Selective inhibition of complex I of the brain electron transport system by tetrahydroisoquinoline

The effects of 1,2,3,4-tetrahydroisoquinoline on the enzyme-protein complexes in the electron transport system were studied in mitochondria isolated from mouse brains. Tetrahydroisoquinoline significantly inhibited the activity of NADH-ubiquinone reductase, but had no effect on the activities of succinate-ubiquinone reductase, dihydroubiquinone-cytochrome c reductase, or ferrocytochrome c-oxygen reductase. The biochemical properties of tetrahydroisoquinoline in this study were quite similar to those of the dopaminergic neurotoxin 1-methyl-4-phenylpyridinium ion.