The effects of benzo(a)pyrene on rat liver lysosomes.

An i.p. injection of benzo(a)pyrene (BP; 10 mg/kg) into rats led to the progressive release of hepatic, beta-glucuronidase (beta-Gluc), beta-galactosidase (beta-Gal) and beta-N-acetylglucosaminidase (beta-Glm). This occurred prior to the appearance of altered cells or cell populations from which malignant transformations may gradually develop. The in vitro studies on the latency of beta-Gluc, Beta-Gal and beta-Glm in the lysosome-enriched rat liver suspension treated with BP showed that concentrations of 10(-7) M, 10(-6) M and 10(-5) M significantly decrease latency of all three lysosomal enzymes, the effect being time-dependent. These concentrations of BP did not alter the activities of beta-Gluc, b-Gal and beta-Glm in vitro. No significant alterations were observed in total enzyme activities, following in vivo and in vitro BP administration. BP exerts its effect on rat liver lysosomes by modifying the structural properties of the lysolemma, and may represent an early precarcinogenic change.