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. Author manuscript; available in PMC: 2017 Aug 1.
Published in final edited form as: Ann N Y Acad Sci. 2016 Jul 21;1378(1):80–86. doi: 10.1111/nyas.13156

Figure 4.

Figure 4

Menadione redox cycling inhibits parathion metabolism. (A) Human liver microsomes were treated with 20 µM parathion (PT) in the absence and presence of 50 µM menadione. At the indicated times, reactions were assayed for paraoxon. Data are mean ± SE (n= 3). Asterisks show that the formation of paraoxon in the presence of menadione was significantly different (P < 0.05) from that in the absence of menadione. (B) The ability of menadione to reverse the inhibitory effects of parathion on AChE activity in reactions with human liver microsomes. Reactions containing human liver microsomes were supplemented with AChE. Incubations with parathion inhibited AChE activity, and this was reversed by menadione. The figures show that menadione redox cycling readily inhibited paraoxon formation. Each point is the mean ± SE (n = 3). Asterisks show that the inhibition of AChE in the presence of menadione was significantly different (p < 0.05) from that in the absence of menadione. Summary of data from Ref. 36.