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1.
探究不同粒径(50 nm、200 nm和1 000 nm)、浓度(清水组、低浓度组、中浓度组和高浓度组)荧光聚苯乙烯微球溶液组合对37期黑斑侧褶蛙(Pelophylax nigromaculatus)蝌蚪身体大小和脏器系数的影响,连续测定了暴露7 d时,之后清水清除饲养7 d(14 d时)和14 d(21 d时),其体重与体全长的比值(重长比)、小肠长度以及心、肝湿重的变化。重长比在200 nm粒径条件下不受聚苯乙烯微球暴露和清除影响(P > 0.05);50 nm清水组14 d时低于其他浓度组(P < 0.05);1 000 nm中浓度组7 d时和14 d时高于21 d时(P < 0.05),7 d时高浓度组低于其他浓度组(P < 0.05),21 d时清水组和低浓度组都高于中浓度组(P < 0.05)。小肠长度系数在200 nm高浓度组随时间而变化,7 d时至14 d时显著增加,21 d时陡降(P < 0.05),1 000 nm中浓度组7 d时和14 d时都显著高于21 d时(P < 0.05);7 d时,1 000 nm高浓度组显著低于其他浓度组(P < 0.05),50 nm、200 nm均无组间差异(P > 0.05)。心、肝湿重系数均不随处理时间而变化(P > 0.05);心湿重系数只在50 nm 14 d时变化显著,清水组最高,高、中浓度组其次,低浓度组最低(P < 0.05),肝湿重系数只在50 nm和200 nm 14 d时清水组低于其他浓度组(P < 0.05)。50 nm、200 nm和1 000 nm处理分别影响重长比、心和肝湿重系数,小肠长度系数和肝湿重系数,以及重长比和小肠长度系数,但与粒径和浓度均不呈线性关系。  相似文献   

2.
王锦蛇血清对尖吻蝮蛇毒的抑制作用   总被引:1,自引:1,他引:0  
黄松  黄接棠 《蛇志》2005,17(4):237-240
目的 探讨王锦蛇血清对尖吻蝮蛇毒的抑制作用。方法 王锦蛇血清与不同剂量的尖吻蝮蛇毒分别混合后,注射到小鼠背皮下,测定王锦蛇血清对尖吻蝮蛇毒的抗出血活力;腹腔注射此混合物后,测定王锦蛇血清对尖吻蝮蛇毒的抗毒效价;先后注射尖吻蝮蛇毒和王锦蛇血清,测定王锦蛇血清对尖吻蝮蛇毒引起的死亡、组织损伤和炎症的抑制、保护和治疗作用。结果 1ml王锦蛇血清可完全抑制10mg(干重)的尖吻蝮蛇毒的出血活力;1ml王锦蛇血清可中和11mg(干重)尖吻蝮蛇毒的致死活力;王锦蛇血清对由尖吻蝮蛇毒引起的致死、组织损伤和炎症有显著的抑制、保护和治疗作用。结论 王锦蛇血清是尖吻蝮蛇毒的强抑制剂,可能成为未来新的蛇伤治疗药物的原料。  相似文献   

3.
为了探讨不同日龄幼龄红嘴相思鸟(Leiothrix lutea)小脑皮质的组织学结构变化,本文分别以1、5、9日龄幼龄红嘴相思鸟为研究对象,通过H.E.和甲苯胺蓝法进行染色,光镜下观察红嘴相思鸟小脑冠状切面的显微结构。结果显示,1日龄时小脑皮层由外颗粒层(EGL)、浦肯野细胞层(PCL)和内颗粒层(IGL)3层构成,外颗粒层较厚且清晰,而浦肯野细胞层和内颗粒层界限不清楚;5日龄和9日龄时小脑皮质均可见外颗粒层、分子层(ML)、浦肯野细胞层和内颗粒层4层结构。对不同日龄红嘴相思鸟小脑皮质各层厚度进行单因素方差分析显示,随日龄增长,小脑皮质、分子层和内颗粒层厚度极显著增厚(P < 0.01),浦肯野细胞体积也极显著增加(P < 0.01);外颗粒层厚度变化不明显(P < 0.01),呈现先增厚后变薄的趋势,与皮质厚度的比例逐渐减小。研究表明,幼龄红嘴相思鸟在出生后,随日龄增长,小脑皮质层逐渐发育成熟。内颗粒层与外颗粒层的相对变化规律表明内颗粒层细胞是由外颗粒层细胞迁移而来。  相似文献   

4.
【目的】本文旨在探究意大利蜜蜂Apis mellifera ligustica幼虫饲粮中添加叶酸对雌性蜜蜂DNA甲基化及发育的影响。【方法】从姊妹蜂群中选用2日龄意大利蜜蜂雌性幼虫,平均分为6组,任选一组以饲喂不添加叶酸的基础日粮为对照组(CK),其余5组为试验组,分别饲喂添加0.02%、0.04%、0.06%、0.08%和0.10%叶酸的基础日粮。在室内温度(34.5±0.5)℃,相对湿度为90%±5%的条件下,按照饲养流程饲养意大利蜜蜂至出房。取3-5日龄的幼虫,测定叶酸代谢指标及DNA甲基化相关指标,计算新蜂发育历期,称量新蜂重。【结果】(1)添加叶酸(FA)水平为0.04%的试验组,3、4和5日龄幼虫蜂体内叶酸(FA)和5-甲基四氢叶酸(5-MTHF)含量显著高于对照组(P <0.05),并且显著提高了幼虫时期蜂体的二氢叶酸还原酶(DHFR)基因、丝氨酸羟甲基转移酶(SHMT)基因和亚甲基四氢叶酸还原酶(MTHFR)基因的表达量(P <0.05),显著提高了MTHFR酶活性(P <0.05)。(2)与对照组相比,添加叶酸为0.04%的试验组显著提高了3日龄幼虫DNA甲基转移酶1a(Dnmt1a)基因的表达量(P <0.05),且显著提高了3日龄和4日龄幼虫的DNA甲基转移酶1(DNMT1)酶活性(P <0.05)。添加0.04%的叶酸试验组相较于对照组显著降低了3日龄幼虫DNA甲基转移酶3(DNMT3)的酶活性(P <0.05),显著降低了4日龄幼虫Dnmt3基因的表达量和DNMT3酶活性(P <0.05)。叶酸添加剂量为0.04%时,4日龄蜂体DNA甲基化水平显著降低(P <0.05)。(3)与对照组相比,添加0.04%的叶酸试验组的意大利蜜蜂平均发育历期(19.95 d)显著小于对照组(P <0.05),平均新蜂重(0.17 g)显著大于对照组(P <0.05)。【结论】在基础日粮中添加适量叶酸能够降低4日龄意大利蜜蜂幼虫的DNA甲基化水平,并能缩短发育历期和增加新蜂重。在饲粮中添加0.04%的叶酸有助于雌性意大利蜜蜂幼虫向蜂王方向发育。  相似文献   

5.
血细胞是临床健康的重要指标。本文对北京海洋馆养殖的40尾中华鲟(Acipenser sinensis)外周血细胞组成进行研究,研究对象包括超过30龄、18龄、16龄、15龄、11龄、7龄和4龄共7个龄组,并分析比较不同年龄、性腺快速发育前后以及处于疾病前后血细胞指标变化,希望应用于健康评价。结果表明,1)外周血红细胞总数(RBC)平均为(5.56 ± 1.19)× 1011/L,18龄和11龄与其他龄组之间存在显著性差异(P < 0.05),超过30龄组血细胞比积(HCT)和血红蛋白(HB)值显著高于其他龄组(P < 0.05);2)白细胞总数(WBC)平均为(16.53 ± 4.94)× 109/L,18龄与4龄间存在显著差异,且分别与其他龄组间存在显著性差异(P < 0.05)。3)白细胞分类计数(DLC)中各类型白细胞平均所占百分比分别为,大淋巴细胞(LLYM)5.26% ± 3.95%、小淋巴细胞(SLYM)77.74% ± 11.73%、嗜中性粒细胞(NEU)9.40% ± 7.98%、嗜酸性粒细胞(EOS)1.90% ± 2.06%和单核细胞(MON)5.50% ± 4.00%,超过30龄和4龄间显著差异,且分别与其他龄组间存在显著性差异(P < 0.05)。4)性腺进入快速发育阶段后,红细胞总数、血细胞比积和白细胞总数较发育前均显著增加(P < 0.05),血红蛋白值有增加但差异不显著。5)疾病中华鲟白细胞总数显著增高(P < 0.05)并伴随红细胞各指标降低,白细胞数增加幅度达90%,分类计数中中性粒细胞和单核细胞比例显著变化(P < 0.05)。中华鲟快速发育阶段及疾病状态的血细胞组成不同,血细胞密度的变化以及分类计数的差异可及时判断中华鲟健康状况,结果对中华鲟的健康评价与保育研究有重要的参考意义。  相似文献   

6.
目的通过研究大豆异黄酮对雌鼠初情期等生殖性状的影响,为母鼠的安全饲喂提供实验依据。方法本实验选用210只21日龄ICR雌鼠随机分成3组,饲喂含不同浓度大豆异黄酮(0 mg/kg、50 mg/kg、400 mg/kg)的饲料。每日检查母鼠阴道开张和阴道栓情况。采集母鼠45和65日龄时血清,利用ELISA方法检测血清中雌激素含量,并统计45、65日龄体重和子宫重。利用免疫组织化学方法检测子宫上皮雌激素受体的表达分布情况。结果雌鼠阴道开张的平均日龄分别为27.2 d、26.1 d和25.8 d,400 mg/kg组显著早于剂量为0mg/kg的对照组(P〈0.05);雌鼠平均初次配种时间各组间差异不显著(P〉0.05);饲养到45日龄和65日龄时400 mg/kg组雌鼠体重显著高于对照组(P〈0.05)。喂养8周后两个试验组在子宫间质细胞上雌激素受体的阳性细胞表达率显著高于对照组;在腺上皮中400 mg/kg组显著高于50 mg/kg组和对照组(0 mg/kg);但是在腔上皮中,各组间受体的阳性细胞表达率差异不显著(P〉0.05)。结论饲喂每公斤含400 mg大豆异黄酮的饲料可以刺激初情期前母鼠阴道的开张,提高雌鼠的体重,降低65日龄时血清雌激素含量,并在饲喂8周后影响子宫间质和腺上皮上雌激素受体的表达分布;而饲喂每公斤含50 mg大豆异黄酮的饲料仅对小鼠45日龄体重及饲喂8周后子宫间质上雌激素受体的表达分布有所影响。  相似文献   

7.
王锦蛇消化道5-羟色胺细胞的免疫组织化学定位   总被引:2,自引:0,他引:2  
应用抗生物素蛋白-生物素-过氧化物酶复合物(Avidin-biotin-peroxidase complex,ABC)免疫组织化学方法对王锦蛇(Elaphe carinata)消化道5-羟色胺(5-hydroxytryptamine,5-HT)细胞的分布密度进行了观察。5-HT细胞在胃幽门部最高,胃体和十二指肠其次,食道、空肠和直肠最低。王锦蛇5-HT细胞的分布特点可能与其食性和生活环境有关。  相似文献   

8.
为了探讨藏山羊(Capra hircus)与藏绵羊(Ovis aries)在高原低氧环境中肺组织结构的差异,采用Gomori醛品红染色及H.E染色对藏山羊和藏绵羊肺组织进行对比研究。结果表明,藏山羊与藏绵羊肺被膜厚度无显著差异(P > 0.05),但肺被膜中弹力纤维藏山羊显著多于藏绵羊(P < 0.05)。肺泡面积藏山羊与藏绵羊无显著差异(P > 0.05),但肺泡隔宽度和肺泡隔中毛细血管的数量藏山羊显著高于藏绵羊(P < 0.05)。肺细支气管黏膜皱襞厚度藏山羊与藏绵羊无显著差异(P > 0.05),但细支气管平滑肌厚度藏山羊显著高于藏绵羊,细支气管黏膜上皮1 mm2中杯状细胞数量藏山羊显著高于藏绵羊(P < 0.05)。外径小于100 μm的肺微动脉中,藏山羊血管平滑肌占外径百分比显著高于藏绵羊(P < 0.05),而当外径大于100 μm时,两者间差异不显著(P > 0.05)。  相似文献   

9.
选取不同日龄的雄性哈萨克羊和新疆细毛羊,屠宰后取背最长肌,用索氏抽提法检测肌内脂肪(Intamuscular fat,IMF)含量,用荧光实时定量PCR法检测心脏脂肪酸结合蛋白(heart fatty acid-binding protein,H-FABP)和过氧化物酶体增殖物激活受体γ(peroxisome proliferator-activated receptorγ,PPARγ)基因表达的发育性变化极其对IMF含量的影响.结果表明:(1)随着日龄的增加,IMF含量在雄性哈萨克羊中持续上升,且在各生长期间的差异显著(P<0.05),而在新疆细毛羊的各生长期间无显著差异(P>0.05).雄性哈萨克羊的IMF含量在30~90日龄间极显著高于新疆细毛羊(P<0.01);(2)雄性哈萨克羊肌肉H-FABP基因的表达量在2日龄时最高,30日龄时降到最低,然后持续上升,各日龄间差异显著(P<0.05).新疆细毛羊中的表达量在2日龄时也最高,然后持续下降,到90日龄时降到了最低点,然后上升,各日龄间差异也显著(P<0.05);(3)雄性哈萨克羊肌肉PPARγ基因的表达量随着日龄的增加而呈下降趋势,各日龄间差异显著(P<0.05);新疆细毛羊中的表达量在2~60日龄期间持续上升且各日龄间差异显著(P<0.05),但在90日龄时降到最低点,然后上升;(4)在哈萨克羊中,H-FABP基因在30~90日龄间的表达量与IMF含量的相关系数为0.737(P<0.01),而PPARγ基因在2-90日龄间的表达量与之的相关系数为-0.835(P<0.01).  相似文献   

10.
摘要 目的:研究速度向量成像技术对肥厚型心肌病(HCM)左心室扭转功能和收缩功能的影响。方法:纳入我院从2018年1月~2019年1月收治的HCM患者30例进行研究,记作病变组,另取同期于我院进行体检的健康志愿者30例作为对照组。比较两组常规左心功能超声心动图指标、左室整体扭转和解旋运动指标、左室局部扭转和解旋运动指标、圆周应变以及应变率。结果:病变组舒张末期容积(EDV)、收缩末期容积(ESV)、每搏量(SV)均较对照组更低(P<0.05),而两组左室射血分数(LVEF)比较差异不显著(P>0.05)。病变组心内膜的左心室扭转角度(LVtw)以及左心室扭矩(LVtor)均显著高于对照组,而心内膜及心外膜解扭转率(UntwR)显著低于对照组(P<0.05)。病变组基底部心内膜旋转速率、心尖部心外膜旋转速率均显著低于对照组,心尖部心内膜旋转速率显著高于对照组,心尖部心外膜解旋速率显著高于对照组(P<0.05)。病变组基底部心内膜圆周应变低于对照组,基底部、心尖部心外膜圆周应变高于对照组(P<0.05);病变组基底部、心尖部心外膜应变率均高于对照组(P<0.05)。结论:HCM患者收缩功能降低,且局部心肌圆周方向的形变能力明显下降。  相似文献   

11.
Early relaxation in the cardiac cycle is characterized by rapid torsional recoil of the left ventricular (LV) wall. To elucidate the contribution of the transmural arrangement of the myofiber to relaxation, we determined the time course of three-dimensional fiber-sheet strains in the anterior wall of five adult mongrel dogs in vivo during early relaxation with biplane cineangiography (125 Hz) of implanted transmural markers. Fiber-sheet strains were found from transmural fiber and sheet orientations directly measured in the heart tissue. The strain time course was determined during early relaxation in the epicardial, midwall, and endocardial layers referenced to the end-diastolic configuration. During early relaxation, significant circumferential stretch, wall thinning, and in-plane and transverse shear were observed (P < 0.05). We also observed significant stretch along myofibers in the epicardial layers and sheet shortening and shear in the endocardial layers (P < 0.01). Importantly, predominant epicardial stretch along the fiber direction and endocardial sheet shortening occurred during isovolumic relaxation (P < 0.05). We conclude that the LV mechanics during early relaxation involves substantial deformation of fiber and sheet structures with significant transmural heterogeneity. Predominant epicardial stretch along myofibers during isovolumic relaxation appears to drive global torsional recoil to aid early diastolic filling.  相似文献   

12.
蒋福升  陈铌铍  丁滨 《蛇志》2014,(1):108-111
目的探讨发酵床模式养殖尖吻蝮、舟山眼镜蛇和王锦蛇的可行性。方法分别选取3种健康驯饲好的4月龄蛇苗,各分成2组,一组采用传统沙床饲养模式,另一组采用发酵床饲养模式,饲养8个月后,通过比较蛇的体重、料肉比及环境氨气浓度变化,分析发酵床养殖模式优劣。结果就尖吻蝮养殖效果而言,采用两种养殖模式无显著性差异;但采用发酵床模式对眼镜蛇和王锦蛇饲养相比沙床模式具有明显优势,表现为增重更快、料肉比更小,且氨气浓度显著降低;氨气浓度及体重变化分析结果表明,5ppm以上浓度对王锦蛇生长有一定影响,10ppm以上浓度对眼镜蛇生长有一定影响。结论发酵床技术可用于蛇类养殖,而且总体上优于传统沙床模式;此外,发酵床模式尤其适宜如眼镜蛇和王锦蛇等活动较多、进食量较大、排便量大的蛇类养殖。  相似文献   

13.
The purpose of this study was to determine the effects of exercise training on ventricular epicardial fat thickness in obese men and to investigate the relationship of the change in epicardial fat thickness to changes in abdominal fat tissue following exercise training. Twenty-four obese middle-aged men [age, 49.4 +/- 9.6 yr; weight, 87.7 +/- 11.2 kg; body mass index (BMI), 30.7 +/- 3.3 kg/m(2); peak oxygen consumption, 28.4 +/- 7.2 ml.kg(-1).min(-1); means +/- SD] participated in this study. Each participant completed a 12-wk supervised exercise training program (60-70% of the maximal heart rate; 60 min/day, 3 days/wk) and underwent a transthoracic echocardiography. The epicardial fat thickness on the free wall of the right ventricle was measured from both parasternal long- and short-axis views. The visceral adipose tissue (VAT) and subcutaneous adipose tissues were measured by computed tomography. Following exercise training, the epicardial fat thickness was significantly decreased (P < 0.001). The percentage change of epicardial fat thickness was twice as high compared with those of waist, BMI, and body weight of original values (P <0.05). There was a significant relationship (r = 0.525, P = 0.008) between changes in the epicardial fat thickness and VAT with exercise training. Stepwise multiple regression analysis revealed that the change in VAT, change in systolic blood pressure, and change in quantitative insulin sensitivity check index were independently related to the change epicardial fat thickness (P < 0.05). The ventricular epicardial fat thickness is reduced significantly after aerobic exercise training and is associated with a decrease in VAT. These results suggest that aerobic exercise training may be an effective nonpharmacological strategy for decreasing the ventricular epicardial fat thickness and visceral fat area in obese middle-aged men.  相似文献   

14.
To test the hypothesis that coronary flow and coronary flow reserve are developmentally regulated, we used fluorescent microspheres to investigate the effects of acute (6 h) pulmonary artery banding (PAB) on baseline and adenosine-enhanced right (RV) and left ventricular (LV) blood flow in two groups of twin ovine fetuses (100 and 128 days of gestation, term 145 days, n = 6 fetuses/group). Within each group, one fetus underwent PAB to constrict the main pulmonary artery diameter by 50%, and the other twin served as a nonbanded control. Physiological measurements were made 6 h after the surgery was completed; tissues were then harvested for analysis of selected genes that may be involved in the early phase of coronary vascular remodeling. Within each age group, arterial blood gas values, heart rate, and mean arterial blood pressure were similar between control and PAB fetuses. Baseline endocardial blood flow in both ventricles was greater in 100 than 128-day fetuses (RV: 341 +/- 20 vs. 230 +/- 17 ml*min(-1)*100 g(-1); LV: 258 +/- 18 vs. 172 +/- 23 ml*min(-1)*100 g(-1), both P < 0.05). In both age groups, RV and LV endocardial blood flows increased significantly in control animals during adenosine infusion and were greater in PAB compared with control fetuses. After PAB, adenosine further increased RV blood flow in 128-day fetuses (from 416 +/- 30 to 598 +/- 33 ml*min(-1)*g(-1), P < 0.05) but did not enhance blood flow in 100-day animals (490 +/- 59 to 545 +/- 42 ml*min(-1)*100 g(-1), P > 0.2). RV vascular endothelial growth factor and Flk-1 mRNA levels were increased relative to controls (P < 0.05) in 128 but not 100-day PAB fetuses. We conclude that in the ovine fetus, developmentally related differences exist in 1) baseline myocardial blood flows, 2) the adaptive response of myocardial blood flow to acute systolic pressure load, and 3) the responses of selected genes involved in vasculogenesis to increased load in the fetal myocardium.  相似文献   

15.
Cardiac resynchronization therapy (CRT) is a proven treatment for heart failure but ~30% of patients appear to not benefit from the therapy. Left ventricular (LV) endocardial and multisite epicardial [triventricular (TriV)] pacing have been proposed as alternatives to traditional LV transvenous epicardial pacing, but no study has directly compared the hemodynamic effects of these approaches. Left bundle branch block ablation and repeated microembolizations were performed in dogs to induce electrical dysynchrony and to reduce LV ejection fraction to <35%. LVdP/dt(max) and other hemodynamic indexes were measured with a conductance catheter during LV epicardial, LV endocardial, biventricular (BiV) epicardial, BiV endocardial, and TriV pacing performed at three atrioventricular delays. LV endocardial pacing was obtained with a clinically available pacing system. The optimal site was defined as the site that increased dP/dt(max) by the largest percentage. Implantation of the endocardial lead was feasible in all canines (n = 8) without increased mitral regurgitation seen with transesophageal echocardiography and with full access to the different LV endocardial pacing sites. BiV endocardial pacing increased dP/dt(max) more than BiV epicardial and TriV pacing on average (P < 0.01) and at the optimal site (P < 0.01). There were no significant differences between BiV epicardial and TriV pacing. BiV endocardial pacing was superior to BiV epicardial and to TriV pacing in terms of acute hemodynamic response. Further investigation is needed to confirm the chronic benefit of this approach in humans.  相似文献   

16.
The epicardium regulates growth and survival of the underlying myocardium. This activity depends on intrinsic retinoic acid (RA) and erythropoietin signals. However, these signals do not act directly on the myocardium and instead are proposed to regulate the production of an unidentified soluble epicardial derived mitogen. Here, we show that Fgf9, Fgf16, and Fgf20 are expressed in the endocardium and epicardium and that RA can induce epicardial expression of Fgf9. Using knockout mice and an embryonic heart organ culture system, we show that endocardial and epicardial derived FGF signals regulate myocardial proliferation during midgestation heart development. We further show that this FGF signal is received by both FGF receptors 1 and 2 acting redundantly in the cardiomyoblast. In the absence of this signal, premature differentiation results in cellular hypertrophy and newborn mice develop a dilated cardiomyopathy. FGFs thus constitute all or part of the epicardial signal regulating myocardial growth and differentiation.  相似文献   

17.
两栖动物的体重和内脏器官大小可随环境条件而变化,具有表型可塑性,但实验例证较少,尤其缺乏与可变的食物可利用性有关的研究。本研究以捕自安徽省定远县县郊的雌、雄中华蟾蜍(Bufo gargarizans)为研究对象,测定了自由取食组、禁食1周组、禁食2周组、重喂食1周组和重喂食2周组其体重、内脏器官湿重和干重的变化情况。1)中华蟾蜍的体重、胴体湿重和干重均无明显的性别(P0.05)和组间(P0.05)差异。2)雌蟾胃的湿重、干重和大肠湿重高于雄蟾(P0.05),其他内脏器官(小肠、胸腺、心、肝、肺、脂肪体、脾和肾)的湿重和干重均无性别差异(P0.05);雄蟾上述指标均无组间差异(P0.05);雌蟾的胃湿重和大肠湿重均无组间差异(P0.05),但胃干重自由取食组高于重喂食1周组(P0.05)。禁食2周组的小肠湿重下降,低于自由取食组、重喂食1周和2周组(P0.05)。3)禁食1周组的心湿重高于重喂食2周组(P0.05)。结果表明,中华蟾蜍在整体水平不受短期禁食和重喂食处理的影响,器官水平可能主要依赖适度饥饿而导致的心肌功能的提升和消化道的可塑性来应对变化的食物条件。  相似文献   

18.
A change in activation sequence electrically remodels ventricular myocardium, causing persistent changes in repolarizing currents (T-wave memory). However, the underlying mechanism for triggering activation sequence-dependent remodeling is unknown. Optical action potentials were mapped with high resolution from the epicardial surface of the arterially perfused canine wedge preparation (n = 23) during 30 min of baseline endocardial stimulation, followed by 40 min of epicardial stimulation, and, finally, restoration of endocardial stimulation. Immediately after the change from endocardial to epicardial stimulation, phase 1 notch amplitude of epicardial cells was attenuated by 74 +/- 8% (P < 0.001) compared with baseline and continued to diminish during the period of epicardial pacing, suggesting progressive remodeling of the transient outward current (Ito). When endocardial pacing was restored, notch amplitude did not immediately recover but remained attenuated by 23 +/- 10% (P < 0.001), also consistent with a remodeling effect. Peak Ito current measured from isolated epicardial myocytes changed by 12 +/- 4% (P < 0.025), providing direct evidence for Ito remodeling occurring on a surprisingly short time scale. The mechanism for triggering remodeling of Ito was a significant reduction (by 14 +/- 4%, P < 0.001) of upstroke amplitude in epicardial cells during epicardial stimulation. Reduction in upstroke amplitude during epicardial pacing was explained by electrotonic load on epicardial cells by fully repolarized downstream endocardial cells. These data suggest a novel mechanism for triggering electrical remodeling in the ventricle. Electrotonic load imposed by a change in activation sequence reduces upstroke amplitude, which, in turn, attenuates Ito according to its known voltage-dependent properties, triggering downregulation of current.  相似文献   

19.
The ultrastructure of the heart in 2 and 6 d old larvae of Melanogrammus aeglefinus and 1, 7, 14, and 21 d old larvae of Poecilia reticulata, is described. Additional studies were done on prenatal specimens of P. reticulata. In the atrium of M. aeglefinus the endocardium is separated from the muscle wall by a wide, electron lucent space, which probably contains cardiac jelly (Davis 1924). The myocardium is an 1 cell-thick layer in the atrium, whereas it consists of 2 to 4 cells in the ventricle. Cardiac trabeculae seem to be absent. The contractile material appears more developed at the endocardial side of the muscle wall than at the epicardial side. Thus, in the latter area the myofibrils are thin, few in number, and embedded in large amounts of free ribosomes. Often they radiate from a spot of electron dense material or an intercalated disc. Generally, intercalated discs, short nexuses and specific heart granules (Jamieson and Palade 1964) occur in ventricular as well as in atrial myocardial tissue. In P. reticulata cardiac jelly seems absent, whereas cardiac trabeculae occur regularly, particularly in the ventricle. The myofibrillar apparatus displays a nearly adult structure. However, in the ventricular wall, there occur spots and bands of intracellular, electron dense material at that sarcolemma facing the subepicardial space. Normally, myofibrils extend from this material into the cellular cytoplasm. Subsarcolemmal electron dense material was only scarcely seen in the atrial wall.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

20.
几种游蛇的Cyt b基因片段序列分析及其演化关系   总被引:5,自引:0,他引:5  
分别从蛇类药材和冷冻保存的新鲜蛇类肌肉标本中提取DNA,经PCR扩增出12种蛇共25个样品的Cyt b基因片段,并用银染测序的方法对DNA序列进行了分析.在此基础上用MEGA软件重建的系统发生树表明,研究的11种游蛇科蛇类可以分为3组:第一组为赤链蛇和水赤链游蛇,第二组为乌梢蛇和灰鼠蛇,第三组为锦蛇属的蛇,它们与第二组较近.锦蛇属是一高度分化的属,该组至少可分为两类,一类包括百花锦蛇和黑眉锦蛇;另一类包括玉斑锦蛇、棕黑锦蛇、红点锦蛇、王锦蛇和双斑锦蛇.后一类还可进一步分为3个亚组,玉斑锦蛇和棕黑锦蛇为第一亚组,红点锦蛇单独为第二亚组,王锦蛇和双斑锦蛇为第三亚组.本研究结果还表明,多年保存的陈旧药材标本可以用DNA序列分析的方法对其进行分子系统演化关系的研究.  相似文献   

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