Antioxidant protection of NO-induced relaxations of the mouse anococcygeus against inhibition by superoxide anions, hydroquinone and carboxy-PTIO

摘要

1 The potential protective effect of several antioxidants [Cu/Zn superoxide dismutase (Cu/Zn SOD), ascorbate, reduced glutathione (GSH), and α-tocopherol (α-TOC)] on relaxations of the mouse anococcygeus muscle to nitric oxide (NO; 15 μM) and, where appropriate, nitrergic field stimulation (10 Hz; 10 s trains) was investigated. 2 The superoxide anion generating drug duroquinone (100 μM) reduced relaxations to exogenous NO by 54 ± 6%; this inhibition was partially reversed by Cu/Zn SOD (250 u ml~(-1)), and by ascorbate (500 μM). Following inhibition of endogenous Cu/Zn SOD activity with diethyldithiocarbamate (DETCA), duroquinone (50 μM) also reduced relaxations to nitrergic field stimulation (by 53±6%) and this effect was again reversed by Cu/Zn SOD and by ascorbate. Neither GSH (500 μM) nor α-TOC (400 μM) afforded any protection against duroquinone.