Fig. 8

Effects of NKCC1 inhibition on muscle force generation and ERK phosphorylation. A Isometric tetanic force generation of EDL muscles is not altered by bumetanide (BUM) incubation, as compared with vehicle (VEH) control. Raw values showing forces in Ringer’s solution as pre-treatment (Pre-Tx), and the forces following 20–30-min incubation in 50 μM bumetanide or vehicle (ethanol) as post-treatment (Post-Tx). B Decrement of force following eccentric contractions (ECC) is not affected by bumetanide incubation. Forces are relative to the initial force in the first ECC. Means shown; error bars SEM. C levels of phosphorylated ERK are elevated in resting EDL muscles from wild-type mice, but the P-ERK response to ECC is unaffected. (*, P < 0.05, paired t-test between bumetanide and vehicle incubation for muscles from the same mouse). D Bumetanide incubation inhibits ECC-induced increases in P/T-ERK in the absence of Sgcg. N = 3–6 muscles per condition. *Significant difference between vehicle and bumetanide within strain (P = 0.0196), by 2-way ANOVA followed by Sidak’s multiple comparisons test. C, D Central lines, means; error bars, SEM. E Representative immunoblots. The signals from phosphorylated (P) to total (T) ERK signal were determined for each condition, and then the ratio of the P/T ERK signals after ECC were divided by the corresponding ratio at rest for each condition (ECC/Rest)