Epinephrine upregulates calpain activity in cultured C2C12 muscle cells

C2C12 cells were grown to confluence at 37 degrees C under a continuous 5% CO2 stream and myotube formation was stimulated. The cultures were then inc ubated with or without 2 mu g/mL epinephrine for 18 h prior to harvesting a nd calpain extraction. Epinephrine treatment resulted in a three-fold incre ase in extractable mu-calpain activity (P < 0.05), a three-fold increase in extractable m-calpain activity (P < 0.05), a 36% increase in calpastatin a ctivity (P < 0.001), and a 16% decrease (P < 0.05) in the total protein con tent in the C2C12 cell homogenate. These results suggest that calpains may play a role in protein metabolism and that the hormone epinephrine may be d irectly involved in the regulation of their cellular expression. (C) 2000 S ociete francaise de biochimie et biologie moleculaire / Editions scientifiq ues et medicales Elsevier SAS.