荧光探针法测定家兔肾脏内髓集合管细胞单层Cl-/HCO3-交换

用BCECF/AM荧光探针法,测定不同浓度CO2培养的IMCD细胞Cl-/HCO3-交换.结果显示高CO2组的碱负荷后pHi恢复率为0.132±0.015pHi/min,明显高于对照组(0.117±0.016 pHi/ min,P＜0.05).低CO2组为0.111±0.015pHi/min,与对照组相比无显著差别.可见荧光探针法测定原代培养家兔肾脏IMCD细胞Cl-/HCO3-交换,具有操作简便、稳定可靠、经济安全等优点.     

大鼠糖尿病早期肾脏皮质Na+,K+-ATP酶α1-亚单位的表达

目的：探讨大鼠糖尿病早期肾脏肥大和肾脏皮质Na^ ，K^ -ATP酶α1-亚单位mRNA表达的变化。方法：采用单剂量腹腔注射链脲佐菌素(streptozocozin,STZ)诱发大鼠糖尿病，分别在糖尿病第1、3、7天测定肾脏肥大指数，并以RT-PCR技术检测肾脏皮质Na^ ，K^ -ATP酶α1-亚单位mRNA的表达。结果：大鼠糖尿病早期血糖显著升高，肾脏肥大，肾脏皮质Na^ ，K^ -ATP酶α1-亚单位mRNA的表达明显降低。结论：肾脏皮质Na^ ，K^ -ATP酶α1-亚单位mRNA表达的改变可能是糖尿病早期肾脏肥大的一个因素。     

MDCK细胞Kca鉴定及粉防己碱（Tet）对MDCK细胞Kca的影响

目的：MDCK细胞KCA鉴定及探讨Tet对该通道的影响。方法：①利用膜片钳单通道记录技术，在inside-out膜片上，利用更换浴液中[K^ ]和[Ca^2 ]的方法对通道进行鉴定；②Inside-out膜片上，记录不同浓度的Tet和顺铂(DDP)对MDCK细胞KCa的Am(Current Amplitude，)、Po(Probability of Open,)、     

加味玉屏风散对创伤应激小鼠CD4+CD25+调节性T细胞影响的实验研究

目的观察创伤应激状态下及口服加味玉屏风散(玉屏风散加党参)后对小鼠CD4+CD25+Tr细胞影响.方法采用小鼠截肢应激模型,将50只BALB/c小鼠随机分为5组正常对照组(A)、应激对照组(B)、应激+加味玉屏风散高(C)、中(D)、低(E)剂量组.采用流式细胞仪检测小鼠外周血和脾细胞悬液中CD4+CD25-T、CD4-CD25+T、CD4+CD25+Tr的细胞数.结果创伤后72h小鼠外周血及脾细胞悬液中CD4+CD25+Tr细胞比例明显升高(P<0.01),CD4+CD25-T细胞、CD4-CD25+T细胞比例明显降低(P<0.01);给予加味玉屏风散后各组小鼠外周血及脾细胞悬液中CD4+CD25+Tr细胞比例明显降低(P<0.01),CD4+CD25-T细胞、CD4-CD25+T细胞比例明显升高(P<0.01);其中C组与A组比较差异无统计学意义(P>0.05).结论创伤后小鼠CD4+CD25+Tr表达增强,加味玉屏风散可有效抑制其表达.     

托伐普坦对小鼠内髓集合管细胞系水通道蛋白及肾小管功能的影响

目的探讨托伐普坦对小鼠内髓集合管细胞系水通道蛋白2、细胞凋亡以及肾小管功能的影响。方法用不同浓度的托伐普坦刺激小鼠内髓集合管细胞后,Western blot检测水通道蛋白2的蛋白表达,caspase3活性检测试剂盒检测caspase3活性,MTS法及流式细胞计量术检测细胞凋亡;用不同浓度的托伐普坦治疗心肌梗死模型小鼠后,ELISA检测β_2-微球蛋白(β_2-MG)与N-乙酰-β-D-葡萄糖苷酶(NAG)含量。结果托伐普坦呈剂量依赖性,显著降低水通道蛋白2的蛋白表达(P0.05),但是不影响caspase 3的活性及细胞凋亡,托伐普坦不影响小鼠尿中β_2-MG与NAG的含量。结论托伐普坦显著降低内髓集合管细胞水通道蛋白2的蛋白表达,不影响其细胞凋亡及小鼠肾小管功能。     

不同保护剂对大鼠肾脏冻融法脱细胞的影响

目的:利用不同保护剂对大鼠肾脏进行预处理,辅助冻融法脱细胞获得脱细胞支架,优化冻融脱细胞工艺。方法:采用不同保护剂预处理大鼠肾脏,放入-20℃环境下进行冷冻,12 h后进行37℃水浴复温,然后利用Triton X-100灌注24 h、PBS灌注2 h。最后通过CT三维重构、染色切片、蛋白质定量以及力学性能分析等手段评估所得脱细胞支架。结果:未添加保护剂组血管网络损伤较大,洗脱效果一般。添加不同保护剂组的血管网络也均存在一定的损伤,但其中10%DMSO和5%海藻糖组血管网络保留得较为完整。但10%DMSO组DNA等物质残留过多,5%海藻糖组洗脱细胞效果良好。结论:加载保护剂能够对冻融法脱细胞起到一定的促进作用,且能保护大鼠肾脏内部血管网络等结构,但不同保护剂对冻融法脱细胞的作用效果不同。     

CD86对CD8+T细胞分化的影响

目的：探讨CD86(B7-2)对CD8^ T细胞分化的影响。方法：用限制性内切酶Xho Ⅰ酶切质粒pCDM8得到CD86基因，并将其插入pCDNA3，用BamH Ⅰ酶切鉴定。用脂质体法介导pCDNA3-CD86真核表达载体转染人肝癌细胞株HMCT／21，600μg/ml G418筛选，稳定且高表达CD86的抗性克隆用流式细胞仪进行鉴定。从健康志愿者血中分离外周血单个核细胞(PB-MC)，使PBMC与靶细胞之比为20：1，共同培养48h后，用流式细胞仪检测CD3^ T细胞内IL-4和IFN-γ的表达率。结果：成功构建pCDNA3-CD86真核表达载体；CD86在HMC7721-CD86细胞中的表达率为30．8％，而在HMC7721细胞中的表达率为0．98％；健康志愿者CD3^ T细胞内IL-4和IFN-γ的表达率分别为1．92％和24．4％；PBMC与靶细胞共同培养48h后，无论是否用IFN-α刺激，IL-4，IFN-γ的阳性比值在HMC7721-CD86转染组均大于1，而在HMC7721未转染组均小于1。结论：在细胞培养中，CD86可诱导CD8^ T细胞活化，并向Tc2表型转化。     

p16蛋白过表达对哺乳动物细胞带3蛋白阴离子交换功能的影响

目的: 研究p16过表达对HeLa细胞带3蛋白(band 3)阴离子交换功能的影响。方法:细胞免疫组织化学法检测HeLa细胞中p16和带3蛋白的表达。采用PCR方法将p16 cDNA亚克隆到pEGFP-C1上,经双酶切和DNA测序鉴定后将其转染HeLa细胞,在荧光显微镜下观察细胞转染效率。应用6甲基-3-磺丙基-1-喹啉-水化合物(SPQ)荧光探针检测带3蛋白的阴离子交换功能。结果:在HeLa细胞中p16和带3蛋白表达均为阳性。双酶切和DNA测序结果证明所扩增的p16 cDNA序列与报道序列相同。细胞转染后在荧光显微镜下可观察到60%以上的细胞发出荧光。转染pEGFP-C1-p16后细胞的阴离子交换功能增强。结论:p16对HeLa细胞带3蛋白的阴离子交换功能有促进作用。     

常压氧对缺血再灌注大鼠大脑皮层1型Na~+/H~+交换蛋白的影响

目的:研究常压氧(NBO)对缺血再灌注大鼠脑组织1型Na+/H+交换蛋白(NHE1)水平的影响。方法:采用线栓法构建大脑中动脉缺血(MCAO)大鼠模型,术后2 h进行神经功能评分。MCAO模型构建成功者进行再灌注,随机分为MCAO组和NBO组,NBO组于再灌注后给予常压氧治疗。各组大鼠分别在NBO治疗后0、2、4、6、12、24 h处死,取脑皮层组织进行HE染色后观察脑组织形态结构的改变,并采用免疫荧光法及Western Blot法检测脑组织NHE1蛋白和缺氧诱导因子-1α(HIF-1α)的蛋白表达水平。结果:与假手术组相比,模型组神经功能评分显著增高(P 0. 05); HE染色结果显示MCAO组和NBO组大鼠缺血2 h时大脑皮层组织均无明显病理结构改变,随着再灌注时间的延长,MCAO组大鼠大脑皮层组织病理改变逐渐增加,NBO组大鼠的脑组织病理改变明显减轻;免疫荧光检查和Western Blot检测结果显示MCAO组和NBO组在起始2 h内,大脑皮层组织NHE1和HIF-1α蛋白表达水平没有明显变化,随着再灌注时间的延长,MCAO组NHE1蛋白和HIF-1α蛋白表达水平逐渐增加,NBO组NHE1蛋白和HIF-1α蛋白表达水平稍有增加,但是其表达水平明显低于MCAO组(P 0. 05)。结论:常压氧疗法可以下调缺血再灌注后大脑皮层组织NHE1蛋白和HIF-1α蛋白的表达,减轻大鼠脑缺血再灌注损伤,促进大鼠神经功能恢复,具有脑损伤保护作用。     

K562细胞转染HLA-B分子对NK细胞杀伤功能的影响

为了研究不同HLA B分子对NK细胞杀伤活性的影响 ,我们分别构建pcDNA3 HLA B 390 5 2、B 2 70 4、B 5 1 0 2 2基因真核表达载体 ;借助脂质体将各质粒转染入K5 6 2细胞 ,经G4 1 8筛选 ,分别获得阳性表达细胞株 ;并应用LDH法检测转染细胞对不同个体外周血NK细胞杀伤活性的抑制效应。结果显示 :与转染了空质粒的对照组相比 ,外周血NK细胞对K5 6 2 B39的杀伤率无明显影响 ,而对K5 6 2 B2 7,K5 6 2 B5 1的杀伤率降低。当使用针对NK细胞受体KIR3DL1的单抗DX9封闭NK细胞后 ,此抑制效应大部分消失。提示靶细胞表达HLA Bw4分子可明显抑制NK细胞的杀伤效应 ,而表达HLA Bw6分子对NK细胞杀伤功能无明显影响     

离体灌流大鼠心脏Na^＋／H^＋交换的意义

离体大鼠等容收缩心脏预灌流30min,再换用含20mmol/L NH_4Cl的K-H液灌流10min后,随机分为两组:(1)对照组(n=5): 恢复常规K-H液冲洗15min;(2)给药组(n=5):在常规K-H液冲洗时,加入0.5mmol/L amiloride以抑制Na~+/H~+交换。结果如下:预灌及NH_4Cl负荷阶段,两组血液动力学指标无明显差别;在冲洗时,对照组血液动力学指标逐渐恢复,而给药组心肌一直处于挛缩状态。对照组心肌组织Na~+、Ca~(2+)、K~+含量高于给药组;而心肌组织MDA及冠脉流出液中LDH活性则低于给药组。因此,酸负荷状态下,Na~+/H~+交换是pHi及生理活动恢复的重要调节机制,抑制这—过程,将加重心肌组织的损伤,以至于死亡。     

Role of Na+/Ca2+ exchange in transcellular Ca2+ transport across primary cultures of rabbit kidney collecting system

Cells from connecting tubule and cortical collecting duct of rabbit kidney were isolated by immunodissection with mAb R2G9 and cultured on permeable filters. Confluent monolayers developed an amiloride-sensitive transepithelial potential difference of –50±1 mV (lumen negative) and a transepithelial resistance of 507±18 cm². Transepithelial Ca²⁺ transport increased dose-dependently with apical [Ca²⁺] and, in solutions containing 1 mM Ca²⁺, the active transcellular Ca²⁺ transport rate was 92±2 nmol h^–1 cm^–2. Transcellular Ca²⁺ transport was dependent on basolateral Na⁺ (Na _b ⁺ ). Isoosmotic substitution of Na _b ⁺ for N-methylglucamine resulted in a concentration-dependent decrease in Ca²⁺ absorption, with maximal inhibition of 67±5%. A Hill plot of the Na⁺-dependence yielded a coefficient of 1.9±0.4, indicating more than one Na⁺ site on a Na⁺-dependent Ca²⁺ transport system. In addition, the absence of Ca _b ²⁺ resulted in a significant increase in Ca²⁺ transport both in the presence and absence of Na _b ⁺ . Added basolaterally, ouabain (0.1 mM) inhibited Ca²⁺ transport to the same extent as did Na⁺-free solutions, while bepridil (0.1 mM), an inhibitor of Na⁺/Ca²⁺ exchange, reduced Ca²⁺ transport by 32±6%. Methoxyverapamil, felodipine, flunarizine and diltiazem (10 M) were without effect. Depolarisation of the basolateral membrane, by raising [K⁺]_b to 60 mM, significantly decreased transcellular Ca²⁺ transport, which is indicative of electrogenic Na⁺/Ca²⁺ exchange. In conclusion, active Ca²⁺ transport in the collecting system of rabbit kidney is largely driven by basolateral Na⁺/Ca²⁺ exchange. However, a residual Ca²⁺ absorption of about 30% was always observed, suggesting that other Ca²⁺ transport mechanisms, presumably a Ca²⁺-ATPase, participate as well.     

Selective inhibition of the Na+/H+ exchanger type 3 activates CO2/H+-sensitive medullary neurones

Hypercapnia as well as lowered intracellular pH (pH_i) increase the bioelectric activity of CO₂/H⁺-sensitive neurones (VLNcs) of the ventrolateral medulla oblongata. Here we describe that immunoreactive Na⁺/H⁺ exchanger (NHE3) is present in ventrolateral neurones from medullary organotypic cultures (obex level). To test whether VLNcs can be acidified and thereby activated by inhibition of NHE3, we used the novel high-affinity NHE3-inhibitors S1611 and S3226. Both drugs raised the firing rates of VLNcs to at least 150% of the control values, and depolarized membrane potential by up to 15 mV at concentrations (0.5–1 μmol/l) suitable for selective inhibition of NHE3. The changes in bioelectric activity strongly resembled the responses to hypercapnia (PCO₂: 60–100 mmHg). In BCECF-AM-loaded cultures a subfraction of ventrolateral VLNcs was found to be intracellularly acidified by 0.05–0.1 pH units following treatment with S1611; the time course of this acidification was similar to that evoked by hypercapnia. All drug effects were sustained and readily reversible upon washing. Non-CO₂/H⁺-responsive medullary neurones as well as hippocampal CA3 neurones were unaffected by up to 20 μmol/l S1611. It is concluded that the selective inhibition of NHE3 acidifies and activates CO₂/H⁺-sensitive neurones within the ventrolateral medulla oblongata. Received: 12 February 1999 / Received after revision and accepted: 15 April 1999     

Aldosterone actions on basolateral Na+/H+ exchange in Madin-Darby canine kidney cells

In recent studies, there has been a re-evaluation of the polarity of Na⁺/H⁺ exchange in Madin-Darby canine kidney (MDCK) cells. This study was designed to examine aldosterone actions on basolaterally located Na⁺/H⁺ exchange of MDCK cell monolayers grown on permeant filter supports; pH_i was analysed in the absence of bicarbonate by using the pH-sensitive fluorescent probe 2,7-bis(carboxyethyl)-5,6-carboxyfluorescein. Pre-exposure of MDCK cells to aldosterone led within 10–20 min to an alkalization of pH_i ( 0.3 pH unit); this effect is prevented by an addition of dimethylamiloride to the basolateral superfusate. Addition of aldosterone led to stimulation of the basolaterally located Na⁺/H⁺ exchange activity (Na⁺-dependent recovery from an acid load); this effect required preincubation (more then 3 min) and was observed at 0.1 nM aldosterone. Preexposure (15 min) of MDCK monolayers to phorbol 12-myristate 13-acetate also led to an activation of Na⁺/H⁺ exchange; pre-exposure to 8-bromo-cAMP led to inhibition of Na⁺/H⁺ exchange activity. An inhibitory effect of aldosterone was observed if Na⁺/H⁺ exchange activity was analysed in the presence of aldosterone; the highest inhibitory effects (20%–30%) occurred at concentrations of 5 nM and higher. Aldosterone-dependent inhibition does not require preincubation and is fully reversible; it was only observed at low (20 mM) but not at high Na⁺ concentrations (130 mM). The data suggest that aldosterone has an instantaneous inhibitory effect on basolaterally located Na⁺/H⁺ exchange activity under conditions of low Na⁺, but stimulates the rate of transport activity upon preincubation under conditions of physiological Na⁺ concentrations.     

Electrophysiological identification of principal and intercalated cells in the rabbit outer medullary collecting duct

Intracellular microelectrode techniques were used together with inhibitors of Na⁺ transport (amiloride) and H⁺ transport (acetazolamide and SITS¹) to identify principal cells and intercalated cells in the outer stripe of the rabbit outer medullary collecting duct. The principal cell (n=9) had a basolateral membrane voltage (V _bl) of –64.7±3.2 mV, a fractional resistance of the apical membrane (fR _a=R _a/R _a+R _bl) of 0.82±0.02, and a K⁺-selective basolateral membrane. Luminal amiloride hyperpolarizedV _bl by 10.3±2.1 mV and increasedfR _a to near unity (n=7). Bath acetazolamide and SITS were without effect on these parameters. The intercalated cell (n=5) had aV _bl of –25.0±3.2 mV, afR _a of 0.99±0.01, and a Cl^–-selective basolateral membrane. Bath acetazolamide or SITS hyperpolarizedV _bl by 26.4±8.2 mV. Luminal amiloride did not alterV _bl of this cell. The differential effects of the inhibitors also indicate that the principal and intercalated cells are probably not directly coupled electrically.     

Sorbitol metabolism in inner medullary collecting duct cells of diabetic rats

Intracellular accumulation of sorbitol, generated fromd-glucose via the aldose reductase pathway, is thought to play an important role in diabetic complications such as lens cataracts and neuropathy. In order to elucidate the effect of diabetes on the renal inner medulla, another sorbitol-rich tissue, male Wistar rats were treated with a single dose of streptozotocin (60 mg/kg body weight, i.p.). Six wecks later total inner medullary tissue (IM) or isolated inner medullary collecting duct (IMCD) cells were prepared. In diabetic IM tissue, sorbitol content was 1.8-fold higher than in control IM tissue (134±17 vs. 74±22 mol/g tissue protein). Sorbitol production in both normal and diabetic IMCD cells was strongly dependent on extracellulard-glucose concentration. In normal cells, for example, sorbitol production was 90±9 mol sorbitol/g protein x h at 45 mMd-glucose compared to 13±1 mol/g protein x h at 5 mM. At identicald-glucose concentrations sorbitol synthesis in diabetic IMCD cells was, however, always significantly higher than in control cells (122% of control at 15 mM and 126% of control at 45 mM). In addition, aldose reductase activity in diabetic IM was found to be augmented. The maximal velocity was 4.2 times higher (97±22 U/g protein vs. 23±7 U/g protein) while theK _m of the enzyme remained unchanged. Membrane permeability for sorbitol or the response to changes in extracellular osmolarity was not significantly different in diabetic IMCD cells and normal cells with correspondingly high intracellular sorbitol concentrations. Similarly the kinetic parameters ofd-glucose uptake were not altered by streptozotocin treatment. These results suggest that increased medullary sorbitol content in diabetic rats is a result of increased sorbitol synthesis due to a higher extracellulard-glucose concentration and augmented aldose reductase activity in face of an unaltered sorbitol permeability of the plasma membrane.     

S3226, a novel inhibitor of Na+/H+ exchanger subtype 3 in various cell types

 Inhibition of Na⁺/H⁺ exchange (NHE) subtypes has been investigated in a study of the mouse fibroblast L cell line (LAP1) transfected with human (h) NHE1, rabbit (rb) NHE2, rat (rt) or human (h) NHE3 as well as an opossum kidney cell line (OK) and porcine renal brush-border membrane vesicles (BBMV). S3226 {3-[2-(3-guanidino-2-methyl-3-oxo-propenyl)-5-methyl-phenyl]-N-isopropylidene-2-methyl-acrylamide dihydro-chloride} was the most potent and specific NHE3 inhibitor with an IC₅₀ value of 0.02 μmol/l for the human isoform, whereas its IC₅₀ value for hNHE1 and rbNHE2 was 3.6 and @80 μmol/l, respectively. In contrast, amiloride is a weak NHE3 inhibitor (IC₅₀>100 μmol/l) with a higher affinity to hNHE1 and rbNHE2. Cariporide (4-isopropyl-3-methylsulphonyl-benzoyl-guanidine methane-sulphonate), which has an IC₅₀ for NHE3 of approximately 1 mmol/l, is a highly selective NHE1 inhibitor (0.08 μmol/l). Therefore, S3226 is a novel tool with which to investigate the physiological and pathophysiological roles of NHE3 in animal models. Received: 14 May 1998 / Received after revision: 29 June 1998 / Accepted: 2 July 1998     

Activation of Ca2+-sensitive Cl– current by reverse mode Na+/Ca2+ exchange in rabbit ventricular myocytes

 We investigated how Ca²⁺-sensitive transient outward current, I _to(Ca), is activated in rabbit ventricular myocytes in the presence of intracellular Na⁺ (Na⁺ _i) using the whole-cell patch-clamp technique at 36°C. In cells dialysed with Na⁺-free solutions,the application of nicardipine (5 μM) to block L-type Ca²⁺ current (I _Ca) completely inhibited I _to(Ca). In cells dialysed with a [Na⁺]_i≥5 mM, however, I _to(Ca) could be observed after blockade of I _Ca, indicating the activity of an I _Ca-independent component. The amplitude of I _Ca-independent I _to(Ca) increased with voltage in a [Na⁺]_i-dependent manner. The block of Ca²⁺ release from the sarcoplasmic reticulum by caffeine, ryanodine or thapsigargin blocked I _Ca-independent I _to(Ca). In Ca²⁺-free bath solution I _to(Ca) was completely abolished. The application of 2 mM Ni²⁺ or the newly synthesized compound KBR7943, a selective blocker of the reverse mode of Na⁺/Ca²⁺ exchange, or perfusion with pipette solution containing XIP (10 μM), a selective blocker of the exchanger, blocked I _Ca-independent I _to(Ca). From these results we conclude that, in the presence of Na⁺ _i, I _to(Ca) can be activated via Ca²⁺-induced Ca²⁺ release triggered by Na⁺/Ca²⁺ exchange operating in the reverse mode after blockade of I _Ca. Received: 20 January 1998 / Received after revision: 6 July 1998 / Accepted: 25 July 1998