Schmidt K, List B M, Klatt P, Mayer B
Institut für Pharmakologie und Toxikologie, Karl-Franzens-Universität Graz, Austria.
J Neurochem. 1995 Apr;64(4):1469-75. doi: 10.1046/j.1471-4159.1995.64041469.x.
In the present study we investigated uptake of the nitric oxide (NO) synthase inhibitors NG-methyl-L-arginine and NG-nitro-L-arginine by the mouse neuroblastoma x rat glioma hybrid cell line NG108-15. Uptake of NG-methyl-L-arginine was characterized by biphasic kinetics (Km1 = 8 mumol/L, Vmax1 = 0.09 nmol x mg-1 x min-1; Km2 = 229 mumol/L, Vmax2 = 2.9 nmol x mg-1 x min-1) and was inhibited by basic but not by neutral amino acids. Uptake of NG-nitro-L-arginine followed Michaelis-Menten kinetics (Km = 265 mumol/L, Vmax = 12.8 +/- 0.86 nmol x mg-1 x min-1) and was selectively inhibited by aromatic and branched chain amino acids. Further characterization of the transport systems revealed that uptake of NG-methyl-L-arginine is mediated by system y+, whereas systems L and T account for the transport of NG-nitro-L-arginine. In agreement with these data on uptake of the inhibitors, L-lysine and L-ornithine antagonized the inhibitory effects of NG-methyl-L-arginine on bradykinin-induced intracellular cyclic GMP accumulation, whereas L-tryptophan, L-phenylalanine, and L-leucine interfered with the effects of NG-nitro-L-arginine. These data suggest that rates of uptake are limiting for the biological effects of NO synthase inhibitors.
在本研究中，我们调查了小鼠神经母细胞瘤x大鼠胶质瘤杂交细胞系NG108 - 15对一氧化氮（NO）合酶抑制剂NG - 甲基 - L - 精氨酸和NG - 硝基 - L - 精氨酸的摄取情况。NG - 甲基 - L - 精氨酸的摄取表现为双相动力学（Km1 = 8 μmol/L，Vmax1 = 0.09 nmol·mg⁻¹·min⁻¹；Km2 = 229 μmol/L，Vmax2 = 2.9 nmol·mg⁻¹·min⁻¹），且被碱性氨基酸而非中性氨基酸所抑制。NG - 硝基 - L - 精氨酸的摄取遵循米氏动力学（Km = 265 μmol/L，Vmax = 12.8 ± 0.86 nmol·mg⁻¹·min⁻¹），并被芳香族和支链氨基酸选择性抑制。对转运系统的进一步表征显示，NG - 甲基 - L - 精氨酸的摄取由y⁺系统介导，而L系统和T系统负责NG - 硝基 - L - 精氨酸的转运。与这些抑制剂摄取的数据一致，L - 赖氨酸和L - 鸟氨酸拮抗了NG - 甲基 - L - 精氨酸对缓激肽诱导的细胞内环鸟苷酸积累的抑制作用，而L - 色氨酸、L - 苯丙氨酸和L - 亮氨酸则干扰了NG - 硝基 - L - 精氨酸的作用。这些数据表明，摄取速率限制了NO合酶抑制剂的生物学效应。
