Electrical stimulation induced Hsp70 response in C2C12 cells

Electrical stimulation (ES) is widely used in experimental and clinical settings and shows effects on cellular response to stress; however; mechanisms underlying ES-induced effects are not thoroughly understood. We investigated the Hsp70 response in mouse myoblast derived C2C12 cells to ES at 13V in different groups (A: 12 Hz, 11 min; B: 12 Hz, 90 min; C: 100 Hz, 11 min) and harvested before ES and at 0h, Jh, 4h, 8h and 12h after ES, respectively. Control cells without ES were parallel treated to each stimulated group. Hsp70 expression was determined at protein level by quantitative Western-blot and at mRNA level by real-time PCR, respectively. ES in group A caused a modest biphasic Hsp70 response at mRNA level with a slight increase at protein level. In group B Hsp70 increased significantly (P < 0.01) at mRNA (559%) and protein level (413%), and remained elevated 12 h after ES. In group C the highest Hsp70 mRNA level (14-fold increase, P < 0.01) was observed at 4h after ES with only a moderate increase at protein level (147%, P < 0.05) at 8h after ES. Thus, ES induced distinct Hsp70 responses at both protein and mRNA level, and the characteristics of ES determined the pattern and time course of Hsp70 response in the cultured cells. ES induced Hsp70 response may serve as a common mechanism underlying diverse effects of ES and plays an important role in cellular adaptive response to ES.