Re. Sotomayor et Mc. Washington, FORMATION OF ETHENO AND OXOETHYL ADDUCTS IN LIVER DNA FROM RATS EXPOSED SUBCHRONICALLY TO URETHANE IN DRINKING-WATER AND ETHANOL, Cancer letters, 100(1-2), 1996, pp. 155-161
Exposure of Fisher-344 male rats to 10 000 ppm of urethane in drinking
water for up to 90 days or in 5% ethanol for up to 14 days caused the
formation of 7-[2'-oxoethyl]guanine (OEG) and 1,N-6-ethenoadenine (ep
silon A) in liver DNA. Mild-acid DNA hydrolysates were analyzed by hig
h-performance liquid chromatography with photodiode array detection an
d fluorometry. The identification of OEG and epsilon A was confirmed b
y coelution with the authentic standards. Forty and 67% of rats showed
OEG and epsilon A adducts at 2 and 90 days of treatment with urethane
in drinking water, respectively. In comparison, only 0 and 10% of rat
s showed adducts at 2 and 14 days of treatment with urethane in 5% eth
anol, respectively, Neither OEG nor epsilon A was observed in control
rats receiving water or 5% ethanol. Although these data are still prel
iminary, they appear to suggest that ethanol may inhibit formation of
DNA adducts by urethane. Studies designed to produce more conclusive i
nformation about the role of ethanol in modifying DNA damage induced b
y urethane in vivo are in progress.