Influence of urine pH on accurate urinary protein determination in Sprague-Dawley rats

BACKGROUND: Rat urinary protein concentration is commonly measured during safety assessment studies to evaluate potential drug-induced nephrotoxicity. It has been reported that impregnated reagent test strips (dipsticks) can yield false-positive urinary protein results for alkaline urine samples. OBJECTIVE: The objective of this study was to determine if urinary dipsticks accurately assess protein concentrations, especially in alkaline rat urine. METHODS: Ten male Sprague-Dawley rats were treated with 2% sodium bicarbonate and 2% ammonium chloride to alkalinize and acidify the urine, respectively. Urine pH was measured in treated and control rats using a pH meter and urinary dipsticks with the Clinitek 500. Quantitative urinary protein results were compared to urinary dipstick protein evaluations obtained with the Clinitek 500 and sulfosalicylic acid precipitation test methods. RESULTS: The urinary dipstick pH measurement had a very high correlation (r = .98) with the pH meter technique. Samples with alkaline pH (>or=7.5) analyzed for protein by dipstick analysis were in complete agreement 34.7% of the time with the quantitative technique, which was very similar to the 39.3% agreement for samples with neutral and acidic pH (相似文献   

AMPK-mTOR-ULK1-mediated autophagy protects carbon tetrachloride-induced acute hepatic failure by inhibiting p21 in rats

Autophagy is a lysosomal-dependent degradation pathway in eukaryotic cells. Recent studies have reported that autophagy can facilitate the activation of hepatic stellate cells (HSCs) and fibrogenesis of the liver during long-term carbon tetrachloride (CCl₄) exposure. However, little is known about the role of autophagy in CCl₄-induced acute hepatic failure (AHF). This study aimed to identify whether modulation of autophagy can affect CCl₄-induced AHF and evaluate the upstream signaling pathways mediated by CCl₄-induced autophagy in rats. The accumulation of specific punctate distribution of endogenous LC3-II, increased expression of LC3-II, Atg5, and Atg7 genes/proteins, and decreased expression of p62 gene were observed after acute liver injury was induced by CCl₄ in rats, indicating that CCl₄ resulted in a high level of autophagy. Moreover, loss of autophagic function by using chloroquine (CQ, an autophagic inhibitor) aggravated liver function, leading to increased expression of p21 (a cyclin-dependent kinase inhibitor) in CCl₄-treated rats. Furthermore, the AMPK-mTORC1-ULK1 axis was found to serve a function in CCl₄-induced autophagy. These results reveal that AMPK-mTORC1-ULK1 signaling-induced autophagy has a protective role in CCl₄-induced hepatotoxicity by inhibiting the p21 pathway. This study suggests a useful strategy aimed at ameliorating CCl₄-induced acute hepatotoxicity by autophagy.     

丁酸钠通过AMPK通路调控LPS造成牛乳腺上皮细胞脂代谢紊乱的作用机制

通过向脂多糖（LPS）诱导牛乳腺上皮细胞系（MAC-T）脂代谢紊乱模型中添加不同浓度（2、8、16 μmol·L^-1）的丁酸钠,探讨其对细胞脂代谢的调控机理及炎症损伤的修复作用。分别用1 000 ng·mL^-1 LPS刺激MAC-T细胞9 h后,检测细胞脂滴面积及三酰甘油（TG）含量;用不同浓度的丁酸钠刺激MAC-T细胞12 h后,流式细胞术检测细胞凋亡率;试验共分为5组：对照组、LPS处理组、2 μmol·L^-1丁酸钠+LPS处理组、8 μmol·L^-1丁酸钠+LPS处理组和16 μmol·L^-1丁酸钠+LPS处理组,分别对细胞TG含量、AMPK信号通路蛋白、脂代谢关键基因以及相关炎症因子进行检测。结果显示：LPS会造成MAC-T细胞总脂滴面积显著下降（P<0.05）,TG含量极显著下降（P<0.01）;不同浓度的丁酸钠对MAC-T细胞凋亡率没有影响;与对照组相比,LPS处理组TG含量极显著下降（P<0.01）、P-AMPK表达水平显著上升（P<0.05）、脂合成代谢相关基因ACC、SCD-1以及FAS mRNA表达水平均显著（P<0.05）或极显著（P<0.01）下降、脂分解代谢相关基因CPT-1、CPT-2以及ACO mRNA表达水平均显著上升（P<0.05）、炎症因子TNF-α和IL-6含量显著上升（P<0.05）;与LPS处理组相比,（2、8、16 μmol·L^-1）丁酸钠+LPS处理组TG含量有一定程度上升,P-AMPK表达水平下降,脂合成代谢相关基因表达水平上升,脂分解代谢相关基因表达水平有一定程度下降,炎症因子TNF-α和IL-6含量下降。本研究表明丁酸钠会通过AMPK通路激活脂合成代谢,调控TG的合成,并且对MAC-T细胞的炎症损伤具有一定的缓解作用。