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Comparative effects of cadmium, zinc, and lead in vitro on pulmonary, adrenal, and hepatic microsomal metabolism in the guinea pig.
Colby HD; Johnson PB; Zulkoski JS; Pope MR; Miles PR
J Toxicol Environ Health 1981 Jan; 8(5-6):907-915
The effects of cadmium (7440439) (Cd), zinc (7440666) (Zn) and lead (7439921) (Pb) on microsomal metabolism were investigated in the guinea-pig. Adrenals, lungs, and livers were obtained from English- short-haired-guinea-pigs after sacrifice. Tissues were homogenized and microsomes were obtained by differential centrifugation. The microsomal preparation was assayed for enzymatic activity in the presence and absence of from 20 to 200 micromoles of Cd, Zn, or Pb. Cd and Zn caused concentration dependent decreases in benzphetamine- demethylase and biphenyl-hydroxylase activities in liver, lung, and adrenals. Pb had no effect on either of these enzymes. Benzo(a)pyrene-hydroxylase and ethoxycoumarin-deethylase activities were also inhibited by Zn, Cd, and Pb in adrenal, liver and lung microsomes. Zn inhibited steroid 21-hydroxylase activity in adrenal microsomes. Microsomal epoxide-hydratase activity in adrenal, liver, and lung was inhibited by Cd. Inhibition of mixed function oxidases by metals was not related to changes in cytochrome P-450 concentrations. The authors conclude that those metals inhibit adrenal, pulmonary, and liver microsomal enzymes and the actions of the metals are highly dependent on the substrates used.
NIOSH-Author; Heavy-metals; Laboratory-animals; Enzyme-activity; Invitro-study; Hepatic-microsomal-enzymes; Comparative-toxicology; Metabolism
7440-43-9; 7440-66-6; 7439-92-1
Issue of Publication
Journal of Toxicology and Environmental Health
Page last reviewed: November 6, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division