||Effect of Single Versus Split Doses of Diethyinitrosamine on the Induction of Gamma-Glutamyltranspeptidase-Foci in the Livers of Adult and Juvenile Rats.
Herren-Freund, S. L. ;
Pereira, M. A. ;
Long, R. E. ;
Khoury, M. M. ;
||Environmental Protection Agency, Cincinnati, OH. ;Pathology Associates, Inc., Cincinnati, OH.
Laboratory animals ;
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The induction of gamma-glutamyltranspeptidase (GGT)-foci by single and by split doses of diethylnitrosamine (DENA) was evaluated in the livers of juvenile and young adult male, Sprague-Dawley rats. A single dose of DENA was administered at either 32, 41 or 52 days of age and followed by a promoting regimen of sodium phenobarbital in the drinking water. In 32 day old rats, DENA resulted in a higher incidence of GGTfoci/cu.cm. than were observed when it was administered to 41 or 46 day old rats. The same dose of DENA was inactive in 52 or 60 day old rats. In rats initiated with DENA on day 32 of age, starting the phenobarbital promotion at 41 days of age resulted in a higher incidence of GGT-foci than when the phenobarbital treatment was begun at 60 days of age. When the dose of DENA was split into 5 daily doses of DENA starting on day 32 of age, the incidence of GGT-foci/cu.cm. was equivalent to the single dose given on day 32 of age.