Renin secretion from permeabilized juxtaglomerular cells requires a permeant cation

 The cytosolic concentration of chloride correlates directly with renin secretion from renal juxtaglomerular granular (JG) cells. In the present study, the mechanism by which chloride stimulates renin release was investigated in a preparation of permeabilized rat glomeruli with attached JG cells. An isosmotic increase in the concentration of chloride by 129 mM stimulated renin release 16- to 20-fold. Substitution of K⁺ by the impermeant cation N-methyl-d-glucamine (NMDG) abolished this response, while substitution with Na⁺ caused marginal inhibition. Substitution with Cs⁺ had no effect. Addition of sucrose, which permeates the secretory granules poorly, also abolished the stimulation of renin secretion by KCl. The response to KCl was not affected by K⁺-channel antagonists or by agonists of K⁺ channels. Chloride channel blockers were also without effect on the secretory response to KCl. When the ATP concentration was lowered from 1 to 0.1 mM renin release was stimulated, while an increase in the ATP concentration from 1 to 5 mM had no effect. Blockers of ATP-sensitive (K_ATP) channels did not modify the response to chloride. The present data suggest that chloride stimulates renin release after entry of KCl into the renin secretory granules which results in swelling and release of renin. Received: 3 July 1998 / Received after revision: 9 September 1998 / Accepted: 8 October 1998     

酸中毒致大鼠离体冠状动脉收缩的机制

目的:探讨细胞外酸中毒(pH_(ex)6.8)致大鼠离体冠状动脉(RCA)收缩的机制。方法:采用离体微血管张力法,通过观察Na~+-H~+交换体1(NHE-1)选择性抑制剂cariporide(HOE-642)或Na~+-HCO_3~-共同转运体(NBC)抑制剂S0859预孵对pH_(ex)6.8所致RCA收缩的影响,探讨酸碱转运体在酸中毒收缩RCA中的作用;通过观察氯通道抑制剂NPPB和尼氟酸(NFA)预孵及细胞外去除氯离子对pH_(ex)6.8所致RCA收缩的影响,探讨氯离子通道在酸中毒收缩RCA中的作用。结果:pH_(ex)6.8引起RCA静息张力升高,最大张力为(3.90±0.95)mN。30μmol/L HOE-642和100μmol/L S0859均抑制pH_(ex)6.8引起的RCA收缩(P0.01)。NPPB和NFA均呈浓度依赖性地抑制pH_(ex)6.8引起的RCA收缩和KCl(60 mmol/L)引起的收缩。100μmol/L的NPPB和NFA均抑制U46619(1μmol/L)引起的RCA收缩(P0.01)。等摩尔NaBr代替细胞外液中NaCl后,几乎完全抑制pH_(ex)6.8引起的RCA收缩(P0.01),但是对KCl(60 mmol/L)或U46619(1μmol/L)引起的RCA收缩无显著影响。结论:细胞外液酸化所致的RCA收缩与激活NHE-1和NBC及促进氯离子跨细胞膜运动有关。     

柠檬酸铁铵通过活性氧途径影响人丙型肝炎病毒的蛋白翻译

目的研究铁对HCV IRES依赖的病毒蛋白翻译的影响,以及其与细胞ROS活性变化的关系。方法以脂质体细胞转染法,将双荧光素酶报告基因表达载体p CI-Rluc-HCV IRES-Fluc转染人肝癌细胞系Huh-7细胞。在0、50和300μmol/L浓度的柠檬酸铁铵(FAC)作用24 h后,双荧光素酶报告基因检测系统检测HCV IRES依赖的病毒蛋白翻译的变化。ROS荧光染色方法检测细胞ROS活性变化,Western blot法检测细胞中Nrf2蛋白表达的变化。加入100μmol/L的DPI后,检测300μmol/L FAC实验组中HCV蛋白翻译的变化和细胞ROS的变化。结果与对照组相比,FAC增加了Huh-7细胞HCV IRES依赖的病毒蛋白翻译、增加了ROS活性,并且可以引起核转录因子Nrf2表达增加(P0.05)。加入ROS抑制剂DPI后,可以显著抑制FAC诱导的HCV IRES依赖的病毒蛋白翻译及Nrf2蛋白的表达(P0.05)。结论 FAC可以诱导细胞HCV IRES依赖的病毒蛋白翻译增加,可能与FAC促进Huh-7细胞产生过多的ROS有关。     

离子色谱法同时测定葡萄糖酸钙及其杂质(Cl-,SO42-)的含量

本文采用Waters ILC-1离子液相色谱仪,IC-PAK A50×4.6mm色谱柱,pH6.61×10^-3mol/L邻苯二甲酸溶液为流动相,430型电导检测器检测,由外标法和外标单点校正法同时测定了葡萄糖酸钙及其杂质(Cl^-,SO₄^2-)的含量。方法简便、快速,测定结果与中国药典法一致。外标法和外标单点校正法测定Cl^-,SO₄^2-的平均回收率为100.8%和100.2%,相关系数分别为0.9951(n=8)和0.9961(n=8)。     

鼻内镜下局部生理盐水注射治疗鼻出血

鼻利特尔区出血时选择有效、迅速、操作简便的治疗方法,对减轻患者痛苦和减少并发症十分重要。笔者对150例（176侧）鼻利特尔区出血的门诊病例采用生理盐水黏膜下注射方法治疗的效果进行观察,效果显著。现报道如下。     

S‐Gal®, A novel 1H MRI reporter for β‐galactosidase

Reporter genes and associated enzyme activity are becoming increasingly significant for research in vivo. The lacZ gene and β‐galactosidase (β‐gal) expression have long been exploited as reporters of biologic manipulation at the molecular level, and a noninvasive detection strategy based on proton MRI is particularly attractive. 3,4‐Cyclohexenoesculetin β‐D‐galactopyranoside (S‐Gal®) is a commercial histologic stain, which forms a black precipitate in the presence of β‐gal and ferric ions, suggesting potential detectability by MRI. Generation of the precipitate is now shown to cause strong T₂* relaxation, revealing β‐gal activity. A series of tests with the enzyme in vitro and with tumor cells shows that this approach can be used as an assay for β‐gal activity. Proof of principle is shown in human breast tumor xenografts in mice. Upon direct injection of a mixture of 3,4‐cyclohexenoesculetin β‐D‐galactopyranoside and ferric ammonium citrate, intense contrast was observed immediately in MCF7‐lacZ tumors, but not in wild‐type tumors. 3,4‐Cyclohexenoesculetin β‐D‐galactopyranoside activation in combination with ferric ions introduces a novel approach for assaying enzyme activity by MRI in vivo. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.     

顺铂激活的低分化鼻咽癌细胞氯电流

目的： 研究抗癌药顺铂对低分化鼻咽癌细胞（CNE-2Z）氯通道的激活作用以及该电流的特性。方法：采用膜片钳技术记录顺铂激活的CNE-2Z细胞全细胞电流;离子置换法等方法分析通道的特性。结果：细胞外灌流5 μmol/L的顺铂诱发CNE-2Z细胞产生一个有明显外向优势的电流,电流的翻转电位为(-6.69 ± 0.51) mV,接近氯离子平衡电位(-0.9 mV)。该电流的激活依赖于细胞内ATP。顺铂激活的细胞膜氯通道对阴离子的通透性顺序为：I-≥Br->Cl->gluconate。氯通道阻断剂tamoxifen完全抑制该电流。结论：抗癌药顺铂可以激活一个电流特征与容积激活性氯通道相似的氯通道。     

CFTR氯通道在硫化氢诱导的心肌保护及细胞增殖中的作用

目的： 探讨囊性纤维化跨膜传导调节因子（CFTR）氯通道在硫化氢（H2S）诱导的心肌保护及细胞增殖中的作用。方法：应用氯化钴（CoCl2）在大鼠H9c2心肌细胞建立化学性缺氧损伤心肌细胞实验模型;CCK-8试剂盒检测心肌细胞存活率;Hoechst 33342核染色法检测心肌细胞凋亡。结果：在400-2 000 μmol/L浓度范围内,CoCl2呈剂量依赖性地抑制H9c2心肌细胞的存活率,600 μmol/L CoCl2 能诱导H9c2心肌细胞产生明显的凋亡;在100-800 μmol/L浓度范围内,硫氢化钠（NaHS）呈剂量依赖性地促进H9c2心肌细胞增殖;NaHS能保护H9c2心肌细胞对抗CoCl2引起的细胞损伤作用,使细胞存活率升高,凋亡率降低;100 μmol/L CFTR氯通道拮抗剂5-硝基-2-（3-苯丙胺）-苯甲酸（NPPB)能明显地阻断NaHS对CoCl2的细胞毒性的抑制作用,但不能阻断NaHS抗心肌细胞凋亡作用及促进心肌细胞增殖作用。结论：CFTR氯通道可能参与H2S的抗CoCl2引起的心肌细胞毒性作用。     

The RND protein is involved in the vulnibactin export system in Vibrio vulnificus M2799

Vibrio vulnificus, an opportunistic marine bacterium that causes a serious, often fatal, infection in humans, requires iron for its pathogenesis. This bacterium exports vulnibactin for iron acquisition from the environment. The mechanisms of vulnibactin biosynthesis and ferric-vulnibactin uptake systems have recently been reported, while the vulnibactin export system has not been reported. Mutant growth under low-iron concentration conditions and a bioassay of the culture supernatant indicate that the VV1_0612 protein plays a crucial role in the vulnibactin secretion as a component of the resistance-nodulation-division (RND)-type efflux system in V. vulnificus M2799. To identify which RND protein(s) together with VV1_0612 TolC constituted the RND efflux system for vulnibactin secretion, deletion mutants of 11 RND protein-encoding genes were constructed. The growth inhibition of a multiple mutant (Δ11) of the RND protein-encoding genes was observed 6 h after the beginning of the culture. Furthermore, ΔVV1_1681 exhibited a growth curve that was similar to that of Δ11, while the multiple mutant except ΔVV1_1681 showed the same growth as the wild-type strain. These results indicate that the VV1_1681 protein is involved in the vulnibactin export system of V. vulnificus M2799. This is the first genetic evidence that vulnibactin is secreted through the RND-type efflux systems in V. vulnificus.     

顺铂激活的低分化鼻咽癌细胞氯电流为非钙激活氯电流*

 目的：探讨顺铂激活的低分化鼻咽癌细胞（CNE-2Z）氯通道电流是否为钙激活的氯电流。方法：采用膜片钳全细胞记录技术记录细胞内/外无Ca2+及钙通道阻断剂对顺铂激活氯电流的影响,并用高渗灌流液观察顺铂激活氯电流的容积敏感性。结果：去除细胞外液的Ca2+后,5 μmol/L顺铂能诱发氯电流,且电流大小与细胞外有Ca2+ 时无明显差异,但潜伏期与达峰时间延长。细胞内外均无Ca2+ 对顺铂激活氯电流未产生影响。钙通道阻断剂nifedipine未能抑制顺铂诱发的氯电流。但细胞外灌流高渗液几乎可完全抑制顺铂激活的氯电流。结论: 顺铂激活的氯通道开放不依赖于细胞内/外的Ca2+,该通道不是钙激活氯通道而很可能是容积敏感性氯通道。