雌激素对氧化型低密度脂蛋白诱导的血管内皮细胞凋亡的影响

目的：观察雌激素（１７β－雌二醇）对氧化型低密度脂蛋白（ｏｘＬＤＬ）诱导人脐静脉内皮细胞（ＨＵＶＥＣ）凋亡的影响。方法 以ＨＵＶＥＣ为对象,观察不同浓度的１７β－雌二醇（１,１０和１００μｍｏｌ／Ｌ）对ｏｘＬＤＬ（４μｇ／Ｌ）诱导的凋亡的影响。结果 不同剂量的１７β－雌二醇对使用ｏｘＬＤＬ诱导的ＨＵＶＥＣ凋亡减少７０％￣９３％,其抑制呈明显的正向量效应关系,１７β－雌二醇１μｍｏｌ／Ｌ组细胞凋亡占     

Endotheliopathy of liver sinusoidal endothelial cells in liver disease

Liver is the largest solid organ in the abdominal cavity, with sinusoid occupying about half of its volume. Under liver disease, hemodynamics in the liver tissue dynamically change, resulting in injury to liver sinusoidal endothelial cells (LSECs). We discuss the injury of LSECs in liver diseases in this article. Generally, in noninflamed tissues, vascular endothelial cells maintain quiescence of circulating leukocytes, and unnecessary blood clotting is inhibited by multiple antithrombotic factors produced by the endothelial cells. In the setting of inflammation, injured endothelial cells lose these functions, defined as inflammatory endotheliopathy. In chronic hepatitis C, inflammatory endotheliopathy in LSECs contributes to platelet accumulation in the liver tissue, and the improvement of thrombocytopenia by splenectomy is attenuated in cases with severe hepatic inflammation. In COVID-19, LSEC endotheliopathy induced by interleukin (IL)-6 trans-signaling promotes neutrophil accumulation and platelet microthrombosis in the liver sinusoids, resulting in liver injury. IL-6 trans-signaling promotes the expression of intercellular adhesion molecule-1, chemokine (C-X-C motif) ligand (CXCL1), and CXCL2, which are the neutrophil chemotactic mediators, and P-selectin, E-selectin, and von Willebrand factor, which are involved in platelet adhesion to endothelial cells, in LSECs. Restoring LSECs function is important for ameliorating liver injury. Prevention of endotheliopathy is a potential therapeutic strategy in liver disease.     

Actions of 4-chloro-3-ethyl phenol on internal Ca2+ stores in vascular smooth muscle and endothelial cells

1. Recently, 4-chloro-3-ethyl phenol (CEP) has been shown to cause the release of internally stored Ca²⁺, apparently through ryanodine-sensitive Ca²⁺ channels, in fractionated skeletal muscle terminal cisternae and in a variety of non-excitable cell types. Its action on smooth muscle is unknown. In this study, we characterized the actions of CEP on vascular contraction in endothelium-denuded dog mesenteric artery. We also determined its ability to release Ca²⁺, by use of Ca²⁺ imaging techniques, on dog isolated mesenteric artery smooth muscle cells and on bovine cultured pulmonary artery endothelial cells.
2. After phenylephrine-(PE, 10 μM) sensitive Ca²⁺ stores were depleted by maximal PE stimulation in Ca²⁺-free medium, the action of CEP on refilling of the emptied PE stores was tested, by first pre-incubating the endothelium-denuded artery in CEP for 15 min before Ca²⁺ was restored for a 30 min refilling period. At the end of this period, Ca²⁺ and CEP were removed, and the arterial ring was tested again with PE to assess the degree of refilling of the internal Ca²⁺ store.
3. In a concentration-dependent manner (30, 100 and 300 μM), CEP significantly reduced the size of the post-refilling PE contraction (49.4, 28.9 and 5.7% of control, respectively) in Ca²⁺-free media. This suggests that Ca²⁺ levels are reduced in the internal stores by CEP treatment. CEP alone did not cause any contraction either in Ca²⁺-containing or Ca²⁺-free Krebs solution.
4. Restoring Ca²⁺ in the presence of PE caused a large contraction, which reflects PE-induced influx of extracellular Ca²⁺. The contraction of tissues pretreated with 300 μM CEP was significantly less compared with controls. However, tissues pretreated with 30 and 100 μM CEP were unaffected. Washout of CEP over 30 min produced complete recovery of responses to PE in Ca²⁺-free and Ca²⁺-containing medium suggesting a rapid reversal of CEP effects.
5. Concentration-response curves were constructed for PE, 5-hydroxytryptamine (5-HT) and K⁺ in the absence of and after 30 min pre-incubation with 30, 100 and 300 μM CEP. In all cases, CEP caused a concentration-dependent depression of the maximum response to PE (84.8, 43.4 and 11.6% of control), 5-HT (65.4, 25.7 and 6.9% of control) and K⁺ (77.6, 41.1 and 10.8% of control).
6. Some arterial rings were pre-incubated with ryanodine (30 μM) for 30 min before the construction of PE concentration-response curves. In Ca²⁺-free Krebs solution, ryanodine alone did not cause any contraction. However, 58% (11 out of 19) of the tissues tested with ryanodine developed contraction (6.9±1.2% of 100 mM K⁺ contraction, n=11) in the presence of external Ca²⁺. EC₅₀ values for PE in ryanodine-treated tissues (1.7±0.25 μM, n=16) were not significantly different from controls (2.5±0.41 μM, n=22). Maximum contractions to PE (118.5±4.4% of 100 mM K⁺ contraction, n=16) were also unaffected by ryanodine when compared to controls (129±4.2%, n=23).
7. When fura-2 loaded smooth muscle cells (n=13) and endothelial cells (n=27) were imaged for Ca²⁺ distribution, it was observed that 100 and 300 μM CEP in Ca²⁺-free medium caused Ca²⁺ release in both cell types. Smooth muscle cells showed a small decrease in cell length. Addition of EGTA (5 mM) reversed the effect of CEP on intracellular Ca²⁺ to control values.
8. These data show, for the first time in vascular smooth muscle and endothelial cells, that CEP releases Ca²⁺ more rapidly than ryanodine. Unlike ryanodine, CEP caused no basal contraction but depressed contractions to PE, 5-HT and K⁺. The lack of basal contraction may result from altered responsiveness of the contractile system to intracellular Ca²⁺ elevation.

     

Coronary microcirculation: autoregulation and metabolic control

The majority of studies axamining the regulation of coronary blood flow and vascular resistance have considered the coronary circulation as being composed of large conduit vessels and resistance vessels. Recently, it has become apparent that regulation of coronary microvascular resistance is not distributed uniformly, but varies across different segments or microdomains of the vasculature. Generally, small arterioles, those less than 100 m in diameter, respond differently than larger arterioles and small arteries. There are major differences in the level of autoregulatory control, myogenic control, endothelial modulation and control by metabolic factors across these various microvascular domains. There are also transmural variations which may account for some of the differences in coronary blood observed between epicardial and endocardial regions. In addition, interactions between these various regulatory mechanisms further complicate the understanding of coronary microvascular regulation. Importantly however, it may be these complex interactions and heterogeneous regulatory mechanisms which allow for adequate perfusion of the myocardium under an extreme range of metabolic conditions. This segmental distribution of regulation suggests an integrative hypothesis of regulation whereby a variety of mechanisms play a role in the overall response.Invited Contributions to the Symposium Regulation of coronary blood flow, held at the XV. World Congress of the International Society for Heart Research in Prague 1995     

Endothelial lipopigment as an indicator of α-tocopherol deficiency in two equine neurodegenerative diseases

Two spontaneous neurodegenerative diseases of the horse, equine motor neuron disease (EMND) and equine degenerative myeloencephalopathy (EDM), have been associated with -tocopherol deficiency, and both were characterized by prominent accumulations of endothelial lipopigment in the small vessels of the spinal cord. These endothelial pigment deposits appear to be reversible. In EMND horses pasture-supplemented for 9 months or more after the progression of weakness and wasting had arrested, there was very little endothelial lipopigment. The origin and the potential effects of these endothelial lipopigment accumulations are discussed.     

糖尿病大鼠血管内皮损伤的实验研究

内皮损伤研究方兴未艾。为了探讨血管损伤与早发性糖尿病大血管病变之关系,分别随机抽取３０只成年健康雌性Ｗｉｓｔａｒ大鼠和四氧嘧啶诱导的糖尿病大鼠,测定其循环内皮细胞计数（ＣＥＣ）和血管紧张素转化酶（ＡＣＥ）血清活力。结果显示：糖尿现鼠ＡＣＥ高于对照ＡＣＥ（９８０．０２±１３２．１８ｕ／５６０．０７±１５０．０３ｕ）,糖尿病鼠ＣＥＣ（２．５２±０．６７个／０．９ｕｌ）高于健康鼠ＣＥＣ（０．７２±０．２     

血小板源性生长因子对于培养内皮细胞血管内皮细胞生长因子水平的影响

通过免疫组织化学的方法,观察血小板源性生长因子（PDGF）对于培养脐静脉内皮细胞血管内皮细胞生长因子（VEGF）水平的影响,揭示PDGF促进新生血管形成的机制。实验结果：缺氧培养时内皮细胞胞浆VEGF水平上升;不同剂量的PDGF在常规或缺氧培养条件下均能增加内皮细胞VEGF水平,且呈剂量依赖性,提示PDGF可能通过直接促血管形成生长因子的介导作用间接促进新生血管的形成。     

不同底物对HUVEC在血管内支架上粘附生长的影响

目的研究不同底物对人脐静脉内皮细胞（ＨＵＶＥＣ）在支架上粘附及生长的影响。方法：分别用Ｆｉｂｒｉｎｅｃｔｉｎ、ｐｏｌｙＬｌｙｓｉｎｅ处理血管内支架后将其置入ＨＵＶＥＣ悬液,定时旋转血管内支架,使内皮细胞在支架上充分粘附。比较ＨＵＶＥＣ在底物处理的支架与裸支架上粘附率及生长状况的差异。结果：ＨＵＶＥＣ在裸支架、ｐｏｌｙＬｌｙｓｉｎｅ及Ｆｉｂｒｉｎｅｃｔｉｎ处理血管内支架上的粘附率分别为１９．９２％、３９．８２％、６４．９％,３者比较有统计学上的差异;ＨＵＶＥＣ在Ｆｉｂｒｉｎｅｃｔｉｎ处理的支架上的生长状况也优于其它两种情况。结论：底物Ｆｉｂｒｉｎｅｃｔｉｎ和ｐｏｌｙＬｌｙｓｉｎｅ处理能提高内皮细胞在支架上的粘附率。     

抗氧化维生素对内皮细胞增殖及凋亡的影响

目的：　观察氧化低密度脂蛋白（ｏｘＬＤＬ）对内皮细胞增殖与凋亡的影响以及抗氧化维生素（维生素Ｅ、维生素Ｃ及β－胡萝卜素）对内皮细胞的防治效应。方法：　在体外培养的小牛主动脉内皮细胞中分别加入不同浓度的抗氧化维生素,作用１２ｈ 后,再与终浓度为０．１ｇ Ｐｒ／Ｌ的ｏｘＬＤＬ共同培养２４ｈ,采用噻唑蓝比色分析法和流式细胞仪分析法对贴壁内皮细胞进行检测,分别观察抗氧化维生素对经ｏｘＬＤＬ作用的内皮细胞的形态、生长增殖、细胞周期及凋亡的影响。结果：　（１）维生素Ｅ和维生素Ｃ能显著减轻ｏｘＬＤＬ对内皮细胞形态的损伤作用;β－胡萝卜素作用稍弱。（２）三种抗氧化维生素均可降低ｏｘＬＤＬ对内皮细胞生长增殖的抑制作用,使其抑制率降低。（３）三种抗氧化维生素均可促进内皮细胞由Ｇ１ 期进入ＤＮＡ合成的Ｓ期,促进内皮细胞的增殖并阻止内皮细胞凋亡的发生。结论：　维生素Ｅ、维生素Ｃ及β－胡萝卜素均可减轻ｏｘＬＤＬ在形态、增殖及凋亡等方面对内皮细胞的损伤作用,这可能是抗氧化维生素加速内皮细胞损伤后修复、促进内皮细胞增殖,从而发挥其抗动脉粥样硬化形成的部分机制。