Criddle David N, Gillies Stuart, Baumgartner-Wilson Heidi K, Jaffar Mohammed, Chinje Edwin C, Passmore Sarah, Chvanov Michael, Barrow Stephanie, Gerasimenko Oleg V, Tepikin Alexei V, Sutton Robert, Petersen Ole H
MRC Secretory Research Group, Department of Physiology and Division of Surgery and Oncology, University of Liverpool, Liverpool L69 3BX, United Kingdom.
J Biol Chem. 2006 Dec 29;281(52):40485-92. doi: 10.1074/jbc.M607704200. Epub 2006 Nov 6.
Oxidative stress may be an important determinant of the severity of acute pancreatitis. One-electron reduction of oxidants generates reactive oxygen species (ROS) via redox cycling, whereas two-electron detoxification, e.g. by NAD(P)H:quinone oxidoreductase, does not. The actions of menadione on ROS production and cell fate were compared with those of a non-cycling analogue (2,4-dimethoxy-2-methylnaphthalene (DMN)) using real-time confocal microscopy of isolated perfused murine pancreatic acinar cells. Menadione generated ROS with a concomitant decrease of NAD(P)H, consistent with redox cycling. The elevation of ROS was prevented by the antioxidant N-acetyl-l-cysteine but not by the NADPH oxidase inhibitor diphenyliodonium. DMN produced no change in reactive oxygen species per se but significantly potentiated menadione-induced effects, probably via enhancement of one-electron reduction, since DMN was found to inhibit NAD(P)H:quinone oxidoreductase detoxification. Menadione caused apoptosis of pancreatic acinar cells that was significantly potentiated by DMN, whereas DMN alone had no effect. Furthermore, bile acid (taurolithocholic acid 3-sulfate)-induced caspase activation was also greatly increased by DMN, whereas DMN had no effect per se. These results suggest that acute generation of ROS by menadione occurs via redox cycling, the net effect of which is induction of apoptotic pancreatic acinar cell death. Two-electron detoxifying enzymes such as NAD(P)H:quinone oxidoreductase, which are elevated in pancreatitis, may provide protection against excessive ROS and exert an important role in determining acinar cell fate.
氧化应激可能是急性胰腺炎严重程度的一个重要决定因素。氧化剂的单电子还原通过氧化还原循环产生活性氧（ROS），而双电子解毒，例如通过NAD(P)H：醌氧化还原酶进行的解毒，则不会产生ROS。使用分离的灌注小鼠胰腺腺泡细胞的实时共聚焦显微镜，比较了甲萘醌对ROS产生和细胞命运的影响与非循环类似物（2,4-二甲氧基-2-甲基萘（DMN））的影响。甲萘醌产生ROS，同时NAD(P)H减少，这与氧化还原循环一致。抗氧化剂N-乙酰-L-半胱氨酸可阻止ROS的升高，但NADPH氧化酶抑制剂二苯基碘鎓则不能。DMN本身不会改变活性氧，但会显著增强甲萘醌诱导的效应，可能是通过增强单电子还原，因为发现DMN会抑制NAD(P)H：醌氧化还原酶解毒。甲萘醌导致胰腺腺泡细胞凋亡，DMN可显著增强这种凋亡，而单独的DMN则没有作用。此外，胆汁酸（牛磺石胆酸3-硫酸盐）诱导的半胱天冬酶激活也因DMN而大大增加，而DMN本身没有作用。这些结果表明，甲萘醌通过氧化还原循环急性产生活性氧，其净效应是诱导胰腺腺泡细胞凋亡死亡。在胰腺炎中升高的双电子解毒酶，如NAD(P)H：醌氧化还原酶，可能提供针对过量ROS的保护，并在决定腺泡细胞命运中发挥重要作用。
