心钠素对内皮素促大鼠心肌细胞增殖的影响

内皮素(endothelin,ET)是新近发现的血管活性多肽,具有强大的缩血管作用。近年来的大量研究表明,ET还有强效的促进血管平滑肌细胞(VSMC)增殖的作用,在高血压、动脉粥样硬化发病过程中有重要意义。心钠素(atrial natriuretic peptide,ANP)亦是近年发现的血管活性多肽,有明显的利钠、利尿     

γ—干扰素对内皮素促平滑肌细胞增殖效应的影响

血管内皮细胞分泌的内皮素(ET)不仅是强烈的血管收缩剂,而且具有强烈的促血管平滑肌细胞(VSMC)增殖的效应。近年来发现许多细胞因子除参与免疫调节外,还参与心血管功能的调节。γ-干扰素(IFN-γ)具有抑制VSMC增殖,调节细胞分化、增生的作用。本工作在培养的自发性高血庄大鼠(SHR)和对照WKY大鼠的VSMC上,观察了IFN-γ和ET对VSMC增殖和钙含量的影响,以探讨IFN-γ和ET对VSMC增殖的相互调控关系。     

内皮素对清醒家兔具有致热原作用

内皮素(endothelin,ET)是最强的收缩血管和促血管平滑肌细胞增殖的心血管活性多肽,在原发性高血压、急性心肌梗塞等心血管疾病中有重要的发病学意义;但其在体内的生理和病理生理作用尚未完全阐明。最近Tomoyuski等首次发现内皮素在体内具有致热原作用。     

低切应力作用下体外培养动脉内皮细胞内皮素的表达

研究了切应力对完整血管的生物学作用以及应力引起血管重建过程中内皮素(ET)的变化．采用血管体外应力培养系统,将一段完整的猪颈总动脉在体外进行培养,设切应力分别为2Pa(％组)和0．5Pa(S5组),设置2、4、6．8．10．12、14．16和18h共9个时相观察点,非平衡法放射免疫检测灌流液中的ET含量．通过Logistic曲线方程拟合,分析切应力作用下完整动脉ET表达变化规律。结果显示：S20组ET总体变化不明显;S5组分泌速率在前12．37h内明显上升,而后又逐渐下降趋于稳定,且始终高于S20组。说明低切应力作用下ET的表达及分泌增高．结果提示,在低切应力引起的血管重建中,ET可能起着重要作用。     

内皮素研究的进展（综述）

血管的舒缩足受神经、体液因素和血管壁内部的局部调节机制共同作用而实现的。从Furchgott等1980年发现内皮细胞源性舒张因子以来,人们开始把很大注意力放在内皮细胞在心血管系统功能活动中的作用的研究上。最近,研究人员从血管内皮细胞培养基上清液中提取到一种强烈缩血管肽,命名为内皮素(ET)。试验发现它具有强烈的缩血管作用。     

内皮素促进下丘脑—垂体—卵巢激素的释放

最近发现,内皮素(endothelin,ET)不仅具有强烈的血管活性作用,还可能作为激素调节肽参与性激素的调节。在下丘脑-垂体-卵巢轴的器官和胎盘都有丰富的ETmRNA和ET受体存在。Kanyicska等在培养的雌性大鼠垂体前叶细胞,应用ET-3(10~(-14)～10~(-6)mol/L)明显抑制垂体前叶细胞分泌催乳素(PRL),增加促黄体生成素(LH)、促卵泡素(FSH)和促甲状腺素(TSH)的释放。ET的刺激效     

发现内皮素A型受体拮抗剂

万有制药中央研究所与探索研究所共同从微生物中筛选出与血管内皮细胞产生的血管收缩肽、内皮素(ET)的A型受体(ET_A受体)特异结合、没有生理作用的物质(拮抗剂),并确定了其构造。这一成果为世界首创。通过分子设计开发使受体的亲和性提高140倍的物质,继体外实验之后,小鼠体内试验发现了ET受体拮抗剂的作用。ET受体拮抗剂将来有可能成为与ET有关的高血压和气喘病的治疗药。也可有助于阐明ET和疾患的关系。这项成果已在东京召开的第46届日本生物化学大会上发表。该小组使用大量表达ET_A受体的猪大动脉平滑肌培养细胞,从爱知县土壤中采收的微生物产物中找出     

内皮素和内皮素受体研究的某些进展

内皮素(endothelin,ET)是从血管内皮细胞中提取纯化的含21个氨基酸残端的多肽,有强烈收缩血管作用,对神经、内分泌、心脏、肾脏、胃肠道、呼吸道和细胞分裂等都有广泛影响。在一定条件下,血管内皮能分泌内皮素。血管平滑肌上有特异的内皮素受体。内皮素可直接作用于相应的受体或经其它途径使平滑肌收缩而发挥其作用。     

怀菊花总黄酮对自发性高血压大鼠的降压作用及机制研究

研究怀菊花总黄酮对自发性高血压大鼠(SHR)的降压作用及其机制。将SHR随机分为模型组、怀菊花总黄酮高、中、低剂量组和依那普利阳性对照组。采用无创血压计测定血压及心率,采用放射免疫法测定血浆内皮素(ET)、血管紧张素Ⅱ(AngⅡ)、醛固酮(ALD)、肾素活性(PRA)含量。结果表明怀菊花总黄酮能够降低SHR的血压(P0.01)、心率(P0.05)、血浆ET(P0.05)、AngⅡ(P0.01)、ALD(P0.01)、PRA(P0.01),其降压机制可能与改善内皮功能和抑制肾素-血管紧张素-醛固酮系统(RAAS)活性有关。     

17β—雌二醇下调血管平滑肌内皮素A型受体的表达

为进一步探讨雌激素对心血管的保护作用,实验在双侧卵巢去势大鼠模型和培养的血管平滑肌细胞（VSMCs)上,观察17β－雌二醇（E2）对血管反应性及VSMCs增殖的影响,以RT－PCR和Western blot检测内皮素受体（ETAR）的表达,结果显示：去势雌性大鼠血管对内皮素（ET－1）的反应性明显增高,ETAR特异性受体阻断剂BQ123能完全阻断ET－1对VSMCs增殖的影响,E2能明显抑制ET－1对VSMCs增殖的作用,RT－PCR结果显示E2能抑制ETAR mRNA的表达,Western blot进一步证实E2能抑制ETAR蛋白表达,E2受体阻断剂Tamoxifen能部分抑制ET－1对VSMCs的增殖及ETAR的mRNA和蛋白 的表达。以上结果提示;ET－1促VSMCs增殖的效应主要是由ETAR介导的,雌激素能通过下调ETAR来抑制ET－1对VSMCs 促增殖的作用和血管对ET－1的反应,且此作用与雌激素受体有关。     

植物吸收利用有机氮营养研究进展

植物矿质营养学问世以后,人们一直认为无机氮是植物吸收氮素的主要形态.随着研究手段的改进和研究内容的不断深入,现已证实许多没有菌根的维管植物都可以直接吸收可溶性有机氮,特别是小分子的氨基酸.由此引起了人们对植物有机营养、植物营养方式多样化问题的重视.研究表明：氨基酸可以通过多种方式释放到土壤溶液中,土壤中的氨基酸主要来源于微生物、动植物及其代谢产物等.土壤氨基酸含量受土壤温湿度、所施的有机肥料、生长的植物种类及其生长发育时期的影响.植物对氨基酸的吸收是一个主动吸收过程,受载体调节,并与能量状况有关,同时受介质中pH和温度的影响.但是有关植物吸收氨基酸的机理及其生态过程还需进行深入的研究.     

Establishment of vascular endothelial cell lines in a serum-free culture and the discovery of endothelin and a Vasoactive Intestinal Contractor (VIC)

Immortal vascular endothelial cell lines were established and utilized for the production of an endothelium-derived contraction factor (EDCF) in a serum-free medium. After the discovery of Endothelin (21 amino acid peptide, ET) as an EDCF, a prepro ET cDNA isolated from human tissue was used to examine the expression of ET and its regulation in human endothelial cells. A gene family of ET was shown in mouse by using prepro ET cDNA as a probe. Thus, a novel peptide, Vasoactive Intestinal Contractor (VIC) homologous to ET was deduced from the sequence of one of these genes. VIC was confirmed to induce vasocontraction as well as intestinal contraction. Northern blot analysis indicated that this gene was expressed in the intestine but not in endothelial cells. A cloning and sequencing of prepro VIC cDNA from mouse intestine suggest that a VIC-like peptide, as well as VIC, are co-synthesized by cleavage from prepro VIC with 160 amino acids.     

Establishment of vascular endothelial cell lines in a serum-free culture and the discovery of endothelin and a Vasoactive Intestinal Contractor (VIC)

Immortal vascular endothelial cell lines were established and utilized for the production of an endothelium-derived contraction factor (EDCF) in a serum-free medium. After the discovery of Endothelin (21 amino acid peptide, ET) as an EDCF, a prepro ET cDNA isolated from human tissue was used to examine the expression of ET and its regulation in human endothelial cells. A gene family of ET was shown in mouse by using prepro ET cDNA as a probe. Thus, a novel peptide, Vasoactive Intestinal Contractor (VIC) homologous to ET was deduced from the sequence of one of these genes. VIC was confirmed to induce vasocontraction as well as intestinal contraction. Northern blot analysis indicated that this gene was expressed in the intestine but not in endothelial cells. A cloning and sequencing of prepro VIC cDNA from mouse intestine suggest that a VIC-like peptide, as well as VIC, are co-synthesized by cleavage from prepro VIC with 160 amino acids.     

植物对氨基酸的吸收及其生理效应

<正> 在古代的农业系统中,所用的肥料都是有机肥,人们并不知道植物依赖于何种物质得以生长繁衍。自1840年,德国化学家李比希(J.U.Liebig)发表了《化学在农业和植物生理学上应用》一书后,人们对植物的营养有了新的认识,认识到矿物质对植物的重要性。李比希在书中指出:“土壤中矿物质是一切绿色植物唯一的养料。植物可以完全依赖于无机物质而生长发育。这一观点即为“植物的矿质营养学说”。该学说后来为生产实践所充分证明,并成为农业化学     

Vegetation cover regulates the quantity,quality and temporal dynamics of dissolved organic carbon and nitrogen in Antarctic soils

Populations of the two native Antarctic vascular plant species (Deschampsia antarctica and Colobanthus quitensis) have expanded rapidly in recent decades, yet little is known about the effects of these expansions on soil nutrient cycling. We measured the concentrations of dissolved organic carbon (DOC) and nitrogen (DON), amino acids and inorganic N in soils under these two vascular plant species, and under mosses and lichens, over a growing season at Signy Island in the maritime Antarctic. We recorded higher concentrations of nitrate, total dissolved nitrogen, DOC, DON and free amino acids in soil under D. antarctica and C. quitensis than in lichen or moss dominated soils. Each vegetation cover gave a unique profile of individual free amino acids in soil solution. Significant interactions between soil type and time were found for free amino acid concentrations and C/N ratios, indicating that vascular plants significantly change the temporal dynamics of N mineralization and immobilization. We conclude that D. antarctica and C. quitensis exert a significant influence over C and N cycling in the maritime Antarctic, and that their recent population expansion will have led to significant changes in the amount, type and rate of organic C and N cycling in soil.     

Eyeing endothelins: A cellular perspective

Endothelin is an endogenous vasoactive peptide that is considered among the most potent vasoconstrictor substances known. In addition to its vascular effects, endothelins and their receptors have been shown to be present in the eye and to have a number of ocular actions that may be important for ocular homeostasis, but, in excess can be a potential contributor to ocular neuropathy in glaucoma. The current review focuses on the cellular and molecular aspects of endothelins and its receptors in the eye with an emphasis on its relationship to ocular function and its potential role in the etiology of glaucoma pathophysiology.     

内皮素A型受体胞内区cDNA的克隆及序列分析

为研究内皮素受体在细胞内的信号传导途径,通过聚合酶链反应(PCR)的方法获得了480bp的内皮素A型受体胞内区cDNA片段,将其克隆进载体pUC19进行核苷酸序列分析,结果表明克隆的cDNA片段与报道的内皮素A型受体cDNA序列只有一个碱基的不同且为同义突变。最后,将克隆的cDNA片段定向克隆进酵母双杂交系统中的引诱蛋白表达载体pGBT9,为探寻与内皮素A型受体相互作用的蛋白质打下了基础。     

Primary structure of bovine endothelin ETB receptor and identification of signal peptidase and metal proteinase cleavage sites.

A cDNA clone corresponding to the entire coding region of the bovine ETB endothelin receptor mRNA was isolated from a lung cDNA library and sequenced. The cDNA encodes 441 amino acids: 26 constituting an NH2-terminal signal peptide and 415 constituting the mature receptor. The signal peptidase cleavage site was determined by direct amino acid sequencing of purified receptor. A comparison of the predicted amino acid sequence with the available bovine ETA and rat ETB endothelin receptor sequences revealed 63 and 85% homology, respectively. Endothelin receptors of various species are known to be very sensitive to a certain metal proteinase(s) and have been shown to be converted to a lower Mr form in the absence of EDTA. The metal proteinase cleavage site was also determined by direct protein sequencing of the proteolysis product. The amino acid sequence (Ala-Gly-X-Pro-Pro-Arg) surrounding the cleavage site (between Ala-79 and Gly-80) is conserved among the ETB endothelin receptors, explaining the above mentioned proteolytic conversion from the higher to lower Mr forms observed in various species.     

Endothelin--a new family of endothelium-derived peptides with widespread biological properties

Endothelin (ET) is a novel family of three isopeptides (ET-1, ET-2, ET-3) each containing twenty-one amino acids and two disulfide bonds. Initially isolated from the supernatant of cultured porcine aortic endothelial cells, ET is stored as a preproform and released through an unusual proteolytic cleavage. In general, ET-1, ET-2, ET-3 differ quantitatively but not qualitatively in their biologic activity. ET have potent contractile activity in a variety of isolated tissues including arteries veins, trachea, duodenum urinary bladder and uterus. In vivo, ET possesses potent vasodilator and vasoconstrictor properties. Although the mechanisms mediating the hemodynamic effects of ET are not entirely clarified, recent evidence indicates a role for endothelium-derived relaxant factor (EDRF), protein kinase C and extracellular calcium. Moreover, ET appears to produce inflammation and bronchoconstriction through the formation of arachidonic acid metabolites via the cyclooxygenase pathway. The presence of ET binding sites in blood vessels and in several organ systems suggests ET may have important regulatory functions, which remain to be determined.