Studies on the rate of incorporation of tryptophan into nicotinamide-adenine dinucleotides in rats chronically exposed to carbon disulphide.

Previous experiments have revealed changes in the metabolism of nieotinic acid and nicotinamide-adenine dinucleotides due to CS₂ intoxication. In this study the incorporation of tryptophan into nicotinamide-adenine dinucleotides in the liver of rats chronically intoxicated with CS₂ has been measured. The concentration and radioactivity of NAD in the liver of rats were determined 5 hr after administration of a loading dose of tryptophan and 2 hr after injection of a trace dose of [¹⁴C]tryptophan. It was found that tryptophan was more extensively incorporated into nucleotides in the liver of rats intoxicated with CS₂. This indicates, that tryptophan, rather than nicotinic acid, is the main precursor of NAD synthesis in animals intoxicated with CS₂.