Continuous Treatment with Oxalate Changes Renal Physiology and Morphology (DK0750

描述(申请人提供)：草酸在草酸钙(CaOx)肾钙化病和草酸导致的肾结石中所起的作用还不是很清楚。越来越多的证据表明，除了晶体形成外，草酸还通过与肾上皮、间质和血管系统的相互作用促进这些条件的形成。对这些影响的不同易感性可能部分解释了为什么具有相似风险因素的人没有类似的临床症状。这项提议将利用两个版本的小型泵模型来研究这些相互作用。标准的14D方案模拟中到重度高草酸尿，因为它导致草酸排泄和肾小管内CaOx-肾钙质沉着症增加大于或等于3倍。LongDose方案将模拟更常见的轻到中度高草酸尿症，方法是在4wk期间诱导草酸排泄量小于或等于1.5-2倍的增加，并诱导CaOx/CaOx混合肾钙沉积症。这项提议的一个新方面是，离子色谱和偏光显微镜/Yasue染色+形态计量学分析将被用于将草酸对肾单位、间质或血管的特定部分的影响与肾内草酸浓度和晶体沉积相关联。剂量反应和时间进程研究将确定这些变化发生在晶体沉积之前，因此可能促进肾钙质沉着。在具体目标1中，将确定360um Kox/24小时14D对肝功能、心肌病和骨重建的影响，并将开发LongDose方案。特定目标2将利用RT-PCR、Northern&Western印迹和免疫荧光来识别持续、稳定暴露于草酸的过程中，节段性、全身性、血管和结石疾病标志物表达的变化。特定目标3将利用透射电子显微镜和免疫荧光来识别在持续、稳定地暴露于草酸盐期间表现出形态损伤、细胞凋亡或增殖的肾单位节段以及间质和血管区域。与公共卫生的相关性：这项建议利用大鼠小腹痛模型研究了草酸盐在CaOx肾钙化病和草酸盐驱动的结石病早期阶段对肾脏特定区域的影响。我们的目标是确定那些促进这些条件的影响。未来的工作将确定这些影响的机制，目标是开发一种有效的预防性治疗。

DESCRIPTION (provided by applicant): The role that oxalate plays in calcium oxalate (CaOx) nephrocalcinosis and oxalate driven nephrolithiasis is not well understood. There is accruing evidence that in addition to crystal formation, oxalate promotes these conditions through its interactions with the renal epithelium, interstitium and vasculature. Differing susceptibilities to these effects may partially explain why individuals with similar risk factors have do not have similar clinical symptoms. This proposal will utilize two versions of the minipump model to study these interactions. The standard 14D protocol models moderate-to-severe hyperoxaluria in that it induces a greater than or equal to 3x increase in oxalate excretion and intratubular CaOx-nephrocalcinosis. The LongDose protocol will model the more common mild-to-moderate hyperoxaluria by inducing less than or equal to 1.5-2x increase in oxalate excretion over a 4wk period and the induction of mixed CaOx-/CaP- nephrocalcinosis. A novel aspect of this proposal is that ion chromatography and polarizing microscopy/ Yasue staining + morphometric analysis will be used to correlate oxalate's effects on specific segments of the nephron, interstitium or vasculature with intrarenal oxalate concentrations and crystal deposition. Dose response and time course studies will identify those changes which occur prior to crystal deposition and thus could be fostering nephrocalcinosis. In Specific Aim 1, the effects of 360 muM KOx/24hr for 14D on liver function, cardiomyopathy, and bone remodiling will be determined and the LongDose protocol will be developed. Specific Aim 2 will utilize RT-PCR, Northern & Western blotting and immunofluorescence to identify changes in the expression of segment specific, general distress, vasculature distress and stone disease makers during continuous, steady exposure to oxalate. Specific Aim 3 will utilize transmission electron microscopy and immunofluorescence to identify segments of the nephron and regions of the interstitium and vasculature that show morphological damage, apoptosis or proliferation during continuous, steady exposure to oxalate. Relevance to Public Health: This proposal investigates oxalate's effects on specific regions of the kidney during the early phases of CaOx- nephrocalcinosis and oxalate driven stone disease using the rat minipump model. The objective is to identify those effects which promote these conditions. Future work will determine the mechanism of these effects with the goal of developing an effective preventative therapy.