人窦房结胶原纤维网架的构筑-NaOH蚀刻／扫描电镜观察

为研究人窦房结胶原纤维网架的三维构筑及其与窦房结中央动脉的关系，用NaOH销蚀法扫描电镜观察了11例成人窦房结。研究表明，成人窦房结的胶原纤维网架致密，窦房结中央动脉穿过结的中央或一侧。窦房结中央动脉的胶原纤维支架分为三层：在内膜呈网状；中膜的胶原纤维形成胶原纤维小梁，在中膜内层，胶原纤维小梁围绕窦房结中央动脉排列，在中膜外层，     

人窦房结胶原纤维比例与分型年龄变化的研究

目的：了解窦房结的胶原纤维年龄变化及分型。方法：采用Ｍａｓｓｏｎ三色染色网格测微器及苦味酸天狼猩红染色，分别作光镜、偏光显微镜观察，对４７例非心脏病变窦房结胶原纤维比例及分型进行检测。结果：窦房结胶原纤维随年龄的增高有增高的趋势，发现胶原纤维以１型为主，３型胶原纤维随年龄的增高有减少的趋势。结论：窦房结在衰老过程中胶原纤维的沉积速度减慢。     

人松果体结缔组织纤维的构筑——消蚀法扫描电镜观察

为证明人松果体结缔组织纤维的排列，用消蚀扫描电镜法对该器官做了观察。松果体囊由胶原纤维束构成，囊表而可观察到大量由胶原纤维编织成的孔隙。起自囊的胶原纤维构成小叶间隔，分隔松果体实质为直径２００－４００μｍｊ的小叶。囊和隔由疏松排列的胶原细纤维构成。     

人窦房结和房室结微血管的扫描电镜观察

本文用4例新鲜婴儿尸体,采用血管铸型扫描电镜法,观察人窦房结、房室结微血管的立体构筑。结果表明,窦房结的血管床是由微血管网构筑成一椭圆形网状结构,中央动脉贯穿于结的长轴,由此动脉向周围发出分支,逐级分为许多微动脉和毛细血管前微动脉,最后在结的浅部分成毛细血管网。毛细血管后微静脉的收集范围,则显示出按区收集的特点。而房室结微血管构型是一扁圆形的微血管网,结的浅部为一薄层比较细密的毛细血管网。透过网眼,可见有粗大的、彼此吻合的窦状静脉丛。房室结动脉由结一侧进入结内,向周围逐级分支,形成毛细血管前微动脉,穿行于静脉丛之间,在结的浅部连于毛细血管网。毛细血管后微静脉的始端有环形缩窄,为平滑肌压痕。     

受压状态下关节软骨胶原纤维结构的电镜观察

目的：观察关节软骨在受压后其胶原纤维结构的形态学变化，方法：对12件人股骨头软骨标本进行分组加载，扫描电镜观察胶原纤维结构，结果：受压后，胶原纤维弯曲，随压力增大而加重，甚至断裂，结论：异常高应力负荷可使关节软骨胶原纤维损伤甚至断裂。     

豚鼠窦房结的组织学构筑

目的 :探讨豚鼠窦房结的形态学特征。方法 :常规石蜡切片 ,HE、Masson和VanGieson染色 ,光镜观察和测量豚鼠窦房结的组织结构 ;HPIAS 1 0 0 0图像分析仪定量测量结细胞 ;电镜观察窦房结的亚微结构。结果 :豚鼠窦房结位于右心耳和上腔静脉根部交界处的静脉外侧壁内 ,呈蹄铁样 ,分为头、干两部分。大小约为 :0 .1 8mm× 0 .3 2mm× 3 .63mm。主要由P和T细胞构成。P细胞横径约为 7.73 μm ,面积为 2 3 4.2 1 μm2 ,T细胞横径约为 1 3 .1 5μm ,面积约为 490 .3 5 μm3。窦房结动脉大多位于结的边缘 ,结内胶原纤维丰富。结论 :豚鼠窦房结有明显的物种差异 ,但细胞成分与其它动物相似。     

骺板牵拉延长术后胶原纤维的扫描电镜观察

目的：探讨骺板胶原纤维受到牵拉后其胶原纤维超微构筑的变化。方法：将经外固定器牵拉分离后儿童胫骨远端及近端骺板制成标本进行扫描电镜观察。结果：骺板经牵拉后其胶原纤维超微构筑发生了改变，胶原纤维趋向于力的纵轴方向排列。结论：经牵拉后，骺板胶原纤维超微构筑发生了改变，排列具有定向性。     

人窦房结的神经发育

本文用14例不同发育阶段的胚胎,以及新生儿与成人各2例的窦房结,以Faworsky法银染,光镜观察。8周胚在腔房交界处的前内侧,出现局限性增厚,该区致密,细胞较小,尚未包绕窦房结动脉;至12周时,该区称为窦房结,已见少量纤细的神经纤维。16～22周胚胎的窦房结切面呈椭圆形,窦房结动脉位于中央,已能分出三个区。中央网状区内,神经节与神经纤维丰富,心外膜下神经节较少。神经细胞为多极神经元,胞体大小不一,核质比例为幼稚形细胞状态。24～32周的胚胎心外膜下神经节数量逐渐增多,可以分出深、浅两组;结内神经节则逐渐减少。此阶段结外节已多于结内节。38周胚胎与新生儿的窦房结神经配布,与24～32周胚胎阶段相似,只是更趋于成熟,接近成年人窦房结的神经分布特点。     

实验性肝纤维化大鼠胶原网络构筑的扫描电镜观察

目的 探讨肝纤维化大鼠胶原网络的三维形态构筑的变化。方法 采用健康雄性Wislar大鼠,随机分为对照组和肝纤维化组,后者采用60％的四氯化碳植物油皮下注射,造成肝纤维化大鼠模型,分别于实验的第10周和12周末取材,作为10周和12周肝纤维化组,行天狼猩红显色,光镜下观察和氢氧化钠浸渍,扫描电镜下观察胶原网络的构筑。结果 扫描电镜下,随着肝纤维化程度的加重,增生的胶原纤维交织成网,分隔包裹正常肝组织,形成大小不等圆形或椭圆型肝组织团块,近似于“蜂窝状”囊性的假小叶结构;相邻假小叶之间的胶原纤维沉积明显,并与包裹门管区和血管的纤维鞘相延续为间隔。与对照组相比,10周肝纤维化组形成了尚不完整的假小叶囊,12周组的小叶囊致密完整。结论 肝纤维化时胶原纤维超微构筑发生了改变,增生的胶原网络主要由粗、细纤维构成。     

家兔窦房结的形态学研究

目的 :了解窦房结的形态结构。方法 :取 1 0例家兔心脏 ,常规石蜡包埋整心连续切片 ,HE染色、Masson三色染色和磷钨酸苏木素染色后 ,在光镜下观察。在光镜观察的基础上 ,另取 2例家兔窦房结对其特化的P细胞和T细胞进行透射电镜观察。结果 :家兔窦房结位于界沟上部 ,约 1 / 3跨越腔耳角 ,形态大小变化较大 ,内部有丰富的小血管分布 ,附近有一较大动脉和神经分布 ,未见分层分部现象。P细胞内可见线粒体、电子致密颗粒和高尔基氏器 ,细胞核大而圆可见核仁。T细胞介于P细胞与普通心肌细胞之间。结论 :家兔窦房结的位置较高 ,其细胞发育较为成熟 ,个体差异较大     

Alteration of cartilage surface collagen fibers differs locally after immobilization of knee joints in rats

The purpose of this study was to examine the ultrastructural changes of surface cartilage collagen fibers, which differ by region and the length of the experimental period in an immobilization model of rat. Male Wistar rats were randomly divided into histological or macroscopic and ultrastructural assessment groups. The left knees of all the animals were surgically immobilized by external fixation for 1, 2, 4, 8 or 16 weeks (n = 5/time point). Sagittal histological sections of the medial mid-condylar region of the knee were obtained and assessed in four specific regions (contact and peripheral regions of the femur and tibia) and two zones (superficial and deep). To semi-quantify the staining intensity of the collagen fibers in the cartilage, picrosirius red staining was used. The cartilage surface changes of all the assessed regions were investigated by scanning electron microscopy (SEM). From histological and SEM observations, the fibrillation and irregular changes of the cartilage surface were more severe in the peripheral region than in the contact region. Interestingly, at 16 weeks post-immobilization, we observed non-fibrous structures at both the contact and peripheral regions. The collagen fiber staining intensity decreased in the contact region compared with the peripheral region. In conclusion, the alteration of surface collagen fiber ultrastructure and collagen staining intensity differed by the specific cartilage regions after immobilization. These results demonstrate that the progressive degeneration of cartilage is region specific, and depends on the length of the immobilization period.     

窦房结的外科解剖

在95例成人与30例儿童心脏上,用解剖显微镜观察、解剖和测量了窦房结。在成人,此结多数可以用色苍白,质地硬.有动脉穿入等特点,在界沟上部予以确认,儿童则不易辨识。描述了右心耳嵴顶端的变异和界沟上部的切迹,并提出了窦房结三角以确认此结。对结的外表标志及其肌肉连系结合外科和功能进行了讨论。     

反复力竭运动大鼠心脏窦房结细胞T-型钙离子通道的变化

背景：目前,运动医学领域关于运动对窦房结细胞T-型钙离子通道(T-Ca²⁺通道)的影响鲜见报道。 目的：分析2周力竭跑台运动对大鼠心脏窦房结T-Ca²⁺通道亚基Cav3.1 mRNA表达及通道电流密度的影响。 方法：健康雄性SD大鼠50只共分5组。对照组10只大鼠不进行任何运动训练,一次力竭组20只大鼠在正常饲养2周后,进行一次速度25 m/min,坡度为0°跑台训练至力竭;反复力竭组20只大鼠运动方式及强度同一次力竭组,跑台训练1次/d,每周运动6 d,休息1 d,共训练2周。运动组大鼠分别于运动后0 h及 24 h (各10只)取材,应用实时荧光定量PCR技术测定T-Ca²⁺通道亚基Cav3.1 mRNA表达变化,应用细胞急性分离及全细胞膜片钳技术测定通道电流密度变化,以观察跑台训练运动对大鼠心脏窦房结细胞膜上T-Ca²⁺通道的影响。 结果与结论：与对照组相比,反复力竭运动0 h和反复力竭运动24 h组Cav3.1 mRNA表达明显下降(P < 0.01)。反复力竭运动0 h和反复力竭运动24 h组T-Ca²⁺通道ICa,T电流密度明显低于对照组及一次力竭组(P < 0.01)。结果表明,2周反复力竭跑台训练可引起窦房结细胞膜T-Ca²⁺通道亚基Cav3.1 mRNA表达及ICa,T电流密度减少,这可能引起窦房结细胞舒张期自动除极及自律活动减慢,提示反复力竭运动对于T-Ca²⁺通道的影响可能成为运动引发窦房结功能障碍及运动性心律失常的离子通道机制之一。 中国组织工程研究杂志出版内容重点：组织构建;骨细胞;软骨细胞;细胞培养;成纤维细胞;血管内皮细胞;骨质疏松;组织工程全文链接：     

The role of the calcium and the voltage clocks in sinoatrial node dysfunction

Recent evidence indicates that the voltage clock (cyclic activation and deactivation of membrane ion channels) and Ca(2+) clocks (rhythmic spontaneous sarcoplasmic reticulum Ca(2+) release) jointly regulate sinoatrial node (SAN) automaticity. However, the relative importance of the voltage clock and Ca(2+) clock for pacemaking was not revealed in sick sinus syndrome. Previously, we mapped the intracellular calcium (Ca(i)) and membrane potentials of the normal intact SAN simultaneously using optical mapping in Langendorff-perfused canine right atrium. We demonstrated that the sinus rate increased and the leading pacemaker shifted to the superior SAN with robust late diastolic Ca(i) elevation (LDCAE) during β-adrenergic stimulation. We also showed that the LDCAE was caused by spontaneous diastolic sarcoplasmic reticulum (SR) Ca(2+) release and was closely related to heart rate changes. In contrast, in pacing induced canine atrial fibrillation and SAN dysfunction models, Ca(2+) clock of SAN was unresponsiveness to β-adrenergic stimulation and caffeine. Ryanodine receptor 2 (RyR2) in SAN was down-regulated. Using the prolonged low dose isoproterenol together with funny current block, we produced a tachybradycardia model. In this model, chronically elevated sympathetic tone results in abnormal pacemaking hierarchy in the right atrium, including suppression of the superior SAN and enhanced pacemaking from ectopic sites. Finally, if the LDCAE was too small to trigger an action potential, then it induced only delayed afterdepolarization (DAD)-like diastolic depolarization (DD). The failure of DAD-like DD to consistently trigger a sinus beat is a novel mechanism of atrial arrhythmogenesis. We conclude that dysfunction of both the Ca(2+) clock and the voltage clock are important in sick sinus syndrome.     

Comparative iTRAQ analysis of protein abundance in the human sinoatrial node and working cardiomyocytes

Our objective was to assess the changes in protein abundance in the human sinoatrial node (SAN) compared with working cardiomyocytes to identify SAN‐specific protein signatures. Four pairs of samples (the SAN and working cardiomyocytes) were obtained postmortem from four human donors with no evidence of cardiovascular disease. We performed protein identification and quantitation using two‐dimensional chromatography‐tandem mass spectrometry with isobaric peptide labeling (iTRAQ). We identified 451 different proteins expressed in both the SAN and working cardiomyocytes, 166 of which were differentially regulated (110 were upregulated in the SAN and 56 in the working cardiomyocytes). We identified sarcomere structural proteins in both tissues, although they were differently distributed among the tested samples. For example, myosin light chain 4, myosin regulatory light chain 2‐atrial isoform, and tropomyosin alpha‐3 chain levels were twofold higher in the SAN than in working cardiomyocytes, and myosin light chain 3 and myosin regulatory light chain 2‐ventricular/cardiac muscle isoform levels were twofold higher in the ventricle tissue than in SAN. We identified many mitochondrial oxidative phosphorylation, β‐oxidation, and tricarboxylic acid cycle proteins that were predominantly associated with working cardiomyocytes tissue. We detected upregulation of the fatty acid omega activation pathway proteins in the SAN samples. Some proteins specific for smooth muscle tissue were highly upregulated in the SAN (e.g. transgelin), which indicates that the SAN tissue might act as the bridge between the working myocardium and the smooth muscle. Our results show possible implementation of proteomic strategies to identify in‐depth functional differences between various heart sub‐structures.     

跑台训练对大鼠心脏窦房结快激活IKr通道的影响

目的 探讨大鼠两周力竭跑台训练对心脏窦房结快激活延迟整流钾离子(Ikr)通道的影响.方法 SD大鼠分为对照组(C组)、一次力竭组(O组)、两周反复力竭组(R组),每组10只.C组大鼠不进行任何运动训练,O组大鼠在正常饲养两周后,进行1次跑台训练至力竭,R组每天进行1次跑台训练,训练时长为2周.训练组大鼠分别于运动后0及24h取材,O组以O-0 h和O-24 h命名,R组以R-0 h和R-24 h命名.用实时荧光定量PCR和Western blot技术测定Ikr通道亚基ERG1b mRNA及蛋白质表达,用全细胞膜片钳技术测定通道电流密度.结果 1)R-0 h及R-24 h组ERG1b mRNA及蛋白质表达明显低于C组及O-0 h组(P＜0.01).2)R-0 h及R-24 h组Ikr通道电流密度分别为(0.89±0.03) pA/pF和(1.02 ±0.07) pA/pF,明显低于C组及O-0 h组的(1.81 ±0.12) pA/pF和(1.69±0.08) pA/pF (P ＜0.01).结论 反复力竭运动可引起大鼠心脏窦房结细胞膜IKr通道亚基ERG1b基因表达及电流密度减少,这可能成为运动引发窦房结功能障碍的离子通道机制之一.     

Modulation of rabbit sinoatrial node activation sequence by acetylcholine and isoproterenol investigated with optical mapping technique

Aims: Changes in the rabbit sinoatrial node (SAN) activation sequence with the cholinergic and adrenergic factors were studied. The correlation between the sinus rhythm rate and the leading pacemaker site shift was determined. The hypothesis concerning the cholinergic suppression of nodal cell excitability as one of the mechanisms associated with pacemaker shift was tested. Methods: A high‐resolution optical mapping technique was used to register beat‐to‐beat changes in the SAN activation pattern under the influence of the cholinergic and adrenergic factors. Results: Acetylcholine (10 μm ) and strong intramural parasympathetic nerve stimulation caused a pacemaker shift as well as rhythmic slowing and the formation of an inexcitable region in the central part of SAN. In this region the generation of action potentials was suppressed. The slowing of the sinus rhythm (which exceeded 12.8 ± 3.1% of the rhythm control rate) always accompanied the pacemaker shift. Isoproterenol (10, 100 nm , 1 μm ) and sympathetic postganglionic nerve stimulation also evoked a pacemaker shift but without formation of an inexcitable zone. The acceleration of the sinus rhythm, which exceeded 10.5 ± 1.3% of the control rate of the rhythm, always accompanied the shift. Conclusions: Both cholinergic and adrenergic factors cause pacemaker shifts in the rabbit SAN. While modest changes in the sinus rhythm do not coincide with the pacemaker shift, greater changes always accompany the shift and may be caused by it, according to one hypothesis. The formation of an inexcitable zone at the place where the leading pacemaker is situated is one of the mechanisms associated with pacemaker shift.