常用麻醉剂对麻醉小鼠超声心功能的影响

目的:比较常见的多种麻醉剂对小鼠心脏超声结果的影响。方法:C57BL/6小鼠25只,随机分5组,每组5只。首先在清醒状态下,借助小动物高频超声系统(Vevo2100)评价小鼠心功能,然后分别用戊巴比妥钠、水合氯醛、三溴乙醇、氯胺酮/地西泮及异氟烷麻醉,再次对心功能进行评价。比较6种不同处理情况下,超声反映的小鼠心功能的差异。结果:与清醒状态相比,5种麻醉方式下,小鼠的心率及心功能均有不同程度降低。其中,戊巴比妥钠、水合氯醛、三溴乙醇及异氟烷麻醉组的左心收缩功能显著降低(P0.01),而氯胺酮/地西泮麻醉的小鼠与清醒组相比,收缩功能无明显差异(P0.05),但其余参数也有显著差异(P0.01)。结论:不论何种麻醉方式,都会对小鼠心率及心功能造成一定影响,但其同组内仍具有可比性;因此应根据现实条件及实验需要选择麻醉剂,并贯彻始终,保持试验中麻醉条件的一致性。     

A time-course study of the effects of pentobarbital, fentanyl, and morphine chloralose on myocardial mechanics.

Cardiovascular physiological studies in anesthetized animals may be confounded by the hemodynamic actions of the anesthetic agents themselves. To identify an anesthetic regimen that does not significantly influence cardiovascular physiology, the hemodynamic responses of 28 dogs were studied. Animals were equally divided among groups with 1) no anesthesia (i.e., trained conscious preparation), 2) pentobarbital sodium, 3) fentanyl citrate, and 4) a combination of morphine sulfate and alpha-chloralose. Anesthesia was maintained for 3 h. Data were acquired with the use of ultrasound imaging of the heart in conjunction with invasive pressure measurements. Left ventricular ejection phase indexes and end-systolic force-velocity relations were used to evaluate the effects of each anesthetic agent on overall systolic performance and myocardial contractility. Compared with the conscious animals, pentobarbital profoundly depressed systolic performance (P less than 0.05 vs. control) because of a reduction in myocardial contractility (P less than 0.01) and an increase in left ventricular afterload (end-systolic wall stress, P less than 0.05). Fentanyl increased myocardial contractility (P less than 0.05) but also tended to increase afterload with the net result that overall systolic performance remained unchanged. Morphine-chloralose did not affect overall ventricular systolic performance or its individual determinants. Pentobarbital and fentanyl also caused progressive time-dependent deteriorations in all parameters of systolic function during prolonged anesthesia. In contrast, cardiac function was stable for greater than or equal to 3 h after induction of morphine-chloralose anesthesia. The hemodynamic profile of dogs anesthetized with morphine-chloralose most closely resembled that of the conscious animals. Morphine-chloralose is recommended when prolonged anesthesia is required for studies of cardiovascular physiology.     

Determination of cardiac contractility in awake unsedated mice with a fluid-filled catheter

Today, cardiac contractility in mice is exclusively measured under anesthesia or in sedated animals because the catheters available are too rigid to be used in awake mice. We therefore developed a new catheter (Pebax 03) to measure cardiac contractility in conscious mice. In this study, we evaluated the accuracy and utility of this new catheter for assessment of cardiac contractility in anesthetized and conscious mice. With the use of a balloon-pop test, the Pebax catheter with an inner diameter of 0.3 mm was found to exhibit a high natural frequency, a low damping coefficient, and a flat frequency of up to 50.5 +/- 0.6 Hz. Under anesthesia (0.5% or 1.0% halothane), no difference was found in heart rate (HR), left ventricular (LV) systolic pressure (LVSP), the maximum rates of LV pressure rise and fall (LV dP/dt(max) and LV dP/dt(min), respectively), ejection time (ET), and isovolumic relaxation time constant (tau) when measured with either the 1.4-Fr Millar or Pebax 03 catheter. However, when HR, LVSP, LV dP/dt(max), and LV dP/dt(min) were recorded with the Pebax catheter in awake mice, values were significantly higher, and ET and tau were lower, than under anesthesia, suggesting a major impact of anesthesia on these parameters. The Pebax catheter was also used in a normotensive one-renin gene mouse model of cardiac hypertrophy induced by DOCA and salt. In this model, DOCA-salt induced a severe decrease in cardiac contractility in the absence of changes in blood pressure. These data demonstrate that cardiac contractility can be measured very accurately in conscious mice. This new device can be of great help in the investigation of cardiac function in normal and genetically engineered mice.     

New technique for measurement of left ventricular pressure in conscious mice

Concern about the effects of anesthesia on physiological measurements led us to develop methodology to assess left ventricular (LV) pressure in conscious mice. Polyethylene-50 tubing filled with heparinized saline was implanted in the LV cavity through its apex via an abdominal approach and exteriorized to the back of the animal. This surgery was done under anesthesia with either an intraperitoneal injection of ketamine (80 mg/kg) and xylazine (5 mg/kg) (K+X) in 11 mice or isoflurane (ISF; 1.5 vol%) by inhalation in 14 mice. Postoperatively, mice were trained daily to lie quietly head first in a plastic cone. LV pressure, the first derivative of LV pressure (dP/dt), and heart rate (HR) in the conscious state were compared between the two groups at 3 days and 1 wk after recovery from surgery using a 1.4-Fr Millar catheter inserted into the LV through the tubing, with the mice lying quietly in the plastic cone. Acutely during anesthesia, K+X decreased HR (from 698 to 298 beats/min), LV systolic pressure (from 107 to 65 mmHg), and maximal dP/dt (dP/dt(max)) (from 15,724 to 4,445 mmHg/s), all P < 0.01. Similar but less marked negative chronotropic and inotropic effects were seen with ISF. HR and dP/dt(max) were decreased significantly in K+X mice 3 days after surgery compared with those anesthetized with ISF (655 vs. 711 beats/min, P < 0.05; 14,448 vs. 18,048 mmHg/s, P < 0.001) but increased to the same level as in ISF mice 1 wk after surgery. In ISF mice, recovery of function occurred rapidly and there were no differences in LV variables between 3 days and 1 wk. LV pressure and dP/dt can be measured in conscious mice with a micromanometer catheter inserted through tubing implanted permanently in the LV apex. Anesthesia with either K+X or, to a lesser extent, ISF, depressed LV function acutely. This depression of function persisted for 3 days after surgery with K+X (but not ISF) and did not recover completely until 1 wk postanesthesia.     

培养于生物降解支架膜内的胚胎干细胞可修复小鼠的梗塞心肌

我们以往的研究表明,直接在心肌梗塞（myocardial infarction,MI）动物的心脏缺血区注射胚胎干细胞（embryonic stemceils,ESCs）可以提高其心肌功能,干细胞组织工程学可以使组织再生、修复。本研究旨在观察将ESCs接种到生物降解膜内并移植到梗塞部位的效果。通过结扎小鼠左冠状动脉制作MI模型,将培养3d的带有小鼠ESCs的聚羟基乙酸膜（polyglycolicacid,PGA）移植到心肌缺血及边缘区表面。实验小鼠分成4组：假手术组、MI组、MI＋PGA组、MI＋ESC组,移植操作8周后检测血流动力学和心肌功能。MI组的血压和左心室功能显著降低。与MI组和MI＋PGA组相比,MI＋ESC组的血压和心室功能显著改善,存活率也显著增高,在梗塞区检测到GFP阳性组织,表明ESCs存活,并可能有心肌再生。以上结果表明,移植生物降解膜内的ESCs可修复小鼠梗塞区心肌细胞并提高心脏功能。将ESCs和生物降解材料联合运用可能为修复受损心脏提供一个新的治疗方法。     

Effects of avertin versus xylazine-ketamine anesthesia on cardiac function in normal mice

Anesthetic regimens commonly administered during studies that assess cardiac structure and function in mice are xylazine-ketamine (XK) and avertin (AV). While it is known that XK anesthesia produces more bradycardia in the mouse, the effects of XK and AV on cardiac function have not been compared. We anesthetized normal adult male Swiss Webster mice with XK or AV. Transthoracic echocardiography and closed-chest cardiac catheterization were performed to assess heart rate (HR), left ventricular (LV) dimensions at end diastole and end systole (LVDd and LVDs, respectively), fractional shortening (FS), LV end-diastolic pressure (LVEDP), the time constant of isovolumic relaxation (tau), and the first derivatives of LV pressure rise and fall (dP/dt(max) and dP/dt(min), respectively). During echocardiography, HR was lower in XK than AV mice (250 +/- 14 beats/min in XK vs. 453 +/- 24 beats/min in AV, P < 0.05). Preload was increased in XK mice (LVDd: 4.1 +/- 0.08 mm in XK vs. 3.8 +/- 0.09 mm in AV, P < 0.05). FS, a load-dependent index of systolic function, was increased in XK mice (45 +/- 1.2% in XK vs. 40 +/- 0.8% in AV, P < 0.05). At LV catheterization, the difference in HR with AV (453 +/- 24 beats/min) and XK (342 +/- 30 beats/min, P < 0.05) anesthesia was more variable, and no significant differences in systolic or diastolic function were seen in the group as a whole. However, in XK mice with HR <300 beats/min, LVEDP was increased (28 +/- 5 vs. 6.2 +/- 2 mmHg in mice with HR >300 beats/min, P < 0.05), whereas systolic (LV dP/dt(max): 4,402 +/- 798 vs. 8,250 +/- 415 mmHg/s in mice with HR >300 beats/min, P < 0.05) and diastolic (tau: 23 +/- 2 vs. 14 +/- 1 ms in mice with HR >300 beats/min, P < 0.05) function were impaired. Compared with AV, XK produces profound bradycardia with effects on loading conditions and ventricular function. The disparate findings at echocardiography and LV catheterization underscore the importance of comprehensive assessment of LV function in the mouse.     

The Role of 1.5 Tesla MRI and Anesthetic Regimen Concerning Cardiac Analysis in Mice with Cardiomyopathy

Accurate assessment of left ventricular function in rodent models is essential for the evaluation of new therapeutic approaches for cardiac diseases. In our study, we provide new insights regarding the role of a 1.5 Tesla (T) magnetic resonance imaging (MRI) device and different anesthetic regimens on data validity. As dedicated small animal MRI and echocardiographic devices are not broadly available, we evaluated whether monitoring cardiac function in small rodents with a clinical 1.5 T MRI device is feasible. On a clinical electrocardiogram (ECG) synchronized 1.5 T MRI scanner we therefore studied cardiac function parameters of mice with chronic virus-induced cardiomyopathy. Thus, reduced left ventricular ejection fraction (LVEF) could be verified compared to healthy controls. However, our results showed a high variability. First, anesthesia with medetomidine, midazolam and fentanyl (MMF) led to depressed cardiac function parameters and more variability than isoflurane gas inhalation anesthesia, especially at high concentrations. Furthermore, calculation of an average ejection fraction value from sequenced scans significantly reduced the variance of the results. To sum up, we introduce the clinical 1.5 T MRI device as a new tool for effective analysis of left ventricular function in mice with cardiomyopathy. Besides, we suggest isoflurane gas inhalation anesthesia at high concentrations for variance reduction and recommend calculation of an average ejection fraction value from multiple sequenced MRI scans to provide valid data and a solid basis for further clinical testing.     

Analysis of right ventricular function in healthy mice and a murine model of heart failure by in vivo MRI

Because of its complex geometry, assessment of right ventricular (RV) function is more difficult than it is for the left ventricle (LV). Because gene-targeted mouse models of cardiomyopathy may involve remodeling of the right heart, the purpose of this study was to develop high-resolution functional magnetic resonance imaging (MRI) for in vivo quantification of RV volumes and global function in mice. Thirty-three mice of various age were studied under isoflurane anesthesia by electrocardiogram-triggered cine-MRI at 7 T. MRI revealed close correlations between RV and LV stroke volume and cardiac output (r = 0.97, P < 0.0001 each). Consistent with human physiology, murine RV end-diastolic and end-systolic volumes were significantly higher compared with LV volumes (P < 0.05 each). MRI in mice with LV heart failure due to myocardial infarction revealed significant structural and functional changes of the RV, indicating RV dysfunction. Hence, MRI allows for the quantification of RV volumes and global systolic function with high accuracy and bears the potential to evaluate mechanisms of RV remodeling in mouse models of heart failure.     

Medium-term cardiovascular effects of high-dose growth hormone treatment in growth hormone-deficient children

AIM: To investigate the possible cardiac morphofunctional alterations inducd by prolonged and high-dose GH therapy in a group of 14 children with isolated GH deficiency. PATIENTS AND METHODS: Patients were evaluated at phase 1, after 1.1 +/- 0.6 years of treatment with GH 0.93 +/- 0.13 U/kg/week, and at phase 2, after 5.5 +/- 2.1 years of therapy 0.89 +/- 0.11 U/kg/week. At each phase left ventricular volume, mass and systolic function were evaluated by two-dimensional guided M-mode echocardiography; left ventricular diastolic function was assessed by PW-Doppler sampling of transmitral flow. RESULTS: Phase 1: diastolic blood pressure was lower (p < 0.05) and fractional shortening was not adequate for the level of afterload (stress shortening index p < 0.05) in patients compared to controls. Phase 2: diastolic blood pressure was lower (p < 0.01) and mass and mass/volume ratio were increased (mass index p < 0.05, mass/ volume ratio p < 0.05) in patients compared to controls. The increased mass/volume ratio, together with the normal systolic blood pressure, explains the reduction in peak systolic stress (p < 0.005). Among the parameters of left ventricular diastolic function, the peak E velocity/total area under mitral valve tracing and the area under E velocity/total area under mitral value tracing ratios were significantly decreased (p < 0.05). CONCLUSION: After a mean period of 5 years on high-dose GH treatment in GH-deficient children, subclinical morphofunctional alterations in the left ventricle were found.     

Heart size-independent analysis of myocardial function in murine pressure overload hypertrophy

Pressure overload cardiac hypertrophy may be a compensatory mechanism to normalize systolic wall stress and preserve left ventricular (LV) function. To test this concept, we developed a novel in vivo method to measure myocardial stress (sigma)-strain (epsilon) relations in normal and hypertrophied mice. LV volume was measured using two pairs of miniature omnidirectional piezoelectric crystals implanted orthogonally in the endocardium and one crystal placed on the anterior free wall to measure instantaneous wall thickness. Highly linear sigma-epsilon relations were obtained in control (n = 7) and hypertrophied mice produced by 7 days of transverse aortic constriction (TAC; n = 13). Administration of dobutamine in control mice significantly increased the load-independent measure of LV contractility, systolic myocardial stiffness. In TAC mice, systolic myocardial stiffness was significantly greater than in control mice (3,156 +/- 1,433 vs. 1,435 +/- 467 g/cm(2), P < 0.01), indicating enhanced myocardial contractility with pressure overload. However, despite the increased systolic performance, both active (time constant of LV pressure decay) and passive (diastolic myocardial stiffness constant) diastolic properties were markedly abnormal in TAC mice compared with control mice. These data suggest that the development of cardiac hypertrophy is associated with a heightened contractile state, perhaps as an early compensatory response to pressure overload.     

不同剂量胺碘酮联合氯沙坦治疗阵发性房颤患者的临床研究

目的:通过探讨不同剂量胺碘酮联合氯沙坦治疗阵发性房颤(PAF)患者的临床疗效,为PAF的治疗提供参考。方法:选择2013年6月~2014年6月本院收治的PAF患者共84例,按照随机数字表法随机分为大剂量组和小剂量组,分别在治疗1、3、6、12个月后观察两组患者窦性心律维持效果、左心室功能和血清高敏C反应蛋白(Hs-CRP)水平。结果:治疗1个月后,两组患者窦性心律维持效果的总有效率分别为93.73%和90.00%,差异无统计学意义(x~2=2.235;P0.05)。治疗3、6和12个月后,小剂量组患者窦性心律维持有效率均高于大剂量组,差异有统计学意义(x~2=4.208、5.271、5.688;P0.05)。小剂量组患者最大P波时限(Pmax)、P波离散度(Pd)和左心房直径(LAD)值均显著低于大剂量组患者,差异有统计学意义(t=-6.071、-3.509、-3.998;P0.05);左心室射血分数(LVEF)值显著高于大剂量组患者,差异有统计学意义(t=3.935;P0.05)。治疗1、6和12个月后,小剂量组血清Hs-CRP水平均低于大剂量组,差异有统计学意义(t=-4.515、-10.431、-19.113;P0.05)。结论:小剂量胺碘酮联合氯沙坦能够有效提高阵发性房颤患者窦性心律维持效果,改善患者左心室功能,降低Hs-CRP水平,值得临床推广借鉴。     

Cardiomyogenic differentiation-independent improvement of cardiac function by human cardiomyocyte progenitor cell injection in ischaemic mouse hearts

We previously showed that human cardiomyocyte progenitor cells (hCMPCs) injected after myocardial infarction (MI) had differentiated into cardiomyocytes in vivo 3 months after MI. Here, we investigated the short-term (2 weeks) effects of hCMPCs on the infarcted mouse myocardium. MI was induced in immunocompromised (NOD/scid) mice, immediately followed by intramyocardial injection of hCMPCs labelled with enhanced green fluorescent protein (hCMPC group) or vehicle only (control group). Sham-operated mice served as reference. Cardiac performance was measured 2 and 14 days after MI by magnetic resonance imaging at 9.4 T. Left ventricular (LV) pressure-volume measurements were performed at day 15 followed by extensive immunohistological analysis. Animals injected with hCMPCs demonstrated a higher LV ejection fraction, lower LV end-systolic volume and smaller relaxation time constant than control animals 14 days after MI. hCMPCs engrafted in the infarcted myocardium, did not differentiate into cardiomyocytes, but increased vascular density and proliferation rate in the infarcted and border zone area of the hCMPC group. Injected hCMPCs engraft into murine infarcted myocardium where they improve LV systolic function and attenuate the ventricular remodelling process 2 weeks after MI. Since no cardiac differentiation of hCMPCs was evident after 2 weeks, the observed beneficial effects were most likely mediated by paracrine factors, targeting amongst others vascular homeostasis. These results demonstrate that hCMPCs can be applied to repair infarcted myocardium without the need to undergo differentiation into cardiomyocytes.     

Cardiac-restricted expression of the carboxyl-terminal fragment of GRK3 Uncovers Distinct Functions of GRK3 in regulation of cardiac contractility and growth: GRK3 controls cardiac alpha1-adrenergic receptor responsiveness

G protein-coupled receptor kinase-2 and -3 (GRK2 and GRK3) in cardiac myocytes catalyze phosphorylation and desensitization of different G protein-coupled receptors through specificity controlled by their carboxyl-terminal pleckstrin homology domain. Although GRK2 has been extensively investigated, the function of cardiac GRK3 remains unknown. Thus, in this study cardiac function of GRK3 was investigated in transgenic (Tg) mice with cardiac-restricted expression of a competitive inhibitor of GRK3, i.e. the carboxyl-terminal plasma membrane targeting domain of GRK3 (GRK3ct). Cardiac myocytes from Tg-GRK3ct mice displayed significantly enhanced agonist-stimulated alpha(1)-adrenergic receptor-mediated activation of ERK1/2 versus cardiac myocytes from nontransgenic littermate control (NLC) mice consistent with inhibition of GRK3. Tg-GRK3ct mice did not display alterations of cardiac mass or left ventricular dimensions compared with NLC mice. Tail-cuff plethysmography of 3- and 9-month-old mice revealed elevated systolic blood pressure in Tg-GRK3ct mice versus control mice (3-month-old mice, 136.8 +/- 3.6 versus 118.3 +/- 4.7 mm Hg, p < 0.001), an observation confirmed by radiotelemetric recording of blood pressure of conscious, unrestrained mice. Simultaneous recording of left ventricular pressure and volume in vivo by miniaturized conductance micromanometry revealed increased systolic performance with significantly higher stroke volume and stroke work in Tg-GRK3ct mice than in NLC mice. This phenotype was corroborated in electrically paced ex vivo perfused working hearts. However, analysis of left ventricular function ex vivo as a function of increasing filling pressure disclosed significantly reduced (dP/dt)(min) and prolonged time constant of relaxation (tau) in Tg-GRK3ct hearts at elevated supraphysiological filling pressure compared with control hearts. Thus, inhibition of GRK3 apparently reduces tolerance to elevation of preload. In conclusion, inhibition of cardiac GRK3 causes hypertension because of hyperkinetic myocardium and increased cardiac output relying at least partially on cardiac myocyte alpha(1)-adrenergic receptor hyper-responsiveness. The reduced tolerance to elevation of preload may cause impaired ability to withstand pathophysiological mechanisms of heart failure.     

Cardiac performance in Turner's syndrome patients on growth hormone therapy.

OBJECTIVES: To investigate possible cardiac morphofunctional alterations observed in 26 Turner's syndrome (TS) patients on prolonged high-dose growth hormone (GH) therapy. STUDY DESIGN: We examined 26 TS subjects treated with rhGH (1 U/kg/week) for a mean period of 4.9 years (range 1-7.8) and 37 age-, weight- and height-matched healthy girls. Left ventricular volume, mass, systolic function, cardiac index, systemic vascular resistance and diastolic function were evaluated by two-dimensional and Doppler echocardiography. RESULTS: Heart rate and systolic blood pressure (BP) were higher in TS patients than in controls, while diastolic BP was lower. Left ventricular volumes, ejection fraction, mass index, M/V ratio and cardiac index did not differ significantly; systemic vascular resistance was slightly decreased. Left ventricular fractional shortening and mean velocity of circumferential shortening were slightly increased while end-systolic meridional stress was decreased in TS. Contractile state was normal in TS. Diastolic function assessment showed a shortening of isovolumetric relaxation and diastolic filling times with an increased atrial contribution and a normal pulmonary venous flow. CONCLUSION: Cardiac morphology in TS patients on GH therapy is similar to controls. The observed changes in left ventricular systolic and diastolic function should be interpreted as an adaptation to the higher heart rate and reduced peripheral vascular resistance induced by GH therapy.     

Rapid microcomputed tomography suggests cardiac enlargement occurs during conductance catheter measurements in mice

Conductance catheters (CC) represent an established method of determining cardiac function in mice; however, the potentially detrimental effects a catheter may have on the mouse heart have never been evaluated. The present study takes advantage of rapid three-dimensional (3D) microcomputed tomography (CT) to compare simultaneously acquired micro-CT and CC measurements of left ventricular (LV) volumes in healthy and infarcted mice and to determine changes in LV volume and function associated with CC insertion. LV volumes were measured in C57BL/6 mice (10 healthy, 10 infarcted, 2% isoflurane anesthesia) using a 1.4-Fr Millar CC. 3D micro-CT images of each mouse were acquired before CC insertion as well as during catheterization. Each CT scan produced high-resolution images throughout the entire cardiac cycle in <1 min, enabling accurate volume measurements as well as direct visualization of the CC within the LV. Bland-Altman analysis demonstrated that CC measurements underestimate volume compared with CT measurements in both healthy [bias of -18.4 and -28.9 μl for end-systolic (ESV) and end-diastolic volume (EDV), respectively] and infarcted mice (ESV = -51.6 μl and EDV = -71.7 μl); underestimation was attributed to the off-center placement of the catheter. Individual evaluation of each heart revealed LV dilation following CC insertion in 40% of mice in each group. No change in ejection fraction was observed, suggesting the enlargement was caused by volume overload associated with disruption of the papillary muscles or chords. The enlargement witnessed was not significant; however, the results suggest the potential for CC insertion to detrimentally affect mouse myocardium, necessitating further investigation.     

MicroRNA-1 transfected embryonic stem cells enhance cardiac myocyte differentiation and inhibit apoptosis by modulating the PTEN/Akt pathway in the infarcted heart

microRNAs (miRs) have emerged as critical modulators of various physiological processes including stem cell differentiation. Indeed, miR-1 has been reported to play an integral role in the regulation of cardiac muscle progenitor cell differentiation. However, whether overexpression of miR-1 in embryonic stem (ES) cells (miR-1-ES cells) will enhance cardiac myocyte differentiation following transplantation into the infarcted myocardium is unknown. In the present study, myocardial infarction (MI) was produced in C57BL/6 mice by left anterior descending artery ligation. miR-1-ES cells, ES cells, or culture medium (control) was transplanted into the border zone of the infarcted heart, and 2 wk post-MI, cardiac myocyte differentiation, adverse ventricular remodeling, and cardiac function were assessed. We provide evidence demonstrating enhanced cardiac myocyte commitment of transplanted miR-1-ES cells in the mouse infarcted heart as compared with ES cells. Assessment of apoptosis revealed that overexpression of miR-1 in transplanted ES cells protected host myocardium from MI-induced apoptosis through activation of p-AKT and inhibition of caspase-3, phosphatase and tensin homolog, and superoxide production. A significant reduction in interstitial and vascular fibrosis was quantified in miR-1-ES cell and ES cell transplanted groups compared with control MI. However, no statistical significance between miR-1-ES cell and ES cell groups was observed. Finally, mice receiving miR-1-ES cell transplantation post-MI had significantly improved heart function compared with respective controls (P < 0.05). Our data suggest miR-1 drives cardiac myocyte differentiation from transplanted ES cells and inhibits apoptosis post-MI, ultimately giving rise to enhanced cardiac repair, regeneration, and function.     

不同程度内质网应激对ApoE-/- 小鼠动脉粥样硬化斑块稳定性的影响

目的:采用Apo E-/-小鼠建立不稳定动脉粥样硬化斑块模型,给予不同剂量衣霉素,观察其对动脉粥样硬化斑块稳定性的影响。方法:取40只6-8周的Apo E-/-小鼠随机分为对照组和手术组。对照组小鼠给予正常饮食;手术组小鼠行右侧颈总动脉套管术(Perivascular carotid collar placement,PCCP),同时给予高脂喂养。9周末分别取对照组和手术组小鼠颈动脉,HE染色观察小鼠颈动脉斑块形成情况。成功造模后,将小鼠随机分为正常对照组、单纯PCCP组、小剂量衣霉素组和大剂量衣霉素组;正常对照组和单纯PCCP组给予生理盐水腹腔注射,小剂量衣霉素组和大剂量衣霉素组分别给予小剂量衣霉素、大剂量衣霉素腹腔注射。2周后,处死小鼠,通过HE染色观察颈动脉斑块形态,油红O染色观察斑块内脂质聚集,抗巨噬细胞免疫组化染色观察斑块内巨噬细胞聚集,Western-blot检内质网应激标志蛋白GRP78和自噬标志蛋白Atg7、P62的表达水平。结果:HE染色结果显示:与单纯PCCP组和大剂量衣霉素组相比,小剂量衣霉素组颈动脉腔内的斑块脂质池减少,斑块结构较为完整且相对稳定;油红O染色结果显示:小剂量衣霉素组斑块内脂质含量显著降低(P0.05 vs单纯PCCP组和大剂量衣霉素组);巨噬细胞免疫组化染色显示:与单纯PCCP组和大剂量衣霉素组相比,小剂量衣霉素组斑块内巨噬细胞的含量显著降低(P0.05);Western-blot结果显示:小剂量衣霉素干预诱导的一定程度的内质网应激可以适度上调自噬(P0.05 vs单纯PCCP组和大剂量衣霉素组)。结论:PCCP手术加高脂饮食可以短期成功建立小鼠不稳定动脉粥样硬化斑块模型,其动脉粥样硬化斑块不稳定性较高,而小剂量衣霉素干预可以使得颈动脉管腔内斑块相对较小,内部脂质池明显较小,纤维帽变厚且结构更完整,斑块结构较稳定;斑块内脂质含量降低;巨噬细胞含量明显降低,且小剂量衣霉素组自噬水平适度上调。因此,小剂量衣霉素干预引起的适度的内质网应激一定程度对动脉粥样硬化斑块起到保护作用。     

不同鼠龄的人多巴胺D5^F173L突变基因转基因高血压小鼠血压及心脏结构与功能分析

目的通过对不同年龄多巴胺D5^F173L突变基因及D5正常基因转基因小鼠的血压和心脏结构与功能进行分析,了解多巴胺D5受体在高血压发生发展过程中的作用。方法利用无创血压测量仪和高分辨率小动物超声系统检测两种转基因小鼠的血压和左心室壁厚度、左心室内径、左心室容积、射血分数、短轴缩短率和左心室质量等心脏功能指标。结果 D5^F173L转基因小鼠4月龄、6月龄、16月龄时收缩压、舒张压都明显高于D5转基因小鼠;4月龄、6月龄的D5F173L转基因小鼠与D5转基因小鼠相比舒张期和收缩期左室壁厚度均明显增大、左室内容积均明显变小、左心室重量增加;16月龄的D5^F173L转基因小鼠与D5转基因小鼠相比左心室前壁增厚、心腔内径缩短,心腔容积下降、心室重量增加、射血分数提高、短轴缩短率提高;在18月龄时D5^F173L转基因小鼠相比于D5转基因小鼠左心室收缩期前壁厚度增加,后壁厚度减少,舒张期前壁厚度增加,后壁厚度减少;另外在18月龄时D5^F173L转基因小鼠与其16月龄时相比,射血分数、短轴缩短率明显降低,收缩期左心室容积明显增大。结论 D5^F173L转基因小鼠的血压及心脏功能与结构的分析结果符合原发性高血压的特征。D5^F173L转基因小鼠可作为原发性高血压动物模型。     

Ventricular function during exercise in mice and rats

The mouse has many advantages over other experimental models for the molecular investigation of left ventricular (LV) function. Accordingly, there is a keen interest in, as well as an intense need for, a conscious, chronically instrumented, freely moving mouse model for the determination of cardiac function. To address this need, we used a telemetry device for repeated measurements of LV function in conscious mice at rest and during exercise. For reference, we compared the responses in mice to the responses in identically instrumented conscious rats. The transmitter body of the telemetry device (rat PA-C40; mouse PA-C10; Data Sciences International, St. Paul, MN) was placed in the intraperitoneal space through a ventral abdominal approach (rat) or subcutaneously on the left flank (mouse). The pressure sensor, located within the tip of a catheter, was inserted into the left ventricle through an apical stab wound (18 gauge for rat; 21 gauge for mouse) for continuous, nontethered, recordings of pulsatile LV pressure. A minimum of 1 wk was allowed for recovery and for the animals to regain their presurgical weight. During the recovery period, the animals were handled, weighed, and acclimatized to the laboratory, treadmill, and investigators. Subsequently, LV parameters were recorded at rest and during a graded exercise test. The results document, for the first time, serial assessment of ventricular function during exercise in conscious mice and rats. This methodology may be adopted for advancing the concepts and ideas that drive cardiovascular research.     

Cardiac matrix metalloproteinase-2 expression independently induces marked ventricular remodeling and systolic dysfunction

Although enhanced cardiac matrix metalloproteinase (MMP)-2 synthesis has been associated with ventricular remodeling and failure, whether MMP-2 expression is a direct mediator of this process is unknown. We generated transgenic mice expressing active MMP-2 driven by the alpha-myosin heavy chain promoter. At 4 mo MMP-2 transgenic hearts demonstrated expression of the MMP-2 transgene, myocyte hypertrophy, breakdown of Z-band registration, lysis of myofilaments, disruption of sarcomere and mitochondrial architecture, and cardiac fibroblast proliferation. Hearts from 8-mo-old transgenic mice displayed extensive myocyte disorganization and dropout with replacement fibrosis and perivascular fibrosis. Older transgenic mice also exhibited a massive increase in cardiac MMP-2 expression, representing recruitment of endogenous MMP-2 synthesis, with associated expression of MMP-9 and membrane type 1 MMP. Increases in diastolic [control (C) 33 +/- 3 vs. MMP 51 +/- 12 microl; P = 0.003] and systolic (C 7 +/- 2 vs. MMP 28 +/- 14 microl; P = 0.003) left ventricular (LV) volumes and relatively preserved stroke volume (C 26 +/- 4 vs. MMP 23 +/- 3 microl; P = 0.16) resulted in markedly decreased LV ejection fraction (C 78 +/- 7% vs. MMP 48 +/- 16%; P = 0.0006). Markedly impaired systolic function in the MMP transgenic mice was demonstrated in the reduced preload-adjusted maximal power (C 240 +/- 84 vs. MMP 78 +/- 49 mW/microl(2); P = 0.0003) and decreased end-systolic pressure-volume relation (C 7.5 +/- 1.5 vs. MMP 4.7 +/- 2.0; P = 0.016). Expression of active MMP-2 is sufficient to induce severe ventricular remodeling and systolic dysfunction in the absence of superimposed injury.