Table 2. Force measurements in failing cardiomyocytes after exchange with recombinant cTn at sarcomere length 1.8 and 2.2 μm.

IDCM cardiomyocytes exchanged with Wt, 42D/44D and 42A/44A troponin complex (2 samples; 8 myocytes per complex). Myofilament force was measured at sarcomere lengths of 1.8 and 2.2 μm at different Ca²⁺-concentrations. Stretching of cardiomyocytes from 1.8 to 2.2 μm significantly increased Ca²⁺-sensitivity (pCa₅₀), maximal (F_max) and passive force (F_pas) in all groups. There was no significant effect of sarcomere length on nHill (steepness of the force-pCa curves). Two-way ANOVA repeated measures followed by a Bonferroni post-hoc test revealed a significant decrease in Ca²⁺-sensitivity in 42D/44D and 42A/44A compared to Wt at both sarcomere lengths (#P<0.05, significant difference compared to Wt). When two-way ANOVA revealed a significant effect for sarcomere length (P<0.05), paired t-tests were performed to compare cell measurements at two different sarcomere lengths in each cTn-exchange group (*P<0.05, 1.8 vs 2.2 μm). Wt data has been published before.²³ Values are means ± SEM.

		Wt	42D/44D	42A/44A
Fmax (kN.m−2)	1.8 μm	14.5±0.8	10.2±1.4	12.2±2.2
	2.2 μm	18.0±1.0*	13.7±1.6*	15.1±2.0*
Fpas (kN.m−2)	1.8 μm	2.2±0.1	2.4±0.3	1.9±0.3
	2.2 μm	3.3±0.3*	3.6±0.4*	3.1±0.5*
pCa50	1.8 μm	5.64±0.02	5.42±0.01#	5.56±0.02#
	2.2 μm	5.67±0.02*	5.45±0.01#,*	5.60±0.02#,*
nHill	1.8 μm	2.9±0.1	2.4±0.2	2.5±0.2
	2.2 μm	2.7±0.1	2.4±0.1	2.5±0.2