Fig. 2.

Tamoxifen augments the strength of leg muscles of XLMTM mice. Electrically evoked triceps contractions were recorded under isometric conditions and contractile features analyzed in 42, 84, and 210-day-old mice fed placebo or tamoxifen-supplemented (30 mg kg⁻¹) diets. a Average traces showing absolute phasic (twitch) contraction of the triceps at 42 days (D42). Tamoxifen significantly enhanced the force (tension) in Mtm1^−/y mice. b Specific phasic force (see Online Methods for details) of D42 Mtm1^−/y mice augmented with tamoxifen. c Specific phasic force of Mtm1^−/y mice increased with tamoxifen at all examined ages. d Average traces showing triceps absolute force-frequency curves at D42. Tamoxifen more than doubled the tetanic force of Mtm1^−/y mice. e Specific force of Mtm1^−/y mice markedly augmented with tamoxifen at all stimulation frequencies. f Specific tetanic force of Mtm1^−/y mice was considerably improved at all studied ages. In triceps examined after various treatment durations, tamoxifen rescued the impaired time to twitch peak of Mtm1^−/y mice (g) but had no impact on the time required for half-relaxation from peak (h). D42 panels: WT wild type; legend in a stands for a, b, d, e; data represent the mean ± s.e.m. of n = 7 triceps per group. c, f, g, h: black triangles illustrate increasing age (42–84 and 210 days) within each treatment group; columns from left to right: data represent the mean ± s.e.m. of 7; 8; 7; 7; 7; 13; 7; 0; 0; 7; 8; 6 triceps, respectively. *P ≤ 0.05; **P ≤ 0.01; ***P ≤ 0.001; ****P ≤ 0.0001; ns non-significant, Ø no surviving mice. One-way ANOVA followed by Fisher’s LSD post-test