NAD+ biosynthesis from tryptophan in the presence of nicotinic acid or vice versa by rat hepatocytes--effect of clofibrate-feeding.
NAD+ biosynthesis from tryptophan in the presence of nicotinic acid or vice versa by rat hepatocytes was investigated. In the control hepatocytes, NAD+ synthesis from tryptophan was not affected by nicotinic acid from 0.026 to 0.26 mM. NAD+ synthesis from nicotinic acid was slightly inhibited with varying concentrations of tryptophan from 0.1 to 1.0 mM. In the clofibrate-treated hepatocytes, NAD+ synthesis from tryptophan was greatly increased (234% of the control), while that from nicotinic acid was decreased (71.2% of the control). Both, NAD+ synthesis from tryptophan and that from nicotinic acid were decreased by the coexisting nicotinic acid or tryptophan. Total amount of NAD+ synthesized from tryptophan and nicotinic acid at their physiological concentrations was significantly higher than that in the control hepatocytes as a result of a large increase of NAD+ synthesized from tryptophan. When the metabolic flux of 0.1 or 0.5mM tryptophan was investigated, the glutarate pathway was suppressed in the clofibrate-treated hepatocytes, the quinolinic acid-NAD+ flux being elevated. Similarly to clofibrate, DEHP and CPP revealed an increase in NAD+ synthesis from tryptophan. Mutual relationship of NAD+ biosyntheses from tryptophan and nicotinic acid in rat hepatocytes is discussed and the relevance with peroxisomal proliferation is suggested.
Shin
M
M
School of Pharmacy, Kobe Gakuin University, Japan.
Nakakita
S
S
Hashimoto
C
C
Sano
K
K
Umezawa
C
C
D000818:Animals; D001692:Biological Transport; D002994:Clofibrate / Q000494:pharmacology*; D005977:Glutarates / Q000378:metabolism; D006867:Hydrolases / Q000378:metabolism; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008830:Microbodies / Q000187:drug effects; D009243:NAD / Q000096:biosynthesis*; D009525:Niacin / Q000378:metabolism* / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D014364:Tryptophan / Q000378:metabolism* / Q000494:pharmacology
D005977:Glutarates; D009243:NAD; D009525:Niacin; D014364:Tryptophan; D006867:Hydrolases; C021480:kynureninase; C035736:glutaric acid; D002994:Clofibrate