。结论随着周龄的增大,分离大鼠心肌细胞的成活率下降,大鼠心肌细胞的收缩/舒张功能降低,钙瞬变幅度减小。     

维拉帕米对心肌细胞肥大的影响

目的研究维拉帕米对心肌细胞肥大的影响及其机制。方法测定培养的心肌细胞［Ｃａ２＋］ｉ和３Ｈ－亮氨酸（３Ｈ－Ｌｅｕ）参入。结果２×１０－７ｍｏｌ／Ｌ维拉帕米对培养的心肌细胞［Ｃａ２＋］ｉ和３Ｈ－Ｌｅｕ参入无明显影响（Ｐ＞０．０５），２×１０－６～１０－５ｍｏｌ／Ｌ维拉帕米则可显著抑制培养的心肌细胞［Ｃａ２＋］ｉ和３Ｈ－Ｌｅｕ参入。与对照组相比，心肌细胞［Ｃａ２＋］ｉ和３Ｈ－Ｌｅｕ参入分别减低１０％～２７％（Ｐ＜０．０１）和１２％～２５％（Ｐ＜０．０５）。结论维拉帕米可以抑制培养的心肌细胞肥大，作用机制可能与其降低细胞内游离钙和细胞收缩性有关。     

有氧运动通过上调心肌细胞自噬改善衰老心肌收缩舒张功能

目的:探讨有氧运动训练能否通过调节心肌细胞自噬改善老年小鼠心肌收缩舒张功能。方法:采用老年C57小鼠(20月龄,10只),以成年小鼠(4月龄,10只)为对照,无负重游泳训练9周(每周5 d,每天1 h),建立有氧运动训练模型。模型建立后,急性分离各组小鼠心肌细胞,采用单心肌细胞动缘探测系统检测心肌收缩舒张能力。应用蛋白免疫印迹法(Western blot)检测自噬相关蛋白的表达。结果:有氧运动训练可有效地改善衰老小鼠心肌收缩舒张能力,表现为可显著增加老年组小鼠心肌细胞最大收缩幅度(PS)和最大收缩和舒张速率(±dL/dt),有效缩短舒张90%时程(TR90)(均P0.05)。有氧运动还可显著上调衰老心肌中单磷酸腺苷活化蛋白激酶(AMPK)磷酸化水平,进而抑制其下游雷帕霉素靶蛋白(mTOR)的活性(均P0.05)。检测心肌自噬标志物Beclin-1和Atg7发现,与成年组相比,老年组小鼠心肌自噬水平显著降低(P0.05),但有氧运动训练可显著改善衰老心肌细胞自噬,运动训练上调心肌细胞自噬的作用,在AMPK基因敲低小鼠(AMPK KD,10只)被显著抑制。采用自噬诱导剂雷帕霉素处理则可改善衰老小鼠心肌收缩舒张的能力(均P0.05)。结论:有氧运动训练可有效地上调衰老小鼠心肌细胞自噬的水平,进而改善衰老小鼠心肌收缩和舒张能力,其机制可能与激活心肌AMPK-mTOR通路有关。     

中药对心肌细胞钙通道作用研究现状

本文综述了近年来利用膜片钳技术研究中药对心肌细胞膜钙通道作用的现状 ,并对未来研究进行展望。心肌细胞膜上电压依赖性钙通道主要有 L 型和 T型两类 ,中药以钙通道拮抗剂居多 ;研究多集中于中药单体     

拉西地平治疗原发性高血压的疗效观察

目的 :观察拉西地平对轻、中度原发性高血压 (EH)的降压疗效及其安全性。方法 :采用自身对照开放试验方法。12 0例 EH患者 ,服安慰剂 1周后口服拉西地平 4～ 8m g(6 5 %服 4～ 6 m g)共 6周 ,不服其他降压药。观察血压、心率及各项实验室检查指标的改变。结果 :服药 6周后血压为 (144 .1± 14) / (85 .9± 7) m m Hg(1m m Hg=0 .133k Pa) ,收缩压下降 2 6 .9mm Hg,舒张压下降 15 .8mm Hg。显效 5 4例 ,有效 5 6例 ,总有效率 91.7%。有不良反应者 14例 (11.6 % ) ,主要为头晕、头痛、面红、心悸等 ,症状较轻不需停药。治疗前后各项血液生化、肝肾功能无改变。结论 :新型长效血管高选择性钙拮抗剂拉西地平对轻、中度 EH患者具有降压作用 ,不良反应少 ,耐受性好。     

拉西地平和氨氯地平对高血压患者左室舒张功能的影响

钙拮抗剂由于可逆转左室肥厚,改善左室舒张功能,现已成为各期高血压、冠心病及肥厚型心肌病治疗的一线药物。第一代二氢吡啶类钙拮抗剂,如硝苯地平,其作用时间短,发挥作用快,导致与血管扩张相关的副作用,新一代二氢吡啶类钙拮抗剂如拉西地平、氨氯地平,作用持久,起效和缓,被大多数患者良好地耐受,作者比较了两者改善心室舒张功能的疗效。1　材料和方法1.1　对象　经病史、查体、超声心动图、心电图、胸部X线及各种化验检查诊断为高血压病,并有左室舒张功能不全(LVDD),且2周内未服用任何抗高血压药物的患者61例,随机分为两组:拉西地平组(L…     

雌激素抑制大鼠心室肌细胞L-型钙电流机制的研究

目的 :探讨雌激素抑制大鼠心肌细胞 L -型钙电流 （ICa,L）的可能途径。方法 :通过胶原酶消化得到单个大鼠心室肌细胞 ,膜片钳全细胞电压钳方法记录 ICa,L。结果 :雌激素 （1～ 30μmol/ L ）可剂量依赖性地抑制 ICa,L,雌激素对ICa,L的抑制作用并不能被雌激素受体的阻断剂 Tamoxifen和 ICI 182 780所阻断。细胞外灌流耦联了牛血清白蛋白（BSA）的雌激素 [β- estradiol6 - （o- carboxy- m ethyl） oxime:BSA（EST- BSA） ],不能透过细胞膜 ]也能抑制 ICa,L,但同样浓度的 EST- BSA细胞内灌流对 ICa,L并没有明显的抑制作用。结论 :雌激素可能是通过膜表面上特异的受体介导了其对 L-型钙电流的抑制作用     

Effects of lidoflazine and mioflazine against potassium and veratrine induced shape changes in isolated rat cardiac myocytes

Summary The protective effects of lidoflazine and mioflazine against shape changes in isolated rat cardiac myocytes induced by depolarizing concentrations of potassium and veratrine have been examined. Myocardial cells, isolated from adult rat hearts and plated in Petri-dishes, yielded a population of nearly 100% rod-shaped calcium-tolerant myocytes. Addition of veratrine or potassium resulted in a calcium-dependent cell shortening and finally rounding up of nearly all cells.Ultrastructurally, the shape changes were accompanied by a complete loss of calcium associated with the sarcolemmal and T-tubular bilayer. Calcium deposits accumulated in the mitochondria, indicating intracellular calcium overload. Pretreatment of the myocytes with lidoflazine or mioflazine (10^–7-10^–5 M) dose-dependently increased the number of remanining rod-shaped cells after potassium or veratrine addition. Such rod-shaped cells retained a normal pattern of calcium distribution along the sarcolemma and T-tubuli with no evidence of mitochondrial calcium overload. The protective effects of lidoflazine and mioflazine are explained in terms of preserving sarcolemmal integrity, whereby excessive calcium influx and subsequent cytosolic calcium overload could be prevented.     

右美托咪定对心室肌细胞L型钙通道电流的影响

目的观察右美托咪定(DEX)对大鼠心室肌细胞L型钙离子通道电流(ICa-L)的影响,探讨其对心脏电活动影响的机制。方法取SD大鼠,用酶解法分离获得单个心室肌细胞,采用全细胞膜片钳技术记录ICa-L,观察不同浓度的DEX(0.6,1.8,5.4,10,200 ng/ml)以及1μmol/L育亨宾(α2肾上腺素受体拮抗剂)单独使用及与10 ng/ml DEX联合使用对ICa-L的影响。结果 0.6,1.8,5.4,10,200 ng/ml的DEX对峰电流的抑制率分别为8.8%±2.4%、14.6%±3.6%、21.4%±8.4%、25.2%±6.4%和32.1%±6.6%,使I-V曲线上移。小剂量(0.6,1.8,5.4 ng/ml)的DEX对ICa-L激活曲线无明显影响(n=6,P>0.05);大剂量(10和200 ng/ml)的DEX可使ICa-L激活曲线右移。0.6,1.8,5.4,10,200 ng/ml的DEX可使ICa-L失活后恢复时间延长。10 ng/ml的DEX可使ICa-L的峰值抑制约25.2%±6.4%,再向电极外液中加入育亨宾后ICa-L平均增加约15%(n=6,P<0.05)。1μmol/L育亨宾灌流前后ICa-L的峰值无差异(n=6,P>0.05)。结论 DEX对心室肌细胞ICa-L具有浓度依赖性地抑制作用,可能是通过细胞膜上的α2肾上腺素受体介导的。     

拉西地平和卡托普利治疗老年人轻中度原发性高血压的比较

目的比较拉西地平和卡托普利治疗老年人轻中度原发性高血压的疗效和安全性。方法经２周安慰剂导入期，５１例患者参加为期１４周随机服用拉西地平或卡托普利开放性对照试验。结果两种药物均能明显降压（Ｐ＜０．００１），拉西地平具有平稳降压效应，谷峰值比率达７６．９％。不良反应发生率，拉西地组为２６．９％（７／２６），卡托普利组为２８．０％（７／２５），差异无显著性。结论对老年高血压患者拉西地平是一种有效、安全且易耐受的降压药，每天１次（４～６ｍｇ）能维持２４小时降压效应。     

Effects of alloimmune injury on contraction and relaxation in cultured myocytes and intact cardiac allografts

Objectives. This study was performed to determine the mechanisms by which allosensitized lymphocytes cause contractile dysfunction in cultured ventricular myocytes and to compare the effects on isolated myocytes with those observed in an intact heart preparation during allograft rejection.Background. Allograft rejection may be associated with reversible abnormalities of both systolic and diastolic function. The immunologic mechanisms that cause ventricular dysfunction are poorly understood.Methods. Vascularized heterotopic abdominal heart transplantation was performed in mice. Contractile function of excised allografts undergoing rejection was assessed using a Langendorff perfusion apparatus and a strain gauge. Spontaneously beating monolayers of cultured ventricular myocytes from donor strain fetal mice were exposed to the allosensitizcd cytotoxic T lymphocytes, and the effects on myocyte motion, intracellular calcium transients, relaxation half-time, membrane potential and myocyte lysis (chromium-51 release) were measured.Results. In intact hearts, histologically mild rejection without myocyte necrosis was associated with decreased systolic function without slowing of relaxation. In cultured fetal myocytes, sensitized lymphocytes induced a progressive decrease in the amplitudes of myocyte motion and calcium transients, with cessation of beating within 40 min. Also, the diastolic membrane potential and amplitude of the action potential decreased. Relaxation half-time, as estimated by measurement of cell motion, was unchanged. The effect was allospecific and was reversible with early removal of lymphocytes from the myocyte monolayer. Pretreatment of lymphocytes with the degranulation inhibitor 4,4′-diisothiocyano-2,2′-disulfonic acid stilbene blocked both the negative inotropic effect and myocyte lysis.Conclusions. We conclude that impaired relaxation is not a prominent feature of contractile dysfunction caused directly in myocytes by alloimmune injury from cytotoxic lymphocytes. Allosensitized lymphocytes can cause reversible systolic dysfunction in myocytes by means of a direct cell-cell interaction. This effect may be in part responsible for the reversible systolic dysfunction associated with allograft rejection.     

Effects of contractile protein phosphorylation on force development in permeabilized rat cardiac myocytes

The phosphorylation status of myofibrillar proteins influences the Ca²⁺ responsiveness of the myofilaments,but the contribution of and the interaction between the individual components is poorly characterized. Therefore, in Langendorff perfused rat hearts (n=30), the phosphorylation levels of cardiac myosin binding protein-C (cMyBP-C), troponin I and T (cTnI, cTnT) and myosin light chain 1 and 2 (MLC-1, MLC-2) were determined by 1- and 2-dimensional gel electrophoresis. Isometric force development, its Ca²⁺-sensitivity, the rate of tension redevelopment (k_tr) and passive force (F_pas) were studied at optimal sarcomere length (2.2 μm) in mechanically isolated,permeabilized cardiomyocytes at 15 °C. Protein phosphorylation was varied by: 1) blocking spontaneous cardiac activity by lidocaine (0.35 mM; Quiescence); 2) electrical stimulation of the hearts at 5 Hz (Contraction) and 3. treatment of contracting hearts with Isoprenaline (1 μM). MLC-2 phosphorylation was increased in the Contraction group almost 2-fold, relative to the Quiescence group, whereas cMyBP-C and cTnI phosphorylation remained the same. Isoprenaline resulted in 3.7-fold increases in both cMyBP-C and cTnI phosphorylation, but did not result in a further increase in MLC-2 phosphorylation.No significant differences were found in maximum force and k_tr between groups, both before and after protein kinase A (PKA) treatment. Ca²⁺-sensitivity in the Contraction and Isoprenaline groups was significantly reduced in comparison to the Quiescence group. These differences were largely abolished by PKA and F_pas was reduced. These results highlight the impact of PKA-dependent phosphorylation on Ca²⁺-sensitivity and provide evidence for an interaction between the effects of TnI and MLC-2 phosphorylation.     

In vitro protective effects of nicorandil on hypothermic injury to immature cardiac myocytes: Comparison with nitroglycerin

Summary The purpose of the present study was to evaluate the functional and biochemical effects of nicorandil and nitroglycerin on cardiac myocytes incubated under hypothermic conditions. Nicorandil is a coronary vasodilator with mixed nitrate-potassium channel agonist activity. Cardiac myocytes were isolated from neonatal rat ventricles and cultured for 4 days with MCDB 197 medium. Myocytes (12.5 × 10⁵ myocytes/flask) were then incubated at 4°C for 24 hours in media containing various concentrations of nicorandil (NRD) or nitroglycerin (NTG). After hypothermic incubation, CPK and LDH were measured. The myocytes were cultured for an additional 24 hours at 37°C to evaluate the recovery of the myocyte beating rate. In the nicorandil group, 10^–4 M NRD showed a significant beating rate recovery compared to control (44.2% vs. 24.6%, respectively, as a percent of control; i.e., beating rate prior to hypothermic incubation). Nitroglycerin treatment had no effect on either beating rate recovery or release of CPK and LDH from myocytes. However, the release of CPK and LDH was significantly suppressed by 10^–4 M nicorandil compared to the control (10^–4 M NRD: 24.1, 257.2; control: 125.4 mIU/flask, 459.5 mIU/flask, respectively). Thus nicorandil showed an approximate two-fold recovery of myocyte functional activity after hypothermic incubation with only minor biochemical effects, and therefore may be suitable for cardiac preservation.