Transplacental effects of carcinogens and non-carcinogens on activities of pyruvate kinase and lactate dehydrogenase as well as isozymic pattern of LDH in mouse lung.

The carcinogens, urethane (URTH), 3-methylcholanthrene (MCA) and dimethylnitrosamine (DMN) given to pregnant mice enhanced permanently the activities of pyruvate kinase (PK) and lactate dehydrogenase (LDH) in the lungs of offspring even well before the appearance of lung tumours. The noncarcinogenic analogues phenylurethane (PHUR) and pyrene (PYR), had no effect on PK or LDH activity. The non-carcinogenic pulmonary toxicant Paraquat (PAR) elicited only a temporary elevation in the activities of the enzymes tested. The H:M ratio of LDH sub-units in the lung tissue was permanently decreased by URTH administered transplacentally. PAR caused only a temporary decrease in the H:M ratio, while PHUR had no effect on the isozymic pattern of LDH.