Concentration dependent promoting effects of sodium L-ascorbate with the same total dose in a rat two-stage urinary bladder carcinogenesis.
Sodium L-ascorbate (Na-AsA) has been demonstrated to be a strong promoter of rat urinary bladder tumor development initiated by N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN). In the present study, we investigated variation in its promoting activity when the same total dose was given with different concentrations and exposure times. After 4 weeks administration of 0.05% BBN, group 1 served as a control without any post-initiation treatment. The rats in groups 2-4 received 1.25% Na-AsA diet for 36 weeks, 2.5% Na-AsA for 18 weeks and 5% Na-AsA for 8 weeks, respectively. Tumor number (papillomas and carcinomas) was greatest in group 3, and area in group 4 (P < 0.05). However, no enhancement was noted in group 2, although preneoplastic lesions were significantly increased. These results suggest that with the same total administration dose, high concentration of Na-AsA has the strongest promoting effects on tumor development in urinary bladder carcinogenesis.
Chen
T X
TX
Department of Pathology, Osaka City University Medical School, Osaka, Japan. fukuchan@med.osaka-cu.ac.jp
Wanibuchi
H
H
Wei
M
M
Morimura
K
K
Yamamoto
S
S
Hayashi
S
S
Fukushima
S
S
D000818:Animals; D001205:Ascorbic Acid / Q000633:toxicity*; D001973:Bromodeoxyuridine / Q000378:metabolism; D002085:Butylhydroxybutylnitrosamine / Q000633:toxicity; D002273:Carcinogens / Q000633:toxicity*; D004305:Dose-Response Relationship, Drug; D008297:Male; D051381:Rats; D011916:Rats, Inbred F344; D001749:Urinary Bladder Neoplasms / Q000139:chemically induced*
D002273:Carcinogens; D002085:Butylhydroxybutylnitrosamine; D001973:Bromodeoxyuridine; D001205:Ascorbic Acid