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71.
高尿酸血症大鼠肾小管上皮细胞OAT3表达的变化 总被引:3,自引:5,他引:3
目的 研究高尿酸血症状态下Wistar大鼠肾小管上皮细胞有机阴离子转运体3(OAT3)表达水平的变化.方法 20只雄性Wistar大鼠随机分为对照组和高尿酸血症组,高尿酸血症组饲以高酵母饲料并给予腺嘌呤100 mg/(kg·d)灌胃,定期监测大鼠血尿酸、肌酐、尿素氮水平,应用免疫组织化学技术检测大鼠肾脏近端小管上皮细胞OAT3的表达水平.结果 实验第14天,高尿酸血症组大鼠血尿酸水平显著高于对照组(t′=-15.00,P<0.01);高尿酸血症组OAT3的吸光度值较对照组明显降低(t=3.299,P<0.01),灰度值较对照组明显升高(t=-3.337,P<0.01).结论 高尿酸血症大鼠肾小管上皮细胞中OAT3 蛋白表达水平显著降低,OAT3可作为研发治疗高尿酸血症药物作用靶点. 相似文献
72.
Stornetta RL Rosin DL Wang H Sevigny CP Weston MC Guyenet PG 《The Journal of comparative neurology》2003,455(4):499-512
The pre-B?tzinger complex (pre-B?tC) is a physiologically defined group of ventrolateral medullary neurons that plays a central role in respiratory rhythm generation. These cells are located in a portion of the rostral ventrolateral medulla (RVLM) that is difficult to identify precisely for lack of a specific marker. We sought to determine whether somatostatin (SST) might be a marker for this region. The rat pre-B?tC area was defined as a 500-microm-long segment of ventrolateral medulla coextensive with the ventral respiratory group. This region was identified by juxtacellular labeling of neurons with respiratory-related activity and by its location rostral to the phrenic premotor neurons. It contained most of the SST-ir neuronal somata of the RVLM. These cells were small (107 microm(2)) and expressed high levels of preprosomatostatin mRNA. They were strongly neurokinin 1 receptor (NK1R)-ir and were selectively destroyed by saporin conjugated with an NK1R agonist (SSP-SAP). Most SST-ir neurons (>90%) contained vesicular glutamate transporter 2 (VGLUT2) mRNA, and terminals immunoreactive for SST and VGLUT2 protein were found in their midst. Few SST-ir neurons contained GAD-67 mRNA (<1%) or preproenkephalin mRNA (6%). Retrograde labeling experiments demonstrated that over 75% of the SST-ir neurons project to the contralateral pre-B?tC area, but none projects to the spinal cord. In conclusion, the RVLM contains many neurons that express preprosomatostatin mRNA. A subgroup of these cells contains high levels of SST and NK1R immunoreactivity in their somata. These glutamatergic interneurons identify a narrow region of the RVLM that appears to be coextensive with the pre-B?tC of adult rats. 相似文献
73.
It has been generally accepted that rod photoreceptor cells in the mammalian retina make synaptic contact with only a single population of rod bipolar cells, whereas cone photoreceptors contact a variety of cone bipolar cells. This assumption has been challenged in rodents by reports of a type of cone bipolar cell which receives input from both rods and cones. Questions remained as to whether similar pathways are present in other mammals. We have used an antiserum against the glutamate transporter GLT1-B to visualize a population of cone bipolar cells in the cat retina which make flat contacts with axon terminals of both rod and cone photoreceptor cells. These cells are identified as OFF-cone bipolar cells and correspond morphologically to type cb1 (CBa2) cone bipolar cells which are a major source of input to OFF-beta ganglion cells in the cat retina. The GLT1-B transporter was also localized to processes making flat contacts with photoreceptor terminals in rat and rabbit retinas. Examination of tissue processed for the GluR1 glutamate receptor subunit showed that cb1 cone bipolar cells, like their rodent counterparts, express this alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-selective receptor at their contacts with rod spherules. Thus, a direct excitatory pathway from rod photoreceptors to OFF-cone bipolar cells appears to be a common feature of mammalian retinas. 相似文献
74.
Understanding and controlling hepatobiliary function 总被引:1,自引:0,他引:1
Elferink RP 《Best Practice & Research: Clinical Gastroenterology》2002,16(6):1869-1034
Over the past decade, enormous progress has been made in identifying the mechanisms that underlie hepatobiliary excretion. A set of transport proteins mediates the canalicular transport of most important bile constituents. With the discovery of these transporter genes, the mechanism of bile formation could be partly elucidated and genetic defects caused by mutations in these genes identified. This progress is crucial not only for paediatric and adult hepatology, but also for pharmacology, because the characterization of these transport systems provides tools for the prediction of the pharmacokinetics of drugs. Indeed, there is a growing interest on the part of the pharmaceutical industry for research into transport systems in general and hepatobiliary secretion in particular. For all of these transporter genes, knockout mice have been bred that allow one to assess the in vivo function of each of these transporters with regard to their role in physiology and drug elimination. 相似文献
75.
Uptake of biocytin and biotin was investigated in cultured transformed variants of neuronal (NB2a neuroblastoma) and glial (C6 astrocytoma) CNS cells. NB2a cells took up both compounds but biocytin was transported more efficiently than biotin in the nanomolar concentration range. In NB2a cells a single transport mechanism was found for biocytin with different kinetic parameters in the presence of high extracellular Na+ (Km 0.4 microM, Vmax 20 pmol/min/mg), K+ (Km 1.7 microM, Vmax 32 pmol/min/mg), or choline+ (Km 0.1 microM, Vmax 5 pmol/min/mg). Two transport systems (Km1 17 microM, Vmax1 53 pmol/min/mg; Km2 314 microM, Vmax2 360 pmol/min/mg) were identified for biotin with only system 1 being Na+-dependent. Biocytin uptake was competitively inhibited by excess biotin but not vice versa. Inhibition studies with structural analogs indicated different specificities for biotin and biocytin uptake. Biocytin uptake into C6 cells was hardly detectable whereas biotin was taken up by diffusion (kD 0.6 microl/min/mg) and a single saturable mechanism (Km 70 microM, Vmax 119 pmol/min/mg) at high extracellular Na+. High extracellular K+ enhanced biotin diffusion into C6 cells. Inhibition studies with structural analogs revealed a less specific biotin uptake mechanism in C6 than in NB2a cells. Biocytin normalized deficient biotin-dependent propionyl-CoA carboxylase activity within 4 h in biotin-deficient NB2a cells whereas in C6 cells reactivation was <20% thereby confirming that biocytin is only poorly transported into C6 cells. Specific biocytin uptake into NB2a cells is to our knowledge the first demonstration of a carrier-mediated transport mechanism for this compound. Neuronal biocytin uptake might contribute to the pathogenesis of biotinidase deficiency where biocytin is present in elevated levels. 相似文献
76.
Glutamatergic post-synaptic receptors are closely related to the known excitotoxic effects of high doses of L-glutamate. Several behavioral abnormalities, glial reaction, and an increase of expression of the NMDA receptor sub-units have been observed in the rat hippocampus after early monosodium glutamate exposure. Thus, a quantitative morphological study was carried out to determine the effects of early exposure to monosodium glutamate on post-synaptic structures that mediate glutamate excitatory neurotransmission in the hippocampal CA1 field. Four milligrams per gram body weight of monosodium glutamate was subcutaneously injected into neonatal Wistar rats, at 1, 3, 5, and 7 days. Cell loss and several cytoarchitectonic parameters were evaluated in pyramidal cells from the hippocampal CA1 field in the treated rats at 60 days of age. An untreated group of rats were used as controls. Cell number in the hippocampus of experimental rats was 11.5% less than that in control animals. In addition, both dendritic arborization and dendritic spine density were adversely affected, and thin and mushroom-shaped spines became proportionally more numerous, while the opposite occurred to stubby spines. These results strongly suggest the occurrence of cell death and also show some cytoarchitectural modifications in the surviving neurons. These could lead to functional alterations in the hippocampal integrative activity, due to an early cytoexcitotoxic effect of monosodium glutamate. 相似文献
77.
Christopher J. Endres Peng Hsiao Francisco S. Chung Jashvant D. Unadkat 《European journal of pharmaceutical sciences》2006,27(5):501-517
Transport proteins play an important role in the adsorption, distribution and elimination of a wide variety of drugs. Therefore, it is not surprising that transporter-based drug interactions can occur in the clinic. These interactions can lead to changes in toxicity and/or efficacy of the affected drug. Here, we review such interactions and ask if these interactions could have been predicted from in vitro data. Conducting such in vitro–in vivo correlation is important for predicting future transporter-based drug interactions. 相似文献
78.
目的研究谷氨酸-天冬氨酸转运体(glutamate—aspartate transporters,GLAST)在正常豚鼠耳蜗内的分布,为探讨GLAST在防止耳蜗谷氨酸(Glu)神经毒性中的作用提供形态学基础。方法选取健康红目豚鼠6只,采用免疫组织化学方法,以山羊抗GLAST抗体为标记物,观察正常豚鼠耳蜗中GLAST的表达及分布。结果在正常豚鼠耳蜗的内、外毛细胞,内、外毛细胞周围的支持细胞,螺旋神经节细胞,血管纹边缘细胞和螺旋缘上皮,均有GLAST阳性表达。结论GLAST在正常豚鼠耳蜗内主要分布于内、外毛细胞,内、外毛细胞周围的支持细胞,螺旋神经节细胞、血管纹边缘细胞和螺旋缘上皮,其功能尚需进一步的研究。 相似文献
79.
80.
谷氨酸的兴奋毒性是造成视网膜神经节细胞损伤和死亡的主要因素之一,而谷氨酸转运体对维持细胞外谷氨酸水平起重要作用。GLAST是表达在Muller细胞膜上的一种重要的谷氨酸转运体,其在分子和蛋白质水平上的调节方式可能为酶底物—诱导的负反馈调节。 相似文献