title: Effects of insulin and IGF-I on RNA synthesis in isolated soleus muscle.
abstract: The effects of insulin and insulin-like growth factor I (IGF-I) on RNA synthesis and the effect of IGF-I on polypeptide chain initiation have been studied in the isolated mouse soleus muscle. Both peptides after a 3 h incubation enhanced net incorporation of the labelled uridine into RNA to a similar extent (40% increase over basal). The maximally effective concentrations were 66 nM and 100 nM for insulin and IGF-I respectively. Actinomycin D prevented the peptides' effect on RNA synthesis without modifying their effect on protein synthesis. Furthermore IGF-I increased the rate of initiation of polypeptide chains. It is suggested that in muscle, IGF-I and insulin stimulate protein synthesis by a dual mechanism: a rapid effect on the rate of polypeptide chain initiation; a slower effect on RNA synthesis.
mesh_terms: D000818:Animals; D003609:Dactinomycin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D007328:Insulin / Q000494:pharmacology*; D007700:Kinetics; D051379:Mice; D009132:Muscles / Q000187:drug effects / Q000378:metabolism*; D010442:Peptide Chain Initiation, Translational / Q000187:drug effects; D010455:Peptides / Q000494:pharmacology*; D012313:RNA / Q000096:biosynthesis*; D013002:Somatomedins / Q000494:pharmacology*; D014529:Uridine / Q000378:metabolism
chemical_list: D007328:Insulin; D010455:Peptides; D013002:Somatomedins; D003609:Dactinomycin; D012313:RNA; D014529:Uridine