Fig. 6

Relationship between passive force and SL-dependent Ca²⁺ activation (ΔpCa₅₀) in the absence (Control) and presence of MgADP or Pi obtained in the short (2.0−2.4 μm: closed symbols) and long (2.4−2.8 μm: open symbols) SL ranges. Control, Y = 0.0965 + 0.0166X (R = 0.88; P < 0.0005); MgADP, Y = 0.0317 + 0.0175X (R = 0.81; P < 0.005); Pi, Y = 0.132 + 0.0367X (R = 0.78; P < 0.005). The difference in slope was significant between the control and Pi groups (but not between the control and MgADP groups). ΔPassive force denotes the difference between the values of passive force at SL 2.0 and 2.4 μm (or at SL 2.4 and 2.8 μm)