The effect of paraquat on the incorporation of radiolabelled proline into acid-extractable lung proteins and collagens

: In this comparative study we describe the influence of paraquat on the rate of L-2,3-3H-proline incorporation 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/microgram hydroxyproline.