Nicotinamide nucleotides in the erythrocytes of patients suffering from pellagra.

1. The nicotinamide nucleotide concentrations in the erythrocytes of subjects suffering from pellagra (pellagrins) were not lower than those in normal subjects, but the ability of erythrocytes to synthesize these nucleotides in vitro was significantly lower in pellagrins. 2. The oral administration of 10g. of l-leucine daily for 5 days depressed the nicotinamide nucleotide-synthesizing ability of erythrocytes both in normal subjects and in pellagrins. This was not accompanied by changes in the nucleotide concentration in erythrocytes. 3. Quinolinic acid brought about a significant inhibition of the synthesis of nicotinamide nucleotides in vitro. Such inhibition was partially overcome by increasing the concentration of nicotinic acid in the medium.