Fig. 3.
Normalized pCa-tension relationships and SL dependency of myofilament Ca2+ sensitivity. Isometric steady-state tension values were normalized to the maximal tension generated in pCa 4.3 solution. The Hill equation was fitted to the normalized data to estimate pCa50 and nH. A: pCa-tension relationships at SL 1.9 μm. B: pCa-tension relationships at SL 2.2 μm. C: SL dependency of myofilament Ca2+ sensitivity. Two-way ANOVA showed that the ELC-SL interaction effect on pCa50 was significant (P < 0.05). Subsequent post hoc Holm-Bonferroni tests revealed that the increase in pCa50 caused by ELC-Δ43 was significant (*P < 0.05) only at SL 1.9 μm, indicating that SL dependency of myofilament Ca2+ sensitivity was ablated in Tg-Δ43 fibers. White circles represent Tg-WT, and black circles represent Tg-Δ43 fibers. Values are denoted as means ± SE. At least 7 fibers were used for each group.