A comparative study on the effects of disulfiram, cyanamide and 1-aminocyclopropanol on the acetaldehyde metabolism in rats.

1-aminocyclopropanol (ACP) is a potent inhibitor of aldehyde dehydrogenase (ALDH) in vivo and in vitro. Like cyanamide it has a rapid onset of action in vivo with the highest inhibition occurring after 2--24 hrs. and a long duration of action like disulfiram with measurable inhibition after 144 hrs. All the three inhibitors decreased the activity of the mitochondrial low-Km ALDH strongly in vivo, however, in markedly different doses. Cyanamide inhibited the high-Km ALDH only in vivo, whereas in vitro, the hihgh-Km ALDH was unaffected by cyanamide but significantly inhibited by disulfiram and ACP. The inhibition produced by the inhibitors appeared to be irreversible. Acetaldehyde protected the low-Km enzyme at different extents depending on the inhibitor used. The inhibition of ALDH in intoxicated and control rats and its relation to acetaldehyde oxidation and the disulfiram-ethanol reaction are discussed.