Renal NaCl Delivery and ROS Production in mTAL

项目1假设Dahl盐敏感(SS)大鼠在喂食高盐饮食时将重新吸收更多的 肾髓质厚升支(MTAL)中的NaCI高于正常量，这反过来将刺激 过量产生活性氧(ROS)，从而减少骨髓血流量(MBF)。这个 SS大鼠mTAL表达的Na/K/2CI共转运体数量高于盐不敏感对照SS.13大鼠 并将确定它们是否也表达更多的Na/H交换器(NHE)的异构体 可以解释过多的超氧化物(O*2~)的产生。我们建议增加NaCI的腔内释放 外髓间质NaCI浓度的增加可刺激NAD(P)H氧化酶和 增加O*2“和H_2O_2的产生。将确定O‘2~~和/或H_2O_2是否从 在生物利用度降低的情况下mTAL对直肠血管周细胞的影响以及这是否会导致 降低MBF。这些事件将使用时间分辨荧光视频显微镜进行研究 髓组织条。这些观察结果的生理学相关性将通过《意识》杂志的研究来评估。 仪表化的老鼠。延髓间质O‘2~、H202、NO和髓质间质的动态测量 将使用植入的微渗析纤维获得[NaCI]。延髓血流和动脉的变化 每天将使用植入的光纤和激光多普勒测量这些清醒大鼠的压力 在食盐(NaCI)摄入量增加之前和之后进行动脉导管留置 高血压的发展。该项目由三个具体目标确定：1)确定是否暴露于 通过管状微灌流和/或浴池灌流增加NaCI可导致更大的mTAL SS中O*2“或H_2O_2的产生以及随后周围血管的收缩 对照SS.13BN大鼠；2)探讨NaCI增加腔内转运的细胞机制 MTAL和间质NaCI浓度增加促进SS大鼠0*2“产生；3)表征 清醒SS大鼠肾髓质产生O*2“、H_2O_2和NO的时间反应 如果ROS增加，则会导致NACI摄入量增加后髓内血流量减少。

Project 1 hypothesizes that Dahl salt-sensitive (SS) rats when fed a high salt diet will reabsorb greater than normal amounts of NaCI in the renal medullary thick ascending limb (mTAL) that in turn will stimulate excess production of reactive oxygen species (ROS) and thereby reduce medullary blood flow (MBF). The mTAL of SS rats express greater amounts of Na/K/2CI co-transporter than salt-insensitive control SS.13 rats and it will be determined if they also express greater amounts of isoforms of the Na/H exchanger (NHE) that could account for excess superoxide (O*2~) production. We propose that increased luminal delivery of NaCI together with increases of outer medullary interstitial NaCI concentration may stimulate NAD(P)H oxidase and enhance production of O*2" and H2O2. It will be determined if greater diffusion of O'2~ and/or H2O2 occurs from mTAL to vasa recta pericytes in the presence of reduced NO bioavailability and whether this leads to a reduction of MBF. These events will be studied using time resolved fluorescence videomicroscopy of medullary tissue strips. Physiological relevance of these observations will be assessed by studies in conscious instrumented rats. Sequential measurements of medullary interstitial O'2~, H202, NO and medullary interstitial [NaCI] will be obtained using implanted microdialysis fibers. Changes of medullary blood flow and arterial pressure will be measured daily in these conscious rats using implanted optical fibers and laser-Doppler techniques together with indwelling arterial catheters before and following an increase in salt (NaCI) intake and the development of hypertension. The project is defined by three specific aims: 1) To determine if exposure of mTAL to increased NaCI by either tubular microperfusion and/or bath superfusion results in greater mTAL production of O*2" or H2O2 and subsequent constriction of surrounding vasa recta vessels in SS compared to the control SS.13BN rats; 2) To explore the cellular mechanisms whereby increased luminal delivery of NaCI to mTAL and increases of interstitial NaCI concentrations enhance 0*2" production in SS rats; 3) To characterize the temporal responses of renal medullary production of O*2", H2O2, and NO in conscious SS rats to determine if increases in ROS initiate reductions of medullary blood flow following increased NaCI intake.