Table 1. Characteristics of Ca²⁺ sparks.

Ca²⁺ activities were measured at 50 nM of [Ca²⁺]_i in permeabilized CMs from WT and PLB-KO as indicated in Fig. 5. Ca²⁺ sparks were measured at baseline, after IP₃, after anti-PLB Fab and 2-APB and analyzed using the SparkMaster plug-in for ImageJ software [55]. Parameters of Ca²⁺ sparks characteristics were compared 6 using one-way ANOVA with Tukey post-tests. Results are the means ± SEM from 12 CMs from 6 WT and 13 7 CMs from 6 PLB KO mice. * indicates P<0.05 vs baseline, ^† vs. IP3, ^‡ vs. Fab. FWHM: full width at half 8 maximum; FDHM: full duration half maximum; DT₅₀: half decay time.

WT Nu	Spark numbers (/100 μm.s)	Peak amplitude F/F0	FWHM, μm	FDHM, ms	DT50, ms
control	2.6 ± 0.5	1.8 ± 0.1	1.7 ± 0.2	30.4 ± 3.9	36.5 ± 6.0
IP3	8.3 ± 0.9 *	1.8 ± 0.1	1.9 ± 0.1	35.0 ± 3.6	52.6 ± 11.6
Fab	8.8 ± 0.8 *	2.2 ± 0.1 *†	2.8 ± 0.2 *†	69.1 ± 6.6 *†	118.6 ± 29.9 *†
2-APB	2.3 ± 0.4 † ‡	1.8 ± 0.1 ‡	1.7 ± 0.2 ‡	28.0 ± 4.4 ‡	29.7 ± 3.2 ‡
WT Cy
control	4.3 ± 0.4	3.1 ± 0.1	2.9 ± 0.1	28.9 ± 1.4	24.2 ± 1.4
IP3	6.4 ± 0.8	3.3 ± 0.1	3.0 ± 0.1	27.9 ± 0.8	28.2 ± 1.7
Fab	8.3 ± 0.5 *	4.2 ± 0.1 *†	3.8 ± 0.1 *†	40.2 ± 1.9 *†	37.2 ± 1.9 *†
2-APB	3.9 ± 0.6 † ‡	2.9 ± 0.1 ‡	2.8 ± 0.1 ‡	26.1 ± 1.0 ‡	29.9 ± 1.9 ‡
KO Nu
control	5.6 ± 0.4	1.9 ± 0.1	1.7 ± 0.2	32.0 ± 3.8	38.5 ± 5.7
IP3	8.6 ± 0.4 *	2.3 ± 0.1 *	2.8 ± 0.2 *	67.5 ± 4.2 *	107.8 ± 7.6 *
Fab	8.4 ± 0.3 *	2.3 ± 0.1 *	2.8 ± 0.2 *	65.3 ± 4.0 *	103.6 ± 7.3 *
2-APB	4.2 ± 0.3 † ‡	1.9 ± 0.1 † ‡	1.9 ± 0.2 † ‡	40.9 ± 5.7 † ‡	58.8 ± 14.3 † ‡
KO Cy
control	7.5 ± 0.6	3.3 ± 0.1	2.9 ± 0.1	28.6 ± 1.0	27.0 ± 1.2
IP3	9.7 ± 0.7	3.8 ± 0.1 *	3.1 ± 0.1	32.4 ± 1.7	30.7 ± 2.0
Fab	9.5 ± 0.6	3.8 ± 0.1 *	3.1 ± 0.1	31.8 ± 1.5	31.0 ± 2.2
2-APB	5.4 ± 0.5 † ‡	3.3 ± 0.1 † ‡	2.7 ± 0.1	27.5 ± 1.3	29.6 ± 1.6