RELATIONSHIP BETWEEN A LONG-TERM TREATMENT OF 2-MERCAPTOETHANOL AND PROTEIN-METABOLISM IN THE AGING RAT

Female RLEF1/Lati rats were chronically treated with 2-mercaptoethanol in a dose of 13-mu-g.100 g bw-1.day-1 dissolved in drinking water. During a 48-h experiment N-15-labelled glycine was given orally in a dose of 5 mg N-15.kg bw-1 and urine samples were collected and analysed by an emission spectrometric isotope method. Protein synthesis and nitrogen excretion rate constants were calculated according to the three-pool model, and 3-methylhistidine excretion rates were also determined. 2-Mercaptoethanol appears to influence protein metabolism; however, the slower rates of protein synthesis proved to be apparent in almost all groups of treated rats. Protein synthesis and nitrogen excretion rate constants have exceptionally high values in 2-year-old rats, possibly explained by the occurrence of hypercompensation mechanisms in old age. These were reflected by the excretion rates of 3-methylhistidine which were reduced as a result of sulphhydryl group interactions in age-dependent cellular metabolic changes.