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. 2002 May 15;541(Pt 1):187–199. doi: 10.1113/jphysiol.2001.013418

Figure 4. Influence of BDM on the inhibition of isometric force by Pi in maximally activated psoas and soleus myofibrils.

Figure 4

A, experimental tracing from a multiple-jump protocol (1 mm Pi, 2 mm BDM) on a psoas myofibril (5 °C). 1 mm Pi-jump: relative force = 0.75 of maximal Pi-free value; 1 mm Pi + 2 mm BDM jump: relative force = 0.49. kTR of force development or redevelopment in control conditions: 1.9 s−1 and 2.3 s−1, respectively. B, experimental tracing from a multiple-jump protocol (50 mm Pi, 10 mm BDM) on a soleus myofibril (15 °C). 50 mm Pi-jump: relative force = 0.51; 50 mm Pi + 10 mm BDM: relative force = 0.38. kTR of force development in control conditions: 1.5 s−1. C, force-[Pi] curve obtained in psoas myofibrils at 5 °C in the presence of 2 mm BDM. Continuous line: hyperbolic fitting of experimental points (Kd,app = 0.77 ± 0.07 mm; Asymptoteapp = 0.08 ± 0.07). Dashed line: hyperbolic fit of the force-[Pi] relation (no BDM) at the same temperature from Fig. 2A. Dotted line: mean effect of 2 mm BDM alone at the same temperature (relative force: 0.74 ± 0.02, n = 5). D, force-[Pi] curve obtained in soleus myofibrils at 15 °C in the presence of 10 mm BDM. Continuous line: hyperbolic fit of experimental points (Kd,app = 1.27 ± 0.01 mm; Asymptoteapp = 0.32 ± 0.01). Dashed line: hyperbolic fit of the force-[Pi] relation (no BDM) at the same temperature from Fig. 2B. Dotted line: mean effect of 10 mm BDM alone at the same temperature (0.74 ± 0.05, n = 11).