高糖对培养大鼠心肌细胞牛磺酸转运的影响及其可能机制

目的：观察不同浓度葡萄糖对细胞牛磺酸(taurine)转运功能的影响。方法：在培养的大鼠心肌细胞上,用^3H标记的牛磺酸测定细胞牛磺酸转运和竞争性定量RTPCR测定细胞牛磺酸转运体(TAUT)mRNA含量。结果：不同浓度葡萄糖(10～30mmol/L)孵育,抑制细胞^3H-牛磺酸转运,呈时间依赖性。与对照组比较,高糖(20mmol／L和30mmol／L)使心肌细胞牛磺酸摄入量显著减少,其^3H-牛磺酸转运的最大速率(Vmax)减少,心肌细胞TAUTmRNA含量较对照组减少。结论：高糖抑制心肌细胞牛磺酸转运,这与TAUT的牛磺酸结合位点减少和TAUT基因转录水平下调有关。     

牛磺酸对高糖培养下视网膜Mü ller细胞GFAP和TAUT表达的影响

目的:通过检测高糖培养条件下视网膜Müller细胞神经纤维酸性蛋白(glial fibrillary acid protein,GFAP)和牛磺酸转运蛋白(taurine transporter,TAUT)的表达变化,观察葡萄糖对Müller细胞牛磺酸(taurine)转运功能的影响,探讨牛磺酸对早期糖尿病视网膜病(DR)可能的保护作用。方法:高糖培养大鼠视网膜Mǜller细胞,用免疫细胞荧光化学双染色、Western blotting技术检测不同浓度牛磺酸干预下Müller细胞GFAP及TAUT的蛋白表达。结果:高糖可引起Müller细胞GFAP表达增强,TAUT表达减弱;牛磺酸可减弱高糖引起的Müller细胞GFAP表达增强,TAUT在0．1mmol/L～10mmol/L的牛磺酸干预后表达增强。结论:牛磺酸可以抑制高糖导致的Müller细胞功能改变。     

牛磺酸对高糖培养下视网膜Mü ller细胞GFAP和TAUT表达的影响

目的：通过检测高糖培养条件下视网膜Mü ller细胞神经纤维酸性蛋白（glial fibrillary acid protein,GFAP）和牛磺酸转运蛋白（taurine transporter,TAUT）的表达变化,观察葡萄糖对Mü ller细胞牛磺酸（taurine）转运功能的影响,探讨牛磺酸对早期糖尿病视网膜病（DR）可能的保护作用.方法：高糖培养大鼠视网膜Mü ller细胞,用免疫细胞荧光化学双染色、Western blotting技术检测不同浓度牛磺酸干预下Mü ller细胞GFAP及TAUT的蛋白表达.结果：高糖可引起Mü ller细胞GFAP表达增强,TAUT表达减弱;牛磺酸可减弱高糖引起的Mü ller细胞GFAP表达增强,TAUT在0.1mmol/L～10 mmo1/L的牛磺酸干预后表达增强.结论：牛磺酸可以抑制高糖导致的Müller细胞功能改变.     

缺血／再灌注损伤对心肌细胞核膜NTPase活性和mRNA出核转运的影响

目的：观察家兔心肌缺血／再灌注（I／R）损伤对心肌细胞核膜核苷三磷酸酶（NTPase）动力学及mRNA出核转运的变化。方法：制备家兔离体心脏I／R模型,密度梯度离心法制备心肌细胞核膜,按Tiffany等的方法测定NTPase活性及mRNA的转运率。结果：心肌细胞核膜NTPase在以ATP或GTP为底物时,与对照组比较,I／R组最大反应速率（Vmax)分别降低26％及22％（P＜0．01）。Km值分别升高54％及72％（P＜0．01）;而缺血组Vmax及Km值较对照组无明显差异。以ATP或GTP启动反应时I／R组10min内心肌细胞核mRNA转出率分别较对照组降低27％及32％（P＜0．01）;而缺血组与对照组相比并无显著性差异（P＞0．05）。结论：心肌缺血／再灌注损伤时,心肌细胞核膜受损,核膜上NTPase活性降低,导致细胞核膜mRNA出核受阻,从而可能影响蛋白质的合成表达。     

高血压大鼠心脏和血管MAPK磷酸酶-1表达的改变及对平滑肌细胞增殖的影响

目的和方法：比较自发性高血压大鼠（SHR）和对照（WKY）大鼠心脏和主动脉丝裂素活化蛋白激酶磷酸酶－1（MKP－1）及细胞外信号调节激酶（ERK－1）的表达,并观察用磷酸钙共沉淀方法转染MKP－1基因对血管紧张素Ⅱ（Ang Ⅱ）刺激平滑肌细胞（VSMC）^3H－胸腺叫啶（^3H-TdR)掺入的影响,以探讨MKP－1在细胞增殖中的调节作用。结果：①与WKY大鼠相比,SHR心脏和主动脉MKP－1呈低表达,分别降低53％和45％（P均＜0．01）;而SHR心脏和主动脉ERK－1呈明显高表达（P均＜0．01）,SHR心脏和主动脉ERK－1与MKP－1蛋白比值明显高于WKY。②AngⅡ 10^-7mol/L刺激VSMC增殖较对照组增加257％（P＜0．01）,转染野生型MKP－1基因细胞可使AngⅡ刺激的^3H-TdR掺入较未转染的细胞降低63％（P＜0．05）,转染突变型MKP－1基因和转染空载体的VSMC对AngⅡ的刺激与单纯AngⅡ组相比无明显抑制作用（P＞0．05）。结论：SHR心血管组织中促增殖肥大的ERK－1表达较其失活的MKP－1占优势,并且MKP－1可显著抑制AngⅡ的VSMC增殖。     

内源性CO在缺氧性肺动脉高压大鼠肺血重构中的作用

目的和方法：应用逆转录聚合酶链式反应（RT－PCR）、双波长分光光度法,右心导管及维多利亚蓝染色方法,动态观察慢性缺氧不同时间点大鼠肺吕诱导型血红素氧合酶（HO－1）基因表达,内源性CO生成,肺动脉压力及构型的变化,探讨内源性CO大鼠缺氧性肺动脉高压肺血管重构中的作用。结果：（1）正常大鼠肺组织可表达少量HO－1mRNA,缺氧5、10、15d大鼠肺组织HO－1mRNA含量分别增加2．3、3．6、4．0倍（P＜0．01）,动脉血中COHb分别较正常大鼠增加1．2、2．6和2．9倍（P＜0．1或P＜0．05）。同时RVSP升高。光镜下可见IAPA血管壁增厚,管腔变窄。（2）Hemin可使缺氧大鼠肺组织HO－1mRNA和动脉血中COHb保持在高水平（分别高达正常对照组的5．2和3．7倍,P＜0．01或P＜0．05）,能部分地抑制缺氧时大鼠RVSP的升高,减轻IAPA的病理改变。结论：在慢性缺氧性肺动脉高压大鼠肺组织中HO－1基因的表达增加,内源性CO生成增多。Hemin促进HO－1基因表达和内源性CO手成,可抑制肺动脉压升高,阻抑制血管重构,对缺陷氧性肺动脉高压的形成有一定的防治作用。     

卡托普利对实验性2型糖尿病心肌病大鼠模型心脏保护作用

目的研究卡托普利对实验性2型糖尿病心肌病（T2DC）模型动物心脏保护作用和可能机制。方法以高糖脂饲料负荷30mg／kg剂量链脲佐菌素一次性腹腔注射建立T2DC大鼠模型,观察卡托普利45mg／kg灌胃给药6周对模型动物血糖和血脂水平,心脏功能和结构变化,心肌脂肪酸含量以及心肌组织过氧化物增殖体激活受体α（PPAR）和葡萄糖转运体4（GLUT4）基因表达等指标的影响。结果与T2DC大鼠模型比较,卡托普利给药后,左心室收缩压、左心室最大收缩速率、左心室最大舒张速率的绝对值和心输出量分别显著增加15％、77％、52％和54％（P〈0．05或P〈0．01）;室间隔厚度降低40％（P〈0．001）;血浆糖化血红蛋白和心肌组织游离脂肪酸含量分别降低31％和24％（P〈0．01,P〈0．05）;心肌组织PPARα基因表达显著降低（P〈0．05）,GLUT4基因表达显著增加（P〈0．05）。结论卡托普利可以显著改善T2DC模型动物心脏功能、抑制心室重构,其作用机制可能同调节与能量代谢相关基因表达、减轻心脏内脂肪积聚有关。     

自发性高血压大鼠心脏中ACE,AT1R,ACE2和MasR表达变化的研究

目的：通过观察血管紧张素转化酶（ACE）和血管紧张素转化酶2（ACE2）在Wistar-京都种大鼠（WKY）和自发性高血压（SHR）大鼠心脏组织中表达的差异,探讨ACE与ACE2在自发性高血压大鼠高血压形成中的作用。方法：自由饲喂14周龄WKY和SHR雄性大鼠一周后,用BSN-II多通道无创测压系统测定大鼠收缩压（SBP）、舒张压（DBP）、心率（HR）并称重;放免法测定血浆中血管血管紧张素Ⅱ（AngII）含量;Real-time PCR测定心脏组织中ACE,ATI受体（ATIR）,ACE2和Mas受体（MasR）mRNA的表达水平;Western blot法检测心脏组织中ACE2的蛋白表达。结果：SHR大鼠SBP和DBP均显著高于WKY大鼠（P〈0.01）;两组大鼠心率和体重无显著差异（P〉0.05）;SHR大鼠血浆中AngII含量显著升高（P〈0.05）;与WKY大鼠相比,SHR大鼠心脏中ACE mRNA表达均显著升高（P〈0.05）,ACE2的mRNA和蛋白表达水平均显著下降（P〈0.05）;心脏组织中AT1R和MasR的mRNA表达没有显著性变化（P〉0.05）。结论：ACE与ACE2表达失调是SHR大鼠高血压形成的主要原因之一,其机理可能与局部组织RAS系统ACE-AngII-AT1R通路过度活跃,ACE2-Ang（1-7）-MasR通路相对不足有关。     

高血压对大鼠心肌PPAR-γ表达水平的影响及其意义

以自发性高血压大鼠（SHR）为模型,Wistar-Kyoto大鼠（WKY）为正常对照,探讨过氧化物酶体增殖物激活受体γ（PPAR-γ）表达水平,在高血压肥厚心肌中的变化及其意义.4周龄(4w)、16周龄(16w) SHR及WKY称量体重（BM）后取心脏,分别测量左心室（LV）、室间隔（IS）、右心室（RV）湿重（WM）,并应用免疫组织化学技术,检测大鼠心肌细胞PPAR-γ表达;应用蛋白质印迹和RT-PCR技术,检测 4w、16w SHR LV、IS、RV PPAR-γ蛋白质和mRNA水平.发现4w SHR LVWM/BM、ISWM/BM、RVWM/BM与同龄WKY相比无显著性差异（P＞0.05）,PPAR-γ的蛋白质和mRNA表达水平亦相似（P＞0.05）;16w SHR LVWM/BM和ISWM/BM较同龄WKY明显增高（P＜0.01）,而PPAR-γ的蛋白质和mRNA水平显著降低（P＜0.01）,16w SHR RVWM/BM与16wWKY相比差异无显著性（P＞0.05）,PPAR-γ的蛋白质表达水平亦无显著性差异（P＞0.05）,mRNA水平较WKY略减弱（P＜0.05）.实验结果提示,长期压力负荷过重导致SHR LV和IS心肌代偿性肥厚,肥厚心肌中PPAR-γ蛋白质和mRNA表达水平显著降低,推测心肌细胞PPAR-γ表达受抑制,可能参与了高血压心室重塑的发生机制.     

自发性高血压大鼠心脏与红细胞L-Arg转运的改变

研究自发性高血压大鼠 (spontaneouslyhypertensiverats ,SHR)心脏L 精氨酸 /一氧化氮 (L Arg/NO)系统的改变及其与红细胞L Arg转运的关系。检测 12周龄 (W)、16W、captopril治疗 4周后的 16WSHR (SHR C)及同龄Wistar Kyoto (WKY)大鼠心脏的L Arg转运、tNOS活性、NO 2 NO 3 和cGMP含量以及红细胞L Arg转运的改变。结果显示 ,SHR心室肌组织L Arg高亲和转运成分的最大转运速率 (Vmax)及低亲和转运成分的米氏常数 (Km)均明显低于WKY大鼠 ;但高亲和转运成分的Km 值和低亲和转运成分的Vmax则无明显改变 ;SHR C组的改变基本同 12W组。心肌组织tNOS活性的变化无统计学意义。NO 2 NO 3 及cGMP含量则分别较WKY组降低 2 4 6 %、19 8% (P >0 0 5 ,P <0 0 5 ,12W组 ) ,5 2 5 %、6 0 4% (P <0 0 1,P <0 0 1,16W组 )和 14 8%、2 3 % (P >0 0 5 ,P <0 0 5 ,SHR C组 )。tNOS活性、cGMP含量与LVW/BW呈负相关 ,r=0 45 0 7,P =0 0 5 (NOS) ,r=0 6 898,P <0 0 1(cGMP)。红细胞L Arg转运的改变与心脏一致 ,且其Vmax与心肌组织高亲和转运成分的Vmax呈正相关 ,r=0 5 6 0 6 ,P =0 0 1;与LVW /BW呈负相关 ,r=- 0 6 2 31,P <0 0 1。以上结果表明 ,SHR心室肌组织L Arg/NO系统活动被抑制 ,其抑制程度与心肌肥厚     

碱性成纤维细胞生长因子增加大鼠血管一氧化氮及内皮素的生成

研究碱性成纤维细胞生长因子（ｂａｓｉｃ ｆｉｂｒｏｂｌａｓｔ ｇｒｏｗｔｈ ｆａｃｔｏｒ,ｂＦＧＦ）对自发性高血压大鼠（ＳＨＲ）和ＷＫＹ大鼠血管一氧化氮（ＮＯ）及内皮素生成的影响。取ＳＨＲ和ＷＫＹ大鼠主动脉制成血管薄片,以１０、１００ｎｇ／ｍｌ ｂＦＧＦ（终浓度）分别孵育６ｈ,测定血管组织中一氧化氮合酶（ＮＯＳ）活性及孵育液中亚哨酸盐（ＮＯ２）和内皮素含量。结果显示：ＳＨＲ主动脉组织ＮＯＳ活性较Ｗ     

Unique endothelin receptor binding in kidneys of ETB receptor deficient rats

The study investigated whether the amelioration of endothelial dysfunction by candesartan (2 mg.kg-1.day-1; 10 wk) in spontaneously hypertensive rats (SHR) was associated with modification of hepatic redox system. Systolic arterial pressure (SAP) was higher (P < 0.05) in SHR than in Wistar-Kyoto rats (WKY) and was reduced (P < 0.05) by candesartan in both strains. Acetylcholine (ACh) relaxations were smaller (P < 0.05) and contractions induced by ACh + NG-nitro-l-arginine methyl ester (l-NAME) were greater (P < 0.05) in SHR than in WKY. Treatment with candesartan enhanced (P < 0.05) ACh relaxations in SHR and reduced (P < 0.05) ACh + l-NAME contractions in both strains. Expression of aortic endothelial nitric oxide synthase (eNOS) mRNA was similar in WKY and SHR, and candesartan increased (P < 0.05) it in both strains. Aortic mRNA expression of the subunit p22phox of NAD(P)H oxidase was higher (P < 0.05) in SHR than in WKY. Treatment with candesartan reduced (P < 0.05) p22phox expression only in SHR. Malonyl dialdehyde (MDA) levels were higher (P < 0.05), and the ratio reduced/oxidized glutathione (GSH/GSSG) as well as glutathione peroxidase activity (GPx) were lower (P < 0.05) in liver homogenates from SHR than from WKY. Candesartan reduced (P < 0.05) MDA and increased (P < 0.05) GSH/GSSG ratio without affecting GPx. Vessel, lumen, and media areas were bigger (P < 0.05) in SHR than in WKY. Candesartan treatment reduced (P < 0.05) media area in SHR without affecting vessel or lumen area. The results suggest that hypertension is not only associated with elevation of vascular superoxide anions but with alterations of the hepatic redox system, where ANG II is clearly involved. The results further support the key role of ANG II via AT1 receptors for the functional and structural vascular alterations produced by hypertension.     

剪切应力下内皮细胞内皮素及其mRNA的表达

应用Ｎｏｒｔｈｅｒｎ印迹方法研究高血压（ＳＨＲ）和正常（ＷＫＹ）大鼠脑微血管培养内皮细胞,在剪切应力０、０．５、１、２Ｐａ作用下２４ｈ后检测内皮素及其基因ｍＲＮＡ表达上的区别。结果表明,在剪切应力０、０．５、１Ｐａ下,ＷＫＹ大鼠的内皮细胞随着剪切应力加大,其内皮素水平及其基因的ｍＲＮＡ的表达均比ＷＫＹ相应组的为高。在剪切应力２Ｐａ时,ＷＫＹ和ＳＨＲ大鼠的内皮细胞内皮素及其基因的ｍＲＮＡ表达水平不同     

大鼠运动性肥大心脏心肌血管内皮生长因子及其基因表达的研究

目的和方法：血管内皮生长因子（ｖａｓｃｕｌａｒｅｎｄｏｔｈｅｌｉａｌｇｒｏｗｔｈｆａｃｔｏｒ,ＶＥＧＦ）是新近确定的一种特异作用于血管内皮细胞的活性肽。最近发现正常心肌细胞可表达ＶＥＧＦ,高血压肥大心脏心肌ＶＥＧＦ及基因表达增强,但对运动性心肌肥大时的变化尚不清楚。本实验采用免疫组化和分子杂交方法,对游泳运动１０周大鼠稳定期肥大心脏心肌ＶＥＧＦ及其基因表达进行研究。结果：ＷｉｓｔａｒＫｙｏｔｏ（ＷＫＹ）大鼠、自发性高血压大鼠（ｓｐｏｎｔａｎｅｏｕｓｌｙｈｙｐｅｒｔｅｎｓｉｖｅｒａｔｓ,ＳＨＲ）和运动大鼠心肌细胞浆内均有特异性ＶＥＧＦ染色颗粒,但运动大鼠心肌细胞胞浆内染色颗粒增加最明显。Ｎｏｒｔｈｅｒｎ分子杂交结果表明三组大鼠心肌均有ＶＥＧＦｍＲＮＡ表达,其中ＳＨＲ表达最强,运动大鼠比ＷＫＹ大鼠增强,但低于ＳＨＲ。结论：目前对这一结果的生理意义还不清楚,推测可能与心肌肥大时细胞间质血管增生有关。     

Physiological significance of taurine and the taurine transporter in intestinal epithelial cells

Summary. Taurine transport in human intestinal epithelial Caco-2 cells was down-regulated by culturing the cells in taurine-containing media and was up-regulated in a taurine-free medium. This adaptive regulation was associated with changes in both the Vmax and Km values of taurine transport. A change in the mRNA level of the taurine transporter (TAUT) in this regulation was also observed. The presence of such a regulatory mechanism for maintaining the intracellular taurine content at a certain level suggests that taurine plays an important role in the intestinal cell functions. The intracellular taurine content was increased when Caco-2 cells were exposed to a hypertonic stress. TAUT was up-regulated via the increased expression of TAUT mRNA in the hypertonic cells, suggesting that taurine serves as an osmolyte and protects the cells from osmotic stress. Similar up-regulation of TAUT was observed in the small intestine of water-deprived rats. Received January 25, 2000/Accepted January 31, 2000     

Effects of oxidative stress on the expression of antioxidative defense enzymes in spontaneously hypertensive rat hearts

Little is known concerning the effect of oxidative stress on the expression of antioxidative enzymes in the decompensated cardiac hypertrophy of spontaneously hypertensive rats (SHR), considered as a model of dilative cardiomyopathy in man. Superoxide dismutase (SOD), catalase, and glutathione peroxidase (GPx) were characterized in isolated perfused hearts of 18 month old SHR and the age-matched normotensive control Wistar-Kyoto (WKY) rats, before and after 30 min infusion of 25 microM H(2)O(2). After infusion of H(2)O(2), aortic flow decreased in WKY from 26.2 +/- 2.2 to 16.0 +/- 0.8 ml/min (p <.05) but not in SHR (18.2 +/- 1.9 vs. 20.7 +/- 2.2 ml/min). This protection was related to the higher myocardial activities of GPx, MnSOD and CuZnSOD in SHR, compared with those of the WKY group. Although total SOD activity in the SHR fell after H(2)O(2) exposure (to 1.81 +/- 0.13 from 3.56 +/- 0.49 U/mg of protein), catalase activity increased (to 2.46 +/- 0.34 from 1.56 +/- 0.29 k min(-1)mg(-1)protein), compared with the pre-infusion period (p <.05 in each case). In additional studies, hearts were subjected to 30 min of global ischemia followed by 30 min of reperfusion. The results obtained in ischemic/reperfused hearts show the same changes in enzyme activities measured as it was observed in H(2)O(2) perfused hearts, indicating that oxidative stress is independent of the way it was induced. The higher catalase activity derived from elevated mRNA synthesis. The antioxidative system in dilative cardiomyopathic hearts of SHR is induced, probably due to episodes of oxidative stress, during the process of decompensation. This conditioning of the antioxidative potential may help overcome acute stress situations caused by reactive oxygen species in the failing myocardium.     

Taurine transporter in fetal T lymphocytes and platelets: differential expression and functional activity

Transplacental transfer of taurine, a -amino acid essential for fetal and neonatal development, constitutes the primary source of taurine for the fetus. Placental transport of taurine is compromised in pregnancies complicated by intrauterine growth restriction, resulting in a reduced concentration of taurine in cord plasma. This could impact on fetal cellular metabolism as taurine represents the most abundant intracellular amino acid in many fetal cell types. In the present study, we have used pure isolates of fetal platelets and T lymphocytes from cord blood of placentas, from normal, term pregnancies, as fetal cell types to examine the cellular uptake mechanisms for taurine by the system transporter and have compared gene and protein expression for the taurine transporter protein (TAUT) in these two cell types. System activity in fetal platelets was 15-fold higher compared with fetal T lymphocytes (P < 0.005), mirroring greater TAUT mRNA expression in platelets than T lymphocytes (P < 0.005). Cell-specific differences in TAUT protein moieties were detected with a doublet of 75 and 80 kDa in fetal platelets compared with 114 and 120 kDa in fetal T lymphocytes, with relatively higher expression in platelets. We conclude that greater system activity in fetal platelets compared with T lymphocytes is the result of relatively greater TAUT mRNA and protein expression. This study represents the first characterization of amino acid transporters in fetal T lymphocytes. cord blood cells; amino acid; taurine transporter protein; system