[RNA metabolism and ageing (author's transl)].

The labelling behaviour of RNA fractions in rat liver after application of 32P-orthophosphate and 14C-orotate in vivo in young (3-5 months) and old animals (20 months) was presented. Whereas the tracer incorporation in old animals 60 minutes after 32P-application seems to be decreased we observed increased specific activities of nuclear RNA 30 and 60 minutes after application of 14C-orotate i.p. - Measuring of RNA synthesis in isolated cell nuclei after in vivo stimulation by cortisol (2 mg/100 g body weight) showed a stronger and longer continued stimulation in young animals as in old both in the Mn++ system and in the Mg++ system. When we compared the young with the old controls the rate of synthesis was increased in the old controls. The results support observations on changed regulations of the transcription of genetic informations in the age.