钙拮抗剂对高草酸尿导致的大鼠肾小管上皮细胞损伤的保护作用

Preventive effects of calcium antagonist on injury of renal tubular epithelial cells induced by hyperoxaluria

目的观察高草酸尿对大鼠肾小管上皮细胞内游离钙离子浓度([Ca2+]i)和细胞凋亡的影响,并了解钙拮抗剂硝苯地平对该影响的保护作用。方法60只雄性SD大鼠随机分成饮水组(只饮去离子水)、硝苯地平组(饮去离子水,并灌喂硝苯地平10mg.kg-1.d-1)、诱石组(饮1%乙二醇去离子水)、诱石+硝苯地平干预组(共3组,饮1%乙二醇去离子水,并分别灌喂硝苯地平3、6、10mg.kg-1.d-1),每组10只,连续处理4周。测定各组大鼠24h尿草酸浓度;TUNEL技术检测肾小管上皮细胞凋亡指数;应用Flou-3/AM荧光指示剂测定大鼠肾近曲小管细胞内Ca2+的荧光强度。结果诱石组和诱石+硝苯地平干预组24h尿草酸浓度均高于饮水组和硝苯地平组(P<0.01)。与饮水组相比,诱石组大鼠肾小管上皮细胞凋亡指数和肾小管上皮细胞内Ca2+荧光强度均明显增加(P<0.01)。诱石+硝苯地平(3、6、10mg.kg-1.d-1)干预组Ca2+荧光强度分别为诱石组的76.7%、62.7%和56.4%,量效关系显著(r=0.839,P<0.01)。肾小管上皮细胞内Ca2+荧光强度与肾小管上皮细胞凋亡指数密切相关(r=0.826,P<0.01)。结论高草酸尿可使大鼠肾小管上皮细胞[Ca2+]i及细胞凋亡水平显著增加,钙拮抗剂硝苯地平对此有明显的干预效果。

Objective To investigate the effects of hyperoxaluria on rat renal tubular epithelium intracellular calcium concentration （[Ca^2＋]i） and cell apoptosis, and explore the protective effects of calcium antagonist—nifedipine. Methods Sixty male SD rats were randomly divided into six groups （n=10）. Rats in water-drinking group were treated with deionized water, nifedipine group with deionized water and nifedipine 10 mg·kg^-1·d^-1, calculi-induced group with deionized water containing 1% ethylene glycol, and three calculi-induced＋nifedipine-intervening groups with deionized water containing 1% ethylene glycol plus nifedipine 3, 6 and 10 mg·kg^-1·d^-1, respectively. Four weeks later, the 24 h oxaluria concentration was measured, the apoptosis index of renal tubular epithelial cells was detected with TUNEL method, and Ca^2＋ fluorescence intensity of cells of renal proximal tubules was determined by flow cytometry using Fluo-3/AM staining. Results The 24 h oxaluria concentrations in calculi-induced group and calculi-induced＋nifedipine-intervening groups were higher than those in water-drinking group and nifedipine group （P〈0.01）. The apoptosis index and Ca^2＋ fluorescence intensity were significantly higher in calculi-induced group than those in water-drinking group （P〈0.01）. The Ca^2＋ fluorescence intensity in calculi-induced＋nifedipine （3, 6 and 10 mg·kg^-1·d^-1）-intervening groups was 76.7%, 62.7% and 56.4% of calculi-induced group, respectively, with a significant dose-effect relationship （r=0.839, P〈0.01）. The apoptosis index of renal tubular epithelial cells was significantly correlated with Ca^2＋ fluorescence intensity （r=0.826, P〈0.01）. Conclusion Hyperoxaluria can increase apoptosis and [Ca^2＋]i concentration of renal tubular epithelial cells in rats, and nifedipine can effectively protect renal tubular epithelial cells to resist hyperoxaluria.