Fig. 4
From: Redox proteins are constitutively secreted by skeletal muscle
Effect of protease inhibitor on the abundance of secreted thioredoxin-1 (TRX-1) in the culture medium. a Immunoblotting of TRX-1 present in the myotube culture medium produced in the presence or absence of the protease inhibitor cocktail. C2C12 myotubes were stimulated by electric pulses of 50 V at 1 Hz for 3 ms for 1 h. Values in the vertical axis are in arbitrary units (AU). The amount of secreted TRX-1 present in the myotube culture medium was higher in the presence of protease inhibitor, but the secretion was not regulated by the contraction (n = 9–11). Two-way analysis showed a significant effect for the inhibitor. The amount of TRX-1 in the culture medium treated with protease inhibitor was significantly higher than that in the absence of the protease inhibitor [two-way ANOVA, F(1, 29) = 6.715, P < 0.05]. b LDH activity in C2C12 myotubes treated with protease inhibitor. Treatment with protease inhibitor or that combined with electrical stimulation did not result in an increase in the LDH activity in the medium (n = 9–11)