Table 2.

Average values of Hill fit to Ca²⁺-force curves for CM, FSM and SSM muscle fibres at sarcomere lengths of 1.95, 2.10 and 2.25 μm

	CM (n = 7)			FSM (n = 8)			SSM (n = 8)
	1.95	2.10	2.25	1.95	2.10	2.25	1.95	2.10	2.25
EC50 (μM)	3.40 ± 0.15	3.10 ± 0.16	2.75 ± 0.16	2.45 ± 0.12*	2.24 ± 0.11*	2.03 ± 0.10*	2.36 ± 0.13*	2.22 ± 0.14*	2.11 ± 0.15*
pCa50 (μM)	5.47 ± 0.02	5.51 ± 0.02	5.56 ± 0.03	5.61 ± 0.02*	5.65 ± 0.02*	5.70 ± 0.02*	5.63 ± 0.03*	5.66 ± 0.03*	5.68 ± 0.03*
Hill coeff.	6.50 ± 0.29	6.01 ± 0.59	5.40 ± 0.31	5.63 ± 0.76	5.82 ± 0.30	5.61 ± 0.57	2.57 ± 0.17*	2.39 ± 0.19*	2.34 ± 0.21*
				CM	FSM	SSM
			ΔEC50	0.65 ± 0.04	0.42 ± 0.05*	0.25 ± 0.04*†
			ΔpCa50	0.09 ± 0.01	0.08 ± 0.01	0.05 ± 0.01*†

Each column indicates the averaged EC₅₀, pCa₅₀, and Hill coefficient values of the Ca²⁺-force curves obtained from rat cardiac trabeculae (CM), rat psoas (FSM), and soleus (SSM) muscle fibers at the SLs listed. The lower part of the table indicates the average length-dependent changes in Ca²⁺-sensitivity (ΔEC₅₀ or ΔpCa₅₀) for the three muscle types calculated as the difference in EC₅₀ and pCa₅₀ between SL = 2.25 μm and 1.95 μm

^*P < 0.01 vs.CM

^†P < 0.01 vs.FSM).