Liu X, Miller S M, Szurszewski J H
Department of Physiology and Biophysics, Mayo Clinic, Rochester, MN 55905, USA.
J Auton Nerv Syst. 1997 Feb 17;62(3):126-33. doi: 10.1016/s0165-1838(96)00113-0.
This study examined in the rat anococcygeus muscle the tissue distribution of copper zinc superoxide dismutase, the activity of CuZn SOD, and the role of CuZn SOD in protecting nitric oxide from destruction by superoxide anion. Immunohistochemical studies revealed intense staining for CuZn SOD in neuronal nitric oxide synthase-containing nerves. Muscle strips contained 1081 +/- 300 units SOD g-1 wet tissue (mean +/- S.E.M., n = 5). Diethyldithiocarbamate (2 mM) inhibited CuZn SOD activity in supernatant fractions of muscle homogenates by 34% (P < 0.01, n = 5), an effect reversed by CuCl2 (2 mM). In control conditions, electrical field stimulation of nitrergic inhibitory nerves evoked a 61.5 +/- 10.5% (n = 10) relaxation against guanethidine (30 microM)-induced tone. Relaxation evoked by nitrergic inhibitory nerves was neither potentiated by exogenous CuZn SOD (10-1000 U ml-1) nor reduced by the O-2-generator, pyrogallol (30 microM). When diethyldithiocarbamate (2 mM) was present, stimulation of nitrergic inhibitory nerves evoked a 51.7 +/- 10.8% (P < 0.05, n = 10) relaxation against guanethidine (30 microM)-induced tone. Addition of pyrogallol (30 microM) to diethyldithiocarbamate-treated (2 mM for 30 min) muscle strips further reduced nerve-evoked relaxation to 30.7 +/- 7.6% (P < 0.01, n = 10). The inhibitory effect of pyrogallol was reversed by exogenous CuZn SOD (100 U ml-1). Diethyldithiocarbamate (2 mM) had no effect on relaxation evoked by exogenous NO (1 microM). The data indicate that CuZn SOD is present in rat anococcygeus muscle, that it is colocalized with nNOS in the nitrergic nerves, and that it protects NO from destruction by O-2.
本研究检测了大鼠肛门尾骨肌中铜锌超氧化物歧化酶的组织分布、铜锌超氧化物歧化酶（CuZn SOD）的活性，以及CuZn SOD在保护一氧化氮免受超氧阴离子破坏中的作用。免疫组织化学研究显示，含神经元型一氧化氮合酶的神经中CuZn SOD染色强烈。肌条含1081±300单位超氧化物歧化酶/克湿组织（平均值±标准误，n = 5）。二乙基二硫代氨基甲酸盐（2 mM）使肌肉匀浆上清液中的CuZn SOD活性抑制34%（P<0.01，n = 5），CuCl2（2 mM）可逆转此效应。在对照条件下，对含氮能抑制性神经进行电场刺激可引起相对于胍乙啶（30 μM）诱导张力61.5±10.5%（n = 10）的舒张。含氮能抑制性神经引起的舒张既不被外源性CuZn SOD（10 - 1000 U/ml）增强，也不被O₂生成剂邻苯三酚（30 μM）降低。当存在二乙基二硫代氨基甲酸盐（2 mM）时，对含氮能抑制性神经进行刺激引起相对于胍乙啶（30 μM）诱导张力51.7±10.8%（P<0.05，n = 10）的舒张。向用二乙基二硫代氨基甲酸盐处理（2 mM，30分钟）的肌条中加入邻苯三酚（30 μM）可使神经诱发的舒张进一步降低至30.7±7.6%（P<0.01，n = 10）。邻苯三酚的抑制作用可被外源性CuZn SOD（100 U/ml）逆转。二乙基二硫代氨基甲酸盐（2 mM）对外源性一氧化氮（1 μM）引起的舒张无影响。数据表明，CuZn SOD存在于大鼠肛门尾骨肌中，它与含氮能神经中的神经元型一氧化氮合酶共定位，并且它保护一氧化氮不被O₂破坏。
