羊角拗苷对豚鼠心室肌细胞内游离钙离子浓度的影响

目的观察羊角拗苷(Div)对豚鼠心室肌细胞内游离钙离子([Ca2+]i)浓度的影响,以探讨Div正性肌力作用的机制。方法Fura-2/AM荧光探针标记豚鼠心室肌细胞,应用荧光离子成像系统观察Div800nmol.L-1对心室肌细胞[Ca2+]i的影响。结果在正常台氏液中,Div使心室肌细胞[Ca2+]i显著升高(243±36)%,在无钙液中对[Ca2+]i无明显影响。在无Na+、无K+台氏液中,Div使[Ca2+]i升高(96±20)%。给予L型钙通道阻滞剂CdCl2100μmol.L-1预处理后,Div仍使[Ca2+]i升高(63±10)%。给予T型钙通道阻滞剂NiCl240μmol.L-1预处理后,Div引起的[Ca2+]i升高基本被阻断。结论体外应用Div800nmol.L-1时使豚鼠心室肌细胞[Ca2+]i升高,该升高作用依赖于细胞外Ca2+的存在,可能主要由T型钙通道介导,L型钙通道和Na+-Ca2+交换蛋白亦参与其中。其正性肌力作用与心室肌细胞[Ca2+]i升高有关。     

无创性肢体缺血预适应对大鼠心脏的保护作用

目的研究无创性肢体缺血预适应(RIP)对大鼠缺血/再灌后心脏损伤的影响。方法采用无创性后肢缺血预适应的方法,观察其对心肌缺血/再灌后心脏生理学(HR、MAP、ST段)、室性心律失常的出现时间和持续时间的影响以及其对心肌缺血/再灌后梗死面积和形态学改变的影响。结果与对照组比较,处理组对心肌缺血/再灌后HR和MAP的影响差异无显著性,但是RIP能明显降低ST段的抬高幅度,推迟室性心律失常出现的时间,缩短持续时间,并且能减少心肌梗死面积,降低心肌细胞的肿胀、减少间质出血和炎性细胞的浸润。结论RIP对心肌损伤具有保护作用。     

高密度脂蛋白对缺血再灌注大鼠心肌损伤保护作用的研究

目的 探讨高密度脂蛋白(HDL)预处理对大鼠心肌缺血再灌注的影响.方法 将42只SD大鼠随机分为假手术组(S组)、缺血再灌注组(IR组)和缺血再灌注HDL预处理组(H/IPC).以穿线结扎左冠状动脉制备心肌缺血再罐注模型,H/IR组缺血前10 min经尾静脉注入HDL(30 mg/kg).检测3组大鼠缺血再灌注后30、60、120、240 min血清肌酸激酶(CK)、细胞间黏附分子-1(ICAM-1)的含量;观察3组大鼠缺血再灌注后120 min心肌组织病理学变化.结果 H/IPC组与IR组比较,大鼠CK、ICAM-1含量均降低,下降率分别为36.5%、32.0%、12.6%(P＜0.01);S组CK、ICAM-1含量明显低于IR组(P＜0.01),S组心肌纤维大小均匀、线粒体结构清楚;与IR组比较,H/IPC组伤后240 min心肌细胞变性、炎性细胞浸润及线粒体肿胀程度减轻,且未见细胞溶解坏死.结论 HDL对大鼠心功能的保护作用,可能与HDL抑制ICAM-1的表达有关.     

家兔未成熟心肌摄钙功能的实验

目的：从亚细胞水平研究未成熟心肌缺血-再灌注损伤中肌浆网(sarcoplasmic reticulum，SR)摄钙功能，及其mRNA表达．方法：将48只兔随机分为4组，进行Langendorff灌注．组I：幼兔，单纯灌注30min；组Ⅱ：幼免，灌注30min，停搏60min，再灌注30min。组Ⅲ和组IV为成免，处理分别同组I和组Ⅱ，进行对照．测定各组心功能、冠状动脉流出液血气，单细胞内游离钙离子浓度([Ca^2 ]i)，肌浆网钙离子—三磷酸腺苦酶(sarcoplasmic reticulum Ca^2 -adenosine triphosphatase,SR Ca^2 -ATPase)活性，肌浆网^45Ca^2 摄取，并用斑点杂交(dot blot)检测SR Ca^2 —ATPase mRNA表达．结果：缺血—再灌注后，成熟与末成熟心肌均发生钙超载(P＞0．05)．成熟心肌SR Ca^24—ATPase活性，SR ^45Ca^2 摄取初始量，SR^45Ca^2 摄取最大量明显减弱，SR Ca^2 —ATPase mRNA表达明显上调，未成熟心肌则变化不明显，两相比差异显(P＜0．05)．结论：缺血—再灌注后，未成熟心肌SR Ca^2 —ATPase活性恢复率，SR ^45Ca^2 摄取恢复率，明显高于成熟心肌，SR Ca^2 —ATPase mRNA表达上调明显低于成熟心肌．未成熟心肌缺血—再灌注损伤钙超载机制不同于成熟心肌：SR钙摄取功能在钙超载损伤中不起主要作用．     

Acidic HEPES-KH Reperfusion Enhances Myocardial Protection in Immature Rabbits

Summary: To study the effects of different pH HEPES-KH reperfusate solution on immature myocardial protection, isolated perfused Langendorff model from immature rabbit hearts were developed formed. Control group (C) was perfused only with pH 7. 4 HEPES-KH solution for 90 min. Is chemia/reperfusion group (group I/R) was perfused with pH 7. 4 HEPES-KH solution before is chemia or after ischemia. Experimental group (group E), after ischemia, was perfused with pH 6.8,pH 7. 1 and pH7.4 HEPES-KH solutions for 5 min, 5 min, and 20 min, respectively. The left ven tricular function recovery, MWC, LDH and CK leakage, MDA, ATP content, and SOD activity were determined. Our results showed that the left ventricular function recovery, ATP content and SOD activity in group E were higher than those of group I/R (P＜0. 05). MWC, MDA content,LDH and CK leakage in group E were lower than those of group I/R (P＜0. 05). These findings suggested that pH paradox might be one of important mechanisms for immature myocardial ischemia reperfusion injury, and acidic perfusate, at the beginning of reperfusion, might attenuate pH paradox and ameliorate functional recovery in isolated perfused immature rabbit hearts.     

GLUCOSE INFUSION IN THE PREGNANT RABBIT AND ITS EFFECT ON GLYCOGEN CONTENT AND ACTIVITY OF FOETAL HEART UNDER ANOXIA1

The object of the present study was to determine the possibility of increasing the glycogen content of the foetal myocardium, and thus its ability to survive under anoxic conditions, by infusing glucose in the mother animal before delivery. The material consisted of 41 rabbits; 23 were given a glucose infusion, and 18 served as controls. On the 29th day of pregnancy, a solution of 30% glucose was infused over a 6-hour period. Immediately after the infusion, the mother was sacrificed, and the foetuses delivered abdominally. They were maintained at 37°C, but without the possibility of lung aeration. The ECG of one foetus in each litter was recorded until no heart activity remained. Concurrently, the other foetuses were sacrificed at irregular intervals, and studied with respect to the glycogen content of heart and liver, blood pH and blood glucose. These parameters were correlated to foetal heart activity. It was found that glucose infusion in the mother did, in fact, increase the glycogen content of the foetal heart. This, in turn, seemed to increase the ability of the foetal heart to continue its activity under anoxic conditions.     

Recovery of contractile function of cryodamaged rat myocardium after transplantation of fetal cardiomyocytes and predifferentiated bone marrow stromal stem cells

The effect of cell transplantation into cryodamaged rat myocardium was studied on isolated hearts by increasing functional load to the left ventricle. Transplantation of allogeneic fetal cardiomyocytes improved the function of the left ventricle under conditions of considerably increased preload. Transplantation of autologous mesenchymal stem cells repaired leftventricular function under conditions of increased pre- and afterload.Translated from Byulleten Eksperimentalnoi Biologii i Meditsiny, Vol. 138, No. 10, pp. 403–407, October, 2004     

Cryptococcal capsular glucuronoxylomannan reduces ischaemia-related neutrophil influx

Background The capsular polysaccharide glucuronoxylomannan (GXM) of Cryptococcus neoformans interferes with the chemotaxis and transendothelial migration of neutrophils. Intravenous administration of purified GXM has been shown to reduce the influx of inflammatory cells in an animal model of bacterial infection. Here we show that isolated GXM can also interfere with neutrophil migration in a model of inflammation not related to infection. We assessed the effects of intravenous GXM on neutrophil infiltration in a rat model of myocardial ischaemia, where neutrophil infiltration has been shown to contribute to postischaemic reperfusion injury. Materials and methods Rats were subjected to coronary artery ligation followed by a 3‐h reperfusion period. Myeloperoxidase‐activity was measured in the ischaemic tissues as a marker of neutrophil infiltration. Results Intravenous administration of GXM markedly reduced the influx of neutrophils in the ischaemic myocardium as measured by a 65% reduction of tissue MPO activity. This reduction of MPO activity was clearly correlated to the serum concentration of GXM. As complement activation by GXM was minimal at the doses applied in vivo, it is unlikely that generation of chemotactic C5a in the circulation by GXM caused the observed reduction in leucocyte migration. Conclusion Purified cryptococcal GXM has the ability to reduce neutrophil influx even outside the scope of infection.     

Scatter correction on its own increases image contrast in TI-201 myocardium perfusion scintigraphy,but does it also improve diagnostic accuracy?

Poor and variable spatial resolution of the gamma camera, the movement of the heart and, above all, the inclusion of scattered photons in the acquisition data contribute to the deterioration of image contrast in 201Tl myocardium perfusion studies. Scatter correction algorithms may correct for the latter factor by removing (most of) the scattered photons from the acquisition data. METHODS: In this study we investigated the contrast changes induced by the Triple Energy Window scatter correction method (TEW) applied to clinical 201Tl myocardium perfusion studies and its influence on the reading of the images. Stress and rest studies of 30 consecutive patients were used for this study. Maximum image contrasts were measured between the myocardium and the left ventricular cavity in four mid-ventricular short axis slices, as well as between normally and abnormally perfused myocardium using bull's-eye displays of the activity within the myocardium. To assess image quality and perfusion abnormalities, an experienced nuclear medicine physician, blind to patient characteristics, visually reviewed all studies. RESULTS: In all individual measurements, the maximum contrast after scatter correction was higher than without correction (p < 0.001). The average increase in contrast between the myocardium and the left ventricular cavity was 43% and 48% for stress and rest studies respectively. The contrast within the myocardium increased by 25% and 32% respectively. After TEW, image quality was rated lower in almost half of the studies, while in only one study the quality was rated higher. In stress studies 11 additional perfusion defects were observed, with rest studies revealing 15 more defects after TEW, but this difference was not significant. Cohen's kappa indicated a moderate agreement of the image reading between studies with and without scatter correction. CONCLUSION: We conclude that image contrast improves significantly by scatter correction. However, image quality decreased as a result of an unfavorable signal-to-noise ratio. As an overall result, no significant change in the clinical outcome of the studies could be shown. Additional training of the readers may be required to obtain optimal results.     

Myocardial delineation via registration in a polar coordinate system

Rationale and Objectives. Cardiovascular disease is the number one cause of premature death in the western world. Analysis of cardiac function provides clinically useful diagnostic and prognostic information; however, manual analysis of function via delineation is prohibitively time consuming. This article describes a technique for analysis of dynamic magnetic resonance images of the left ventricle using a non-rigid registration algorithm. A manually delineated contour of a single phase was propagated through the dynamic sequence.

Materials and Methods. Short-axis cine magnetic resonance images were resampled into polar coordinates before all the time frames were aligned using a non-rigid registration algorithm. The technique was tested on 10 patient data sets, a total of 1,052 images were analyzed.

Results. Results of this approach were investigated and compared with manual delineation at all phases in the cardiac cycle, and with registration performed in a Cartesian coordinate system. The results correlated very well with manually delineated contours.

Conclusion. A novel approach to the registration and subsequent delineation of cardiac magnetic resonance images has been introduced. For the endocardium, the polar resampling technique correlated well with manual delineation, and better than for images registered without radial resampling in a Cartesian coordinate system. For the epicardium, the difference was not as apparent with both techniques correlating well.