Division of Nephrology and Hypertension, Georgetown University Medical Center, 6 PHC, Suite F6003, 3800 Reservoir Rd, NW, Washington DC 20007, USA.
Hypertension. 2010 Sep;56(3):498-504. doi: 10.1161/HYPERTENSIONAHA.110.152959. Epub 2010 Aug 9.
Asymmetrical dimethylarginine inhibits nitric oxide synthase, cationic amino acid transport, and endothelial function. Patients with cardiovascular risk factors often have endothelial dysfunction associated with increased plasma asymmetrical dimethylarginine and markers of reactive oxygen species. We tested the hypothesis that reactive oxygen species, generated by nicotinamide adenine dinucleotide phosphate oxidase, enhance cellular asymmetrical dimethylarginine. Incubation of rat preglomerular vascular smooth muscle cells with angiotensin II doubled the activity of nicotinamide adenine dinucleotide phosphate oxidase but decreased the activities of dimethylarginine dimethylaminohydrolase by 35% and of cationic amino acid transport by 20% and doubled cellular (but not medium) asymmetrical dimethylarginine concentrations (P<0.01). This was blocked by tempol or candesartan. Cells stably transfected with p22(phox) had a 50% decreased protein expression and activity of dimethylarginine dimethylaminohydrolase despite increased promoter activity and mRNA. The decreased DDAH protein expression and the increased asymmetrical dimethylarginine concentration in p22(phox)-transfected cells were prevented by proteosomal inhibition. These cells had enhanced protein arginine methylation, a 2-fold increased expression of protein arginine methyltransferase-3 (P<0.05) and a 30% reduction in cationic amino acid transport activity (P<0.05). Asymmetrical dimethylarginine was increased from 6+/-1 to 16+/-3 micromol/L (P<0.005) in p22(phox)-transfected cells. Thus, angiotensin II increased cellular asymmetrical dimethylarginine via type 1 receptors and reactive oxygen species. Nicotinamide adenine dinucleotide phosphate oxidase increased cellular asymmetrical dimethylarginine by increasing enzymes that generate it, enhancing the degradation of enzymes that metabolize it, and reducing its cellular transport. This could underlie increases in cellular asymmetrical dimethylarginine during oxidative stress.
不对称二甲基精氨酸抑制一氧化氮合酶、阳离子氨基酸转运和内皮功能。心血管危险因素患者常伴有内皮功能障碍，血浆中不对称二甲基精氨酸和活性氧标志物增加。我们检验了这样一个假设，即烟酰胺腺嘌呤二核苷酸磷酸氧化酶产生的活性氧增强细胞不对称二甲基精氨酸。血管紧张素 II 孵育大鼠前肾小球血管平滑肌细胞可使烟酰胺腺嘌呤二核苷酸磷酸氧化酶活性增加一倍，但使二甲基精氨酸二甲氨基水解酶活性降低 35%，阳离子氨基酸转运活性降低 20%，并使细胞（而非培养基）中不对称二甲基精氨酸浓度增加一倍（P<0.01）。这一作用被替米沙坦或坎地沙坦所阻断。尽管 p22(phox) 稳定转染的细胞启动子活性和 mRNA 增加，但二甲基精氨酸二甲氨基水解酶的蛋白表达和活性却降低了 50%。p22(phox) 转染细胞中的 DDAH 蛋白表达减少和不对称二甲基精氨酸浓度增加可被蛋白酶体抑制所阻止。这些细胞的蛋白精氨酸甲基化增加，蛋白精氨酸甲基转移酶-3 的表达增加了 2 倍（P<0.05），阳离子氨基酸转运活性降低了 30%（P<0.05）。p22(phox) 转染细胞中的不对称二甲基精氨酸从 6+/-1 增加到 16+/-3 micromol/L（P<0.005）。因此，血管紧张素 II 通过 1 型受体和活性氧增加细胞内不对称二甲基精氨酸。烟酰胺腺嘌呤二核苷酸磷酸氧化酶通过增加生成不对称二甲基精氨酸的酶、增强代谢该酶的酶的降解以及减少其细胞转运，来增加细胞内不对称二甲基精氨酸。这可能是氧化应激时细胞内不对称二甲基精氨酸增加的基础。
