Epinephrine upregulates calpain activity in cultured C2C12 muscle cells

Abstract

C2C12 cells were grown to confluence at 37 °C under a continuous 5% CO 2 stream and myotube formation was stimulated. The cultures were then incubated with or without 2 μg/mL epinephrine for 18 h prior to harvesting and calpain extraction. Epinephrine treatment resulted in a three-fold increase in extractable μ-calpain activity ( P < 0.05), a three-fold increase in extractable m-calpain activity ( P < 0.05), a 36% increase in calpastatin activity ( P < 0.001), and a 16% decrease ( P < 0.05) in the total protein content in the C2C12 cell homogenate. These results suggest that calpains may play a role in protein metabolism and that the hormone epinephrine may be directly involved in the regulation of their cellular expression.