Browsing by Author "Nienaber, M. W. P."
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- ItemThe effect of paraquat on the incorporation of radiolabelled proline into acid-extractable lung proteins and collagens(Health & Medical Publishing Group, 1982) Engelbrecht, F. M.; Windt, M.-L.; Maree, E.; Nienaber, M. W. P.In this comparative study the authors describe the influence of paraquat on the rate of L-2,3-3H proline incorportion into the acid-extractable proteins and into newly synthesized protropocollagen molecules from the lungs of rats and rabbits. Exposure to paraquat took two forms: (a) addition of paraquat in vitro to lung tissue taken from rats and rabbits, and (b) intraperitoneal injection of paraquat prior to death. Paraquat (0,5-1,0 mM) added in vitro significantly slowed the rates of 3H-proline incorporation into the acid-extractable proteins and into newly synthesized protropocollagen in both rat and rabbit lung tissue. Paraquat administered intraperitoneally (27 mg/kg) to rabbits did not markedly influence the rate of 3H-proline incorporation into acid-extractable proteins and collagen assessed in vitro 24, 48 and 96 hours after injection. Paraquat injected intraperitoneally into rats induced no significant difference in synthesis rates of acid-soluble proteins up to 48 hours after injection. During the same period, the collagen synthesis rate of rat lung tissue was reduced. At 96 hours an increase was found when the rate of synthesis was expressed as cpm/mg DNA and as cpm/μg hydroxyproline.
- ItemThe effect of paraquat on the incorporatipon of 14C-leucine and 14C-palmitate into lung proteins and lung lipids of rats and rabbits(Health & Medical Publishing Group, 1981) Engelbrecht, F. M.; Rossouw, D. J.; Nienaber, M. W. P.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.