Table 1.

Steady-state mechanical properties of WT and KO ventricular multicellular preparations.

Group	Fmin (mN/mm2)	Fmax (mN/mm2)	nH	pCa50
SL 1.9 μm
WT	0.82 ± 0.12*	17.29 ± 1.98*	3.41 ± 0.32*	5.71 ± 0.02*
KO	0.90 ± 0.13*	14.93 ± 1.56*	2.30 ± 0.08†	5.80 ± 0.01*†
SL 2.1 μm
WT	2.14 ± 0.28	26.32 ± 2.93	2.47 ± 0.22	5.82 ± 0.02
KO	1.97 ± 0.25	23.98 ± 2.58	2.49 ± 0.23	5.87 ± 0.02

F_min: Ca²⁺-independent force measured at pCa 9.0; F_max: maximal Ca²⁺-activated force measured at pCa 4.5; n_H: Hill coefficient of the force-pCa relationship; pCa₅₀: pCa value required for the generation of half-maximal force. Values are expressed as mean ± s.e.m., from 7 to 17 multicellular preparations and 3 to 5 hearts per each group.

^*Significantly different from the corresponding group at SL 2.1 μm; P < 0.05.

^†Significantly different from the corresponding WT group at SL 1.9 μm, P < 0.05.