Fig. 4. Dependence of n_H and pCa₅₀ on F₀.

a n_H−F₀ relations for the soleus fibres in control (circles) and in the presence of 1 μM OM (triangles). Filled symbols, pooled data from twenty-three fibres; open symbols, mean values (±SEM) at each temperature. Different colours refer to different temperatures: 12 °C, blue; 17 °C, green; 25 °C, orange; 35 °C, brown. Lines are first order regression equations fitted to pooled data (continuous, control; dashed, OM). The slope and the ordinate intercept of the regressions are: control, 1.10 ± 0.15 pN^-1 and 0.19 ± 0.32 respectively; 1 μM OM, 0.25 ± 0.13 pN^-1 and 0.65 ± 0.18 respectively. b pCa₅₀−F₀ relations in the soleus fibre in control (circles) and in the presence of 1 μM OM (triangles) from the same force-pCa relations as in a. Lines are the first order regression equations fitted to pooled data (continuous, control; dashed, OM). The slope and the ordinate intercept of the regressions are: control, 0.28 ± 0.07 pN^-1 and 5.92 ± 0.14 respectively; 1 μM OM, −0.06 ± 0.11 pN^-1 and 7.26 ± 0.15 respectively. c Superimposed n_H–F₀ relations in control from the soleus fibres (circles from a) and from psoas fibres (reverse triangles, pooled from ref. ³³ and new data for a total of twelve fibres). Different colours of reverse triangles refer to different temperatures: 6 °C, magenta; 12 °C, blue; 25 °C, orange. The continuous line is calculated from the linear fit of the relation of reciprocal of pooled n_H−F₀ data (continuous line in d), the horizontal dashed line is drawn starting from the ordinate that is the reciprocal of the ordinate intercept in d. d Same data as in c plotted as reciprocals. The line is the first order regression equation fitted to the pooled data (slope, 0.61 ± 0.05 pN; ordinate intercept, 0.12 ± 0.02; abscissa intercept -0.20 ± 0.04 pN^-1).