Dexamethasone-induced catabolism and insulin resistance in L6 myoblasts are reversed by the removal of serum.
1. One hundred nanomolar dexamethasone reduced protein synthesis by 16% and also decreased the accretion of protein and RNA in L6 myoblasts when foetal calf serum was present; these effects were reversed when serum was omitted from the medium. 2. Insulin (100 microU/ml) increased protein synthesis, protein accretion and RNA accretion both in the presence and the absence of serum. 3. Dexamethasone inhibited the effects of 100 microU insulin/ml in the presence of serum and induced insulin resistance; in the presence of 25 or 100 nM dexamethasone insulin was ineffective at concentrations below 250 microU and 1 mU/ml respectively.
Palmer
R M
RM
Rowett Research Institute, Bucksburn, Aberdeen, Scotland.
Bain
P A
PA
Southorn
B G
BG
D000818:Animals; D001769:Blood; D002460:Cell Line; D003907:Dexamethasone / Q000494:pharmacology*; D004347:Drug Interactions; D007328:Insulin / Q000494:pharmacology; D007333:Insulin Resistance; D009132:Muscles / Q000187:drug effects / Q000378:metabolism*; D014176:Protein Biosynthesis; D011506:Proteins / Q000378:metabolism*; D012313:RNA / Q000378:metabolism
D007328:Insulin; D011506:Proteins; D012313:RNA; D003907:Dexamethasone