Renal Function In Transgenic Mice

转基因小鼠的肾功能

基本信息

批准号：
8349776
负责人：
Jurgen Schnermann
金额：
$ 112.42万
依托单位：
NATIONAL INSTITUTE OF DIABETES AND DIGESTIVE AND KIDNEY DISEASES
依托单位国家：
美国
项目类别：
财政年份：
资助国家：
美国
起止时间：
至
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/8349776
关键词：
Affect Agonist Angiotensin II Angiotensin Receptor Angiotensins Animals Benefits and Risks Blood Glucose Blood Pressure Blood Vessels Body Fluids Calcium Carrier Proteins Cells Data Defect Diabetes Mellitus Distal Diuresis Equilibrium Excretory function Exhibits FVB Mouse Feedback Filtration Genes Glomerular Capillary Glomerular Filtration Rate Glucose Glucose Transporter Goals Growth Henle&apos s loop Hypertension Individual Infection Infusion procedures Kidney Link Liquid substance Macula densa Magnesium Maintenance Measures Mediating Micropuncture Modality Mouse Strains Mus Mutagenesis Mutant Strains Mice Mutation Natriuresis Nephrons Neuraxis Nonsense Mutation P2X-receptor Pathogenesis Pathway interactions Patients Phenotype Phosphoenolpyruvate Carboxylase Physiological Plasma Proteins Proximal Kidney Tubules Purinergic P2 Receptors Receptor Activation Receptor Signaling Regulatory Pathway Renal function Research Resistance Risk Role Signal Transduction Sodium Sodium Chloride Streptozocin Suramin System Testing Therapeutic Transgenic Mice Tubular formation Vascular resistance Vasoconstrictor Agents Water Wild Type Mouse absorption capillary bed carbene diabetes management diabetic glomerular filtration glycemic control improved in vivo inhibitor/antagonist mortality mouse model mutant novel pressure prevent promoter protein function pyridoxal phosphate-6-azophenyl-2&apos ,4&apos -disulfonic acid receptor recombinase response salt intake tool urinary vasoconstriction

项目摘要

1. Tubuloglomerular feedback (TGF), the change of afferent arteriolar resistance initiated by changes of luminal NaCl concentration, is thought to be related to NaCl-dependent release of ATP by macula densa cells. We have explored the possibility that the released ATP may directly interact with vasoconstrictor P2 purinergic receptors in the vicinity of the glomerular vascular pole by determining the stop flow pressure (PSF) response to a saturating increase in loop of Henle flow rate before and during the i.v. administration of the P2 receptor inhibitors PPADS (12 mg/kg + 35 mg/kg hr) or suramin (50 mg/kg + 150 mg/kg hr) in two different strains of wild type mice (SWR/J and FVB). Both agents significantly reduced the blood pressure response to the P2X agonist z-methylene ATP indicating effective blockade of vascular P2 receptors. In both strains of mice, elevating flow to 30 nl/min reduced PSF by 16.4 2.2 % and 17.1 1.8 %. During infusion of PPADS PSF fell by 18.8 2 % (p=0.4) and 16.5 1.5 % (p=0.82) in the two strains of mice. During suramin infusion PSF decreased by 14.7 2.4 % (p=0.62) and 15 1.3 % (p=0.4) in SWR/J and FVB mice respectively. Including PPADS (10-4 M) in the loop perfusate did not significantly alter the PSF response (18.9 1.8 %; p=0.54). Arterial blood pressure was not systematically affected by the P2 inhibitors. Interestingly, PPADS significantly reduced proximal tubular fluid reabsorption both in fractional and absolute terms as measured by free flow micropuncture. These results indicate that the direct activation of P2 purinergic receptors by ATP is not a major cause of TGF-induced vasoconstriction in vivo. Furthermore, ATP appears to mediate stimulation of proximal tubular fluid reabsorption through P2 receptor activation. 2. Inhibition of glucose reabsorption along the renal proximal tubule is actively being considered as a treatment modality for the reduction of blood glucose in diabetic conditions. However, the physiologic consequences of inhibition of tubular glucose reabsorption are unclear. We have used a novel mouse model generated by N-ethyl-Nnitrosurea (ENU) mutagenesis that carries a nonsense mutation in the Na-linked glucose transporter gene Slc5a2 resulting in loss of transporter protein function. The phenotype of SP mutants is characterized by higher urinary excretion of calcium, magnesium and protein with retarded growth. Studies of kidney function revealed constant glomerular filtration rates and well maintained proximal tubular fluid reabsorption. The prominent diuresis without enhanced natriuresis appears to be generated along the distal nephron by osmotic overload. Following the administration of streptozotocin to induce diabetes, mutants exhibited better overall glycemic control than wild type mice. However, there was a somewhat higher infection risk and an exaggerated mortality rate in mutant animals. Nevertheless, the phenotype of SGLT2 mutants is markedly similar to patients who carry mutations in the Scl5a2 gene making these mice a useful new tool to examine the long-term benefits and risks associated with inhibition of SGLT2 for the management of diabetes. 3. Defects in excretion of salt and water by the kidney appear to be the final common pathway in the pathogenesis of arterial hypertension, but this issue has remained controversial in that recent studies have suggested critical contributions of other systems including the vasculature and central nervous system. We have tested whether selective inhibition of proximal tubular NaCl reabsorption can cause hypertension. Since reabsorption of NaCl and water in the proximal tubule is under the tonic stimulatory control of angiotensin II, we have examined whether disruption of angiotensin II actions has a critical and non-redundant role in determining the level of blood pressure. Disruption of AT1 angiotensin receptor signaling in the proximal tubule was produced by deleting floxed angiotensin receptors with cre recombinase under control of the PEPCK promoter. Mutant mice had a significant lowering of arterial blood pressure, despite intact vascular responses. Micropuncture studies showed that elimination of this pathway reduced proximal fluid reabsorption and altered the expression of key sodium transporters. Our data confirm that selective reduction of salt transport in the proximal tubule is sufficient to affect blood pressure suggesting that targeting of reabsorptive functions of the proximal tubule of the kidney should be a useful therapeutic strategy in hypertension.

1。肾小管反馈（TGF），是腔内NaCl浓度变化引发的传入小动脉抗性的变化，被认为与macula densa细胞对NaCl依赖性ATP释放有关。我们已经探讨了释放的ATP可以通过确定对I.V之前和期间Henle流量饱和的饱和量增加的肾小球血管极附近的血管收缩P2 P2嘌呤能受体相互作用。在两种不同菌株的野生型小鼠（SWR/J和FVB）中给药P2受体抑制剂PPAD（12 mg/kg + 35 mg/kg HR）或苏拉明蛋白（50 mg/kg + 150 mg/kg/kg HR）。两种药物都显着降低了对P2X激动剂Z-甲基ATP的血压反应，表明有效阻断了血管P2受体。在两种小鼠菌株中，将流动升高到30 nl/min均降低了PSF 16.4 2.2％和17.1 1.8％。在注入PPAD的过程中，PSF在两种小鼠菌株中下降了18.8 2％（P = 0.4）和16.5 1.5％（P = 0.82）。在Suramin输注期间，PSF分别降低了14.7 2.4％（P = 0.62）和15 1.3％（P = 0.4），分别为SWR/J和FVB小鼠。在环形灌注液中包括PPAD（10-4 m）没有显着改变PSF响应（18.9 1.8％； P = 0.54）。动脉血压不受P2抑制剂的系统影响。有趣的是，PPAD显着降低了近端管状液的重吸收，无论是通过自由流动型测量的分数和绝对项。这些结果表明，通过ATP直接激活P2嘌呤能受体并不是TGF诱导的体内血管收缩的主要原因。此外，ATP似乎通过P2受体激活介导近端管状液的刺激。 2。沿肾近端小管的葡萄糖重吸收的抑制作用被视为在糖尿病条件下还原血糖的一种治疗方式。然而，抑制管状葡萄糖重吸收的生理后果尚不清楚。我们已经使用了由N-乙基 - 硝基尿素（ENU）诱变产生的新型小鼠模型，该诱变在Na连接的葡萄糖转运蛋白基因SLC5A2中带有废话，从而导致转运蛋白蛋白函数的丧失。 SP突变体的表型的特征是钙，镁和蛋白质的尿液排泄较高，生长迟缓。肾功能的研究表明，恒定的肾小球滤过率和维持良好的近端管状液。没有增强纳地尿液的突出的利尿作用似乎是通过渗透超负荷沿远端肾单位产生的。在施用链蛋白酶诱导糖尿病之后，突变体比野生型小鼠表现出更好的总血糖控制。但是，突变动物的感染风险和夸张的死亡率较高。然而，SGLT2突变体的表型明显与携带SCL5A2基因突变的患者显着相似，使这些小鼠成为检查与抑制SGLT2对糖尿病管理的长期益处和风险的有用新工具。 3.肾脏排泄盐和水的缺陷似乎是动脉高血压发病机理中的最终常见途径，但是这个问题仍然存在争议，因为最近的研究表明，包括脉管系统和中枢神经系统在内的其他系统的重要贡献。我们已经测试了对近端管状NaCl重吸收的选择性抑制是否会导致高血压。由于近端小管中NaCl和水的重吸收在血管紧张素II的刺激性控制下，因此我们研究了血管紧张素II作用的破坏在确定血压水平中是否具有关键和非冗余作用。通过在PEPCK启动子控制的CRE重组酶的控制下删除Floxed血管紧张素受体，从而产生了近端小管中AT1血管紧张素受体信号传导的破坏。尽管有完整的血管反应，但突变小鼠的动脉血压显着降低。微题研究表明，消除该途径可降低近端流体吸收并改变关键钠转运蛋白的表达。我们的数据证实，近端小管中盐转运的选择性减少足以影响血压，这表明靶向肾脏近端小管的重吸收功能应该是高血压中的一种有用的治疗策略。