Fig. 5.

[Ca²⁺]_c transients, [Ca²⁺]_c decay kinetics, and SR Ca²⁺ pumping rate during contractions when mitochondrial respiration was blocked with NaCN. A: basal and peak [Ca²⁺]_c responses in the presence of BTS (○) and in the presence of BTS + NaCN (△). †P < 0.05 BTS + NaCN vs. BTS, two-way repeated-measures ANOVA. B: fast-phase rate of [Ca²⁺]_c decay (λ₁) in the presence of BTS (○) or BTS + NaCN (△). *P < 0.05 vs. initial contraction, one-way repeated-measures ANOVA. C: mean data of [Ca²⁺]_c dependence of the rate of [Ca²⁺]_c decline at different time points of the contractile bout in the presence of BTS (closed symbols) or BTS + NaCN (open symbols). n = 4 fibers. Values are expressed as means ± SE. Time points selected were the same as in Fig. 4 (indicated as a, b, and d). Rate of SR Ca²⁺ pumping was determined as described in methods and in Fig. 4. The curves from the mean data were fitted with Eq. 4, but N and L were not fixed.