左旋单甲基精氨酸对大鼠肾小球清蛋白通透性的影响

Effects of L-NMMA on Albumin Permeability of Isolated Rat Glomeruli

目的探讨一氧化氮(NO)合成酶抑制药对大鼠体外肾小球清蛋白通透性的影响及可能的作用机制。方法用标准筛技术游离正常雄性SD大鼠肾小球,应用视频显微术通过肾小球体积变化计算肾小球清蛋白的通透性(Palb)。大鼠体外肾小球分别与不同浓度(0.5,1.0,2.0 mmol.L-1)NO-单甲基-L-精氨酸(L-NMMA)培养30 min;与2.0 mmol.L-1L-NMMA培养不同时间(15,30,45 min)。体外肾小球与2.0 mmol.L-1L-NMMA及500μmmol.L-1NO供体diethylenetriamine NONOate(DETA NONOate)培养45 min;与2.0 mmol.L-1L-NMMA及5 mmol.L-1超氧化物歧化酶(SOD)培养45 min。观察不同情况下Palb。结果与对照组比较,大鼠体外肾小球与0.5 mmol.L-1L-NMMA培养30 min对Palb无明显影响,与1.0或2.0 mmol.L-1L-NMMA培养导致Palb显著增加(P<0.01),且2.0 mmol.L-1L-NMMA对Palb影响更为显著。体外肾小球与2.0 mmol.L-1L-NMMA培养15,30,45 min,Palb均较对照组明显增加(均P<0.01),且随时间延长Palb逐渐增加,培养45 min时Palb最大。体外肾小球与L-NMMA及DETA NONOate一起培养45 min,Palb无明显增加;与L-NMMA及SOD一起培养45 min,Palb亦无明显增加。结论 NO是肾小球清蛋白滤出的调节因子,生成减少导致Palb增加,过氧化物活性可能参与NO合成酶抑制药引起的清蛋白排泄增加。

Objective To investigate the effect and potential mechanism of nitric oxide（NO） synthase inhibitior on albumin permeability（Palb） of isolated rat glomeruli. Methods Glomeruli of normal male Sprague-Dawley rats was isolated with the standard sieve.Palb was calculated by measuring the volume change of isolated glomeruli by using videomicroscopy.Isolated rat glomeruli were incubated with various concentrations of NG-monomethyl-L-arginine（L-NMMA）（0.5,1.0,2.0 mmol·L-1） for 30 min,with 2.0 mmol·L-1 L-NMMA for 15,30,45 min,respectively.Glomeruli were incubated with 2.0 mmol·L-1 L-NMMA and 500 μmol·L-1 DETA NONOate for 45 min.Glomeruli were incubated with 2.0 mmol·L-1 L-NMMA and 5 mmol·L-1 superoxide dismutase（SOD） for 45 min,and were observed for the change of Palb under different conditions. Results 0.5 mmol·L-1 L-NMMA had no obvious effect on Palb,whereas 1.0 mmol·L-1,2.0 mmol·L-1 L-NMMA casused a significant increase of Palb as compared to that of control group（P0.01）.The effect of 2.0 mmol·L-1 of L-NMMA on Palb increased further than that of 1.0 mmol·L-1.A significant increase in Palb was observed at concentration of 2.0 mmol·L-1 L-NMMA incubated with glomeruli for 15,30,45 min（vs control,P0.01）,respectively with incubated time lasting,Palb increased gradually.The maximal of Palb was obtained by incubation for 45 min.The increase of Palb was blocked in rat glomeruli with L-NMMA and DETA NONOate for 45 min.Palb in rat glomeruli was not affected with 2.0 mmol·L-1 L-NMMA and SOD. Conclusion NO is a regulatory factor in glomerular permeability to albumin,depletion of which resulting in an increase in Palb.The bioavailability of superoxide may be involved in the increases of Palb by NO synthase inhibitior.