Inotropic effect of different albumin solutions on isolated papillary muscle

We used a papillary muscle assay to study the inotropic effect of albumin solution. Unlike specially prepared citrate-free solutions, commercial preparations produced a negative inotropic effect. This is because their high citrate concentrations bound much of the calcium, so that little ionized calcium was available for physiologic processes. Citrate-free albumin did not show any inotropic effect on isolated papillary muscle. The amount of albumin normally used for resuscitation should not have enough citrate to depress ionized plasma calcium. Our experiments showed no evidence for primary myocardial depressant action of a commercial albumin preparation.     

Anomalous papillary muscle producing dynamic left ventricular outflow tract obstruction.

A patient with a dynamic left ventricular outflow murmur was shown to have an anomalous anterolateral papillary muscle by transthoracic and transesophageal two-dimensional Doppler echocardiography. High late systolic outflow velocity and systolic anterior motion were demonstrated in the lateral outflow tract near the anomalous muscle, suggesting a role for the Venturi effect. This is the first confirmation by Doppler echocardiography of an anomalous papillary muscle contributing to abnormal left ventricular hemodynamics.     

心腔内超声指导左心室前乳头肌消融1例

正患者男,45岁,因"间断心慌半月余"入院。半个月前静坐时无明显诱因突发心慌,持续约10 min,发作时无胸痛、肩背部放射痛、头痛及头晕。心电图示:心房颤动,心房扑动,快速心室率。对症治疗后效果不佳。动态心电图示:不完全性右束支传导阻滞,Ⅱ呈Rs型,Ⅲ、AVF呈R型,V1呈q Rs型,V5呈Rs型,初步判定为左室前乳头肌起源的室上性心动过速。经胸超声心动图示:升主动脉及主动脉窦部增宽,左室收缩及舒张功能正常,主动脉瓣少量反流。经食管超声心动图示:左房及左心耳处未见明     

Effects of hydroxocobalamin on rat cardiac papillary muscle

Hydroxocobalamin is a rapid and powerful antidote in acute cyanide poisoning. The effects of hydroxocobalamin (0.1, 0.3, and 1 mM) on intrinsic myocardial contractility were studied on isolated rat cardiac papillary muscles (n=10). Whatever the concentration, hydroxocobalamin did not modify the active isometric force and a slight increase in maximum unloaded shortening velocity was noted at 1 mM. Only 0.3 mM significantly impaired contraction-relaxation coupling under low load, suggesting a slight decrease in sarcoplasmic reticulum function. No changes in contraction relaxation coupling under heavy load were noted, suggesting the lack of modification of myofilament calcium sensitivity. These results suggest that hydroxocobalamin does not induce noticeable changes in intrinsic myocardial contractility. An indirect mechanism might be involved in the previously reported decrease in cardiac function at supratherapeutic concentrations of hydroxocobalamin.     

The effects of batrachotoxin on cat papillary muscle.

The effects of batrachotoxin (BTX) upon the contraction and transmembrane potential of cat right ventricular papillary muscles were studied in vitro at 37 degrees C. BTX (2.0 x 10(-9) M) increased isometric contractile force by about 50% from control force, decreased the potential difference across the cell membrane to approximate -50 mV and produced spontaneous contractions of the papillary muscles. Each BTX-induced spontaneous contraction was accompanied by a spontaneous action potential which was generated when an oscillation in membrane potential reached threshold level. Spontaneous activity ovvurred only in muscles which were previously stimulated electrically. The positive inotropic effect of BTX was accompanied by an increase in the rate of force development. Papillary muscles from cats pretreated with reserpine did not differ from normal muscles in their responses to BTX treatment. Tetrodotoxin (2.0 x 10(-7) M) antagonized the effects of BTX, a finding which suggests that the actions of BTX are mediated by a selective increase in membrane permeability to sodium ions. The resultant BTX-elicited increase in the intracellular sodium ion concentration may increase the force of contraction through an augmentation of calcium influx via the sodium-calcium exchange system.     

Comparative ultrastructure of the tip of ventricular papillary muscle.

Electron microscopic studies of the tips of left ventricular papillary muscles from seven human, two monkey, three sheep, and two chicken hearts were done to elucidate the fine structure of myotendinous junctions. The human specimens were from normal hearts obtained 3 to 9 hours postmortem from persons aged 7 months to 30 years (mean, 13.3 years). We found no significant ultrastructural differences between the human hearts and those of monkey, sheep, and chicken. Myocardial fibers were elongated and thinner (tapered) in the tips of papillary muscles. In addition to usual working myocardial cells, the distal end of narrowing muscle fibers also contained small pale cardiocytes containing fewer myofibrils and smaller mitochondria. These cells were similar to P cells or transitional cells in the conduction system. Nerve axons and Schwann cells were commonly seen in the interstitium, usually in association with capillaries. Fibroblasts and axon varicosities were occasionally seen extremely close to the cardiocytes. These specialized myocardial cells associated with rich neural tissue in the papillary muscle tip possibly function as foci of local automaticity. This histologic organization may also represent neurosensory function responding to and monitoring local pressure changes, efferent adrenergic or cholinergic neural activity, or both.     

Ultrasound intensity and contractile characteristics of rat isolated papillary muscle

The effect of graded intensities of continuous wave ultrasound on the contractile performance of isolated papillary muscle of rat was tested. Under isometric conditions rat left ventricular papillary muscles (n = 48) were electrically stimulated to contract at rates of 30, 60, 120 and 240 beats per minute. Muscles were perfused with a Tyrode solution at 30 degrees C under normoxic conditions. Ultrasound at intensities of 0.25, 0.50, 1.0 and 2.0 W/cm2 spatial average temporal average (SATA) at 963 kHz was applied to the muscles while recording muscle contractile characteristics. The analog data were digitized and stored on disk for analysis by computer. This revealed a significant (p less than 0.001) increase in peak developed force (F), peak rate of force development (+dF/dt) and peak rate of myocardial relaxation (-dF/dt) that was linearly related to ultrasound intensity. The muscles were more sensitive to ultrasound at 240 contractions per minute. Resting force was significantly decreased by ultrasound. Although bath temperature increased according to the ultrasound intensity, control studies in papillary muscles (n = 24) on the correlation between contractile parameters and temperature revealed that bulk heating could not account for the positive inotropic action with ultrasound. These data confirm the inotropic effect of continuous wave ultrasound on myocardial tissue and point to the possibility of applying this phenomenon therapeutically.     

Inotropic and chronotropic effects of vasodilators

Although vasodilators are used with increasing frequency for the treatment of heart failure and myocardial ischemia, their direct effects on cardiac muscle have not been completely characterized. To delineate the action of vasodilators on mammalian myocardium, the chronotropic and inotropic effects of vasodilators on isolated guinea-pig atria (n = 163) have been determined. The spontaneous frequency and the peak rate of isometric force development at a fixed frequency of 200/min were used as indexes of chronotropy and inotropy. The potency series for negative chronotropy was diltiazem greater than D600 greater than verapamil greater than lidoflazine greater than bepridil greater than prenylamine greater than perhexiline greater than nifedipine. The potency series for negative inotropy differed substantially, exhibiting the sequence nifedipine greater than D600 greater than verapamil greater than bepridil greater than lidoflazine greater than prenylamine greater than perhexiline greater than diltiazem. Therefore, nifedipine acted as an "inoselective" and diltiazem as a "chrono-selective" depressant. Other vasodilators, including papaverine, nitroglycerin, nitroprusside, adenosine, dipyridamole, diazoxide and hydralazine exerted no or negligible negative chronotropic or inotropic effects even at high concentration (10(-5) M). Therefore, only vasodilators classified among the calcium antagonists proved to have appreciable direct myocardial effects. This supports the view that these drugs constitute a category of agents distinct from classical vasodilators.     

以不同方式处理肌小梁和乳头肌后基于心脏MRI所测中国健康成人左心室结构和功能参数的差异

目的 基于心脏MRI(CMRI)以不同方式处理肌小梁和乳头肌(TPM)后观察中国健康成人左心室结构和功能的差异。方法 回顾性分析168名中国健康成人,包括男105名、女63名的CMRI资料。分别采用标准(将TPM包含于血池内)和精细(将TPM包含在心肌组织中)方法测量左心室舒张末期容积(EDV)、 收缩末期容积(ESV)、每搏输出量(SV)及射血分数(EF),对比其间左心室结构和功能参数的差异。随机选取50名受试者,由2名观察者以相同方法测量上述参数,分析观察者间测量结果的一致性及其变异系数(CV)。结果 相比标准方法测量结果,以精细方法所测全部、男性及女性受试者的EDV、ESV和SV均较小,而EF较大(P均＜0.001);经体表面积校正后,以2种方法所获全部、男性及女性受试者EDV、ESV和SV差异均有统计学意义(P均＜0.001)。观察者间以标准方法所获左心室EDV、ESV和EF的一致性均极好(ICC=0.90~0.94)、CV为3.10%~5.29%,以精细方法所测上述参数的一致性为好至极好(ICC=0.85~0.95),CV为4.36%~9.74%。结论 基于CMRI以不同处理TPM方式所测中国健康成人左心室结构和功能参数存在差异。     

犬左室乳头肌的导管超声消融

背景：近年来的研究表明左室乳头肌在室性心律失常的发生中起到了重要的作用。目的：在经胸超声图像监控下,观察自制的超声消融导管消融动物左室乳头肌的可行性和安全性。方法：普通杂种犬9只,随机分为2组：对照组3只,消融组6只。3％戊巴比妥钠麻醉后于无菌条件下分离其颈动脉并置入8F动脉鞘管,行机械通气并记录体表心电图,导管在经胸超声的引导下达到左心室腔,通过经胸超声图像调整导管与乳头肌的贴靠关系,保持导管与乳头肌贴靠良好,随后以声强50W／cm2、时间60s消融左室乳头肌。结果与结论：所有动物在观察期内均正常存活,乳头肌等解剖结构经胸超声图像显示清楚,并能通过经胸超声图像明确导管与乳头肌的相对位置及贴靠情况,切开动物心肌后,大体可见乳头肌内消融灶与周围正常心肌组织界限清晰,中央区呈白色,绕以淡红色的周边区。光镜下见消融灶与周边组织界线分明,灶内心肌细胞坏死,细胞间隙增宽,大量红细胞浸润。无附壁血栓、心肌灼伤及穿孔和心脏破裂等手术相关并发症。可见在经胸超声的实时监控下,能够实现导管对乳头肌深部组织安全有效的消融。     

Differential effects of chlorpromazine on two vasoconstrictor tones in the rat.

Hindquarter compensator tone (HCT) is referred to as the sympathetic vasoconstrictor tone to the hindquarters of the rat induced by such hypotensive interventions as pentobarbital anesthesia, nitrate administration and blood loss. The aim of this study is to observe whether chlorpromazine (CPZ) injected intravenously in rats (0.5 mg/kg) inhibits the following two different kinds of vasoconstrictor tone: HCT induced by pentobarbital and the renal tone which is normally present in the conscious state. Rats were implanted with an electromagnetic flow probe around the terminal aorta or the left renal artery. The right common carotid was cannulated for mean arterial pressure (AP). Regional peripheral resistance (hind-quarter resistance [HQR] or renal resistance [RR]) was calculated as AP divided by regional flow. In rats under pentobarbital anesthesia, after CPZ, ganglionic blockade with hexamethonium bromide (25 mg/kg) did not decrease HQR. However, in conscious rats after CPZ, blockade decreased RR significantly. These findings indicate that CPZ inhibits HCT almost completely but scarcely decreases the renal tone and further suggest that HCT and the renal tone are generated by different mechanisms.     

莫索尼定降压及逆转左室肥厚的临床效果观察

目的探讨莫索尼定降压效果和逆转患者左室肥厚的作用。方法将80例高血压合并左室肥厚患者分为莫索尼定(治疗)组和卡托普利(对照)组治疗,观察6个月,比较两组血压(BP)和左心室肥厚的变化。结果莫索尼定治疗使BP从(163.5/80.7±16.7/10.5)mmHg降至(125.7/71.3±13.6/8.53)mmHg(P<0.05),左心室质量指数(LVMI)从(145.8±13.0)g/m2降至(122.3±11.8)g/m2(P<0.05),但治疗组的BP和LVMI变化与对照组之间比较无差异。结论莫索尼定具有显著降压作用,长期使用能够显著逆转左心室肥厚。     

卡维地洛对肾性高血压大鼠左室重构影响的实验研究

目的:观察第三代β受体阻滞剂卡维地洛防治肾性高血压大鼠左室重构的作用。方法:建立两肾一夹(2K1c)大鼠肾血管性高血压左室重构模型。术后8周随机分成3组:(1)假手术组(n=8);(2)2K1c组(n=8);(3)卡维地洛组(n=8)。治疗组直接灌胃给药。12周后行血流动力学分析,应用病理学方法评价整体心肌肥厚和组织胶原的表达,免疫组化方法检测MMP-2、TIMP-2的表达情况。结果:与假手术组相比,2K1c组大鼠术后发生明显左心室肥厚和纤维化,收缩压(SBP)、左室收缩压(LVSP)、左室舒张末压(LVEDP)、左室重量(LVM)、左室重量指数(LVMI)、胶原的含量及MMP-2、TIMP-2的表达显著高于健康的对照组(P<0.01),左室最大收缩和舒张速率(±dp/dtmax)均显著降低。卡维地洛能降低SBP、LVSP、LVEDP、LVM,而±dp/dtmax均显著升高;减少左室心肌中总体胶原中的合成及MMP-2、TIMP-2表达。结论:MMP-2、TIMP-2与左心室肥厚细胞外基质有关,卡维地洛能改善血流动力学和左室功能,有效地防止肾性高血压大鼠左室重构。     

经多功能导管化学消融犬左心室前组乳头肌

目的 观察利用多功能心腔内超声（ICE）导管化学消融犬左心室前组乳头肌（APM）的可行性。方法 将15只杂交犬随机分均为0.2 ml组、0.4 ml组及0.8 ml组，每组5只。在ICE图像定位和监控下于左心室APM基底部注射不同剂量无水乙醇进行化学消融。于消融前及消融5天后行经胸超声，检测二尖瓣反流面积（MRA）及射流紧缩口宽度（VC）。之后处死动物，观察APM大体及病理变化。结果 ICE图像可清晰显示左心室APM结构，并实时监测进针深度及消融过程。消融5天后0.2 ml及0.4 ml组MRA、VC无明显改变，0.8 ml组MRA及VC较消融前明显增加（P均<0.05）。APM基底部可见中央呈苍白色的消融灶，0.2 ml、0.4 ml及0.8 ml无水乙醇在APM基底部形成的消融灶体积分别为（0.37±0.07）cm²、（0.69±0.08）cm²、（0.96±0.19）cm²，较高剂量组消融灶体积均大于较低剂量组（P均<0.05）。光镜下见消融灶内心肌细胞呈不可逆性坏死改变。结论 采用ICE导管注射低剂量无水乙醇可安全、有效消融左心室APM，有望为治疗左心室APM起源室性心律失常提供新的策略。     

二维斑点追踪技术评价正常成人左心室乳头肌收缩功能

目的 应用二维斑点追踪成像(STI)评价正常成人左心室乳头肌的收缩功能。 方法 选取30名健康成年人,应用STI得到乳头肌及其基底部心室壁应变曲线,测量前外乳头肌纵向收缩峰值应变(ALP-LS)及应变达峰时间(ALP-Ts)、前外乳头肌基底部心室壁纵向收缩峰值应变(ALW-LS)及应变达峰时间(ALW-Ts)、后内乳头肌纵向收缩峰值应变(PMP-LS)及应变达峰时间(PMP-Ts)、后内乳头肌基底部心室壁纵向收缩峰值应变(IPW-LS)及应变达峰时间(IPW-Ts)。比较前外、后内乳头肌应变及各部位应变达峰时间的差异。 结果 30名受检者平均ALP-Ts为(451.23±44.03)ms,ALW-Ts为(364.53±48.13)ms,差异有统计学意义(t=13.059,P<0.001);平均PMP-Ts为(450.57±47.90)ms,IPW-Ts为(356.77±42.04)ms,差异有统计学意义(t=13.643,P<0.001);而ALP-Ts与PMP-Ts、ALP-LS与PMP-LS的差异均无统计学意义(P均>0.05)。 结论 正常成人左心室乳头肌的纵向收缩应变达峰时间延迟于相应乳头肌基底部室壁,前后两组乳头肌的收缩运动可能具有同步性。     

Protective effects of bepridil on calcium injury of anoxic myocytes isolated from adult rat heart ventricular muscle

Cardiac myocytes allowed to recover after the isolation procedure in a well-oxygenated medium were resistant to an extracellular Ca++ concentration of 1.5 mM. At least 90% of the isolated myocytes maintained their initial rod-shaped form after a 1-hr incubation, as well as 85% of their ATP and a low cellular content of calcium. At concentrations less than 10(-5) M, bepridil had no effect on these cells. On the other hand, when the myocytes were incubated in anaerobic conditions, 1.5 mM Ca++ was deleterious: the number of viable cells decreased by about 50%, ATP levels were lowered by 70% and the total cell calcium content increased by more than 100%. Bepridil had a biphasic effect on anaerobic cells. At concentrations below 10(7) M, the drug had a beneficial action. It restored cell viability and cellular ATP to 77 and 100% when compared to their respective level in the absence of Ca++. However, at concentrations higher than 10(-6) M, bepridil decreased the number of viable cells as well as their ATP content. At optimal concentrations, bepridil lowered the cellular calcium to its level in aerobic conditions. Without calcium addition, anoxic cells accumulated Na+ and lost K+. Calcium addition decreased Na+ accumulation by 68% and prevented the loss of K+. The Na+ and K+ content of the cells were not affected by bepridil. However, it is noteworthy that, at 10(-4) M, bepridil decreased dramatically the potassium content of the cells. In aerobic conditions, the calcium resistance of isolated ventricular myocytes may still be enhanced by Fluozol, a fluorocarbon compound which increases oxygen solubility in water.