脂多糖对大鼠近端肾小管一氧化氮合酶活性的影响。

Effect of lipopolysaccharide on nitric oxide synthase activity in rat proximal tubules.

作者信息

Mayeux P R, Garner H R, Gibson J D, Beanum V C

机构信息

Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock 72205.

出版信息

Biochem Pharmacol. 1995 Jan 6;49(1):115-8. doi: 10.1016/0006-2952(94)00449-v.

DOI:10.1016/0006-2952(94)00449-v

PMID:7530953

Abstract

Renal proximal tubules isolated from the rat possess nitric oxide synthase (NOS) activity that is calcium/calmodulin dependent and stereoselectively inhibited by NG-monomethyl-arginine (NMMA). In the absence of added Ca2+ and calmodulin, activity was reduced 84 +/- 13% compared with the activity in the presence of 2 mM Ca2+ and 25 micrograms/mL calmodulin. Inhibition by EGTA (10 mM) was 95 +/- 5% and by calmidazolium (R24571, 250 microM) was 99 +/- 1%. Inhibition by L-NMMA (100 microM) was 78 +/- 13% and by D-NMMA (100 microM) was 7 +/- 7%. The majority of NOS activity was found in the soluble fraction. NOS activity in isolated proximal tubules was also examined 6 hr after a single i.v. injection of lipopolysaccharide. Activity was increased significantly (P < 0.05) in the soluble fraction by 2-fold [from 0.320 +/- 0.052 to 0.648 +/- 0.046 (nmol/mg protein/30 min)] and in the particulate fraction by 3-fold [from 0.081 +/- 0.030 to 0.256 +/- 0.034 (nmol/mg protein/30 min)]. All activities were inhibited by EGTA. These data demonstrate that proximal tubules express a calcium/calmodulin-dependent NOS activity that is increased in vivo by lipopolysaccharide.

摘要

从大鼠分离出的肾近端小管具有一氧化氮合酶（NOS）活性，该活性依赖于钙/钙调蛋白，并被NG-单甲基精氨酸（NMMA）立体选择性抑制。在没有添加Ca2+和钙调蛋白的情况下，与存在2 mM Ca2+和25微克/毫升钙调蛋白时的活性相比，活性降低了84±13%。EGTA（10 mM）的抑制率为95±5%，钙调素（R24571，250 microM）的抑制率为99±1%。L-NMMA（100 microM）的抑制率为78±13%，D-NMMA（100 microM）的抑制率为7±7%。大部分NOS活性存在于可溶性部分。在单次静脉注射脂多糖6小时后，也检测了分离的近端小管中的NOS活性。可溶性部分的活性显著增加（P<0.05），增加了2倍[从0.320±0.052增加到0.648±0.046（nmol/毫克蛋白质/30分钟）]，颗粒部分的活性增加了3倍[从0.081±0.030增加到0.256±0.034（nmol/毫克蛋白质/30分钟）]。所有活性均被EGTA抑制。这些数据表明，近端小管表达一种依赖于钙/钙调蛋白的NOS活性，该活性在体内可被脂多糖增加。