Endogenous methylarginines regulate neuronal nitric-oxide synthase and prevent excitotoxic injury
Endogenous methylarginines regulate neuronal nitric-oxide synthase and prevent excitotoxic injury
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DOI：
10.1074/jbc.m108983200
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发表时间：
2002-09-13
影响因子：
4.8
通讯作者：
Zweier, JL
中科院分区：
文献类型：
--
作者：
Cardounel, AJ;Zweier, JL
一氧化氮（NO）在神经元功能中具有关键作用;然而，高水平导致细胞损伤。虽然胍基甲基化精氨酸（MA）包括不对称二甲基精氨酸（ADMA）和N-G-甲基-L-精氨酸（NMA）是一氧化氮合酶（NOS）的有效竞争性抑制剂，并且在蛋白质降解时释放，但尚不清楚它们的细胞内浓度是否足以关键地调节神经元NO产生和次级细胞功能或损伤。因此，我们确定内源性神经元MA浓度及其对神经元NOS功能和兴奋性毒性损伤的影响。动力学研究表明，K。对于L-精氨酸，K-i值为2.38 μ m，V-max为0.229 μ mol mg（-1）min（-1），而对于ADAIA和NMA，K-i值分别为0.67 μ m和0.50 μ m。所有NOS抑制MA的正常神经元浓度被确定为约15 μ m，而L-精氨酸浓度约为90 μ m。这些MA水平导致> 50%的从神经元NOS产生NO的抑制。下调或上调这些神经元MA水平，分别显着增强或抑制NO介导的兴奋性毒性损伤。因此，神经元MA深刻地调节NOS功能并抑制NO介导的损伤。这些内源性NOS抑制剂的水平的药理学调节提供了一种新的方法来调节神经元功能和损伤。
Nitric oxide (NO) has a critical role in neuronal function; however, high levels lead to cellular injury. While guanidino-methylated arginines (MA) including asymmetric dimethylarginine (ADMA) and N-G-methyl-L-arginine (NMA) are potent competitive inhibitors of nitric oxide synthase (NOS) and are released upon protein degradation, it is unknown whether their intracellular concentrations are sufficient to critically regulate neuronal NO production and secondary cellular function or injury. Therefore, we determine the intrinsic neuronal MA concentrations and their effects on neuronal NOS function and excitotoxic injury. Kinetic studies demonstrated that the K. for L-arginine is 2.38 mum with a V-max of 0.229 mumol mg(-1) min(-1), while K-i values of 0.67 mum and 0.50 mum were determined for ADAIA and NMA, respectively. Normal neuronal concentrations of all NOS-inhibiting MA were determined to be approximate to15 mum, while L-arginine concentration is approximate to90 mum. These MA levels result in > 50% inhibition of NO generation from neuronal NOS. Down-modulation or up-modulation of these neuronal MA levels, respectively, dramatically enhanced or suppressed NO-mediated excitotoxic injury. Thus, neuronal MA profoundly modulate NOS function and suppress NO mediated injury. Pharmacological modulation of the levels of these intrinsic NOS inhibitors offers a novel approach to modulate neuronal function and injury.