The effect of paraquat on the incorporatipon of 14C-leucine and 14C-palmitate into lung proteins and lung lipids of rats and rabbits
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The results of this comparative study show that paraquat added in vitro inhibited lipid and protein biosynthesis by lung slices from rats and rabbits during the first 2 hours of incubation. This inhibition was maintained in spite of an increased oxygen uptake and pentose pathway activity during this period. Paraquat (1 mM) added in vitro caused significant inhibition of 14C-leucine and 14C-palmitate incorporation into the soluble proteins and total lipids respectively of rat and rabbit lung slices. The effect of paraquat (27 mg/kg) administered intraperitoneally to rats and rabbits and assessed on the rate of 14C-leucine incorporation in vitro 24 hours after injection, also showed a significant inhibition. However, after 48 hours, protein synthesis was stimulated in rat lungs, whereas paraquat had no effect on rabbit lungs. A highly significant suppression of the rate of14C-palmitate incorporation 24 hours after intraperitoneal injection of paraquat was found with rat lung slices, whereas with rabbit lung slices the degree of inhibition was not significant. Forty-eight hours after injection a highly significant inhibition was maintained in rat lung slices while rabbit lung slices showed no inhibition. This finding points to a species difference in the effect of paraquat on metabolic processes and may explain the resistance of rabbit lung to damage by paraquat.
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