Saito Kieko, Yoshioka Hisashi
Institute for Environmental Sciences, University of Shizuoka, Japan.
Free Radic Res. 2002 Feb;36(2):143-9. doi: 10.1080/10715760290006457.
We have previously suggested that the spin trap agent, N-tert-butyl-alpha-phenylnitrone (PBN) can function not only as an antioxidant but also as a nitric oxide (NO) donor. To characterize the pharmacological activities of PBN against oxidative damage, we examined the effect of PBN on NO generation under hyperoxic conditions. The formation of NO in mice exposed to 95% oxygen was determined using a NOx analyzer and electron spin resonance (ESR). Levels of NOx, an oxidative product of NO, increased in the blood of mice under these conditions. However, the increase was returned to a normal level by the NOS (nitric oxide synthase) inhibitor, L-NMMA, indicating that the NO was formed via a biosynthetic pathway. In addition, ESR spectra of the liver and brain of control and experimental mice that were measured using Fe(DETC)2 as an NO trap reagent showed strong ESR signals from NO complexes in the livers of mice exposed to 95% oxygen. When examining the effect of PBN in mice, PBN reduced the NOx formation in the blood under the same hyperoxic conditions. In addition, the ESR intensity of the NO complex was weaker in the PBN-treated mice than in the non-treated mice, showing that PBN possess anti-inflammatory properties. However, under a normal atmosphere, NOx and ESR analyses showed that NO levels increased in PBN-treated mice but not in control mice. These findings suggested that PBN functions as an NO donor under specific physiological conditions. PBN appears to protect against hyperoxia-induced NO toxicity by anti-inflammatory action rather than by serving as an NO donor.
我们之前曾提出，自旋捕捉剂N-叔丁基-α-苯基硝酮（PBN）不仅可以作为抗氧化剂发挥作用，还可以作为一氧化氮（NO）供体。为了表征PBN对氧化损伤的药理活性，我们研究了PBN在高氧条件下对NO生成的影响。使用NOx分析仪和电子自旋共振（ESR）测定暴露于95%氧气的小鼠体内NO的形成。在这些条件下，小鼠血液中NO的氧化产物NOx水平升高。然而，通过NOS（一氧化氮合酶）抑制剂L-NMMA可使该升高恢复至正常水平，这表明NO是通过生物合成途径形成的。此外，以Fe(DETC)2作为NO捕捉剂对对照小鼠和实验小鼠的肝脏和大脑进行ESR光谱测定，结果显示暴露于95%氧气的小鼠肝脏中来自NO复合物的ESR信号很强。在研究PBN对小鼠的影响时，PBN在相同的高氧条件下可减少血液中NOx的形成。此外，PBN处理组小鼠中NO复合物的ESR强度比未处理组小鼠弱，表明PBN具有抗炎特性。然而，在正常大气条件下，NOx和ESR分析表明，PBN处理组小鼠体内NO水平升高，而对照小鼠则未升高。这些发现表明，PBN在特定生理条件下起NO供体的作用。PBN似乎是通过抗炎作用而非作为NO供体来预防高氧诱导的NO毒性。
