NADP+ biosynthesis by rats receiving a pellagragenic diet.
Rats showing signs of pellagra-like disease associated with gelatin ingestion were injected with [14C]-nicotinic acid into the portal vein and the incorporation of the label into hepatic NAD+ and NADP+ was determined. The quantity of NADP+ synthesized within 1 h after [14C]-nicotinic acid injection by the experimental group, supplemented or not with dietary niacin, was 75% lower than that synthesized by the control group fed a casein control diet (141 nmol h-1 g-1). The NAD+ and NADP+ contents of the liver of the experimental animals were 245 and 93 micrograms/g liver, respectively, i.e., significantly lower than those for the controls (597 and 210 micrograms/g, respectively). Dietary supplementation with niacin increased the NAD+ content to 317 micrograms/g liver but had no statistical effect on NADP+ content (75 micrograms/g liver) or NADP+ synthesis (46.5 in the free niacin group vs 37.0 nmol h-1 g-1 in the niacin-supplemented group). Therefore, NAD+ content did not seem to limit NADP+ synthesis. These results suggest that the lower availability of NADP+ is responsible, at least in part, for some metabolic derangements in pellagra-like disease, such as a decrease in the activity of NADP(+)-dependent enzymes observed in quail muscle.
Alencar
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Departamento de Bioquímica e Imunologia, Universidade Fedral de Minas Gerais, Belo Horizonte, Brasil.
Moraes-Santos
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D000818:Animals; D008099:Liver / Q000378:metabolism*; D008297:Male; D009243:NAD / Q000096:biosynthesis; D009249:NADP / Q000096:biosynthesis*; D009525:Niacin / Q000008:administration & dosage / Q000378:metabolism; D010383:Pellagra / Q000378:metabolism*; D011897:Random Allocation; D051381:Rats
D009243:NAD; D009525:Niacin; D009249:NADP