Table 3.

Effect of the D73N mutation on Ca²⁺ transients and sarcomere length shortening measurements.

Parameter	WT	WT /+ ISO	D73N /(+/−)	D73N /(+/−)+ISO
Ca2+ TRANSIENT MEASUREMENTS
Baseline (R)	0.76±0.03	0.75±0.02	0.71±0.02	0.72±0.01
Peak height (R)	0.51±0.04	0.71±0.04†	0.48±0.03	0.52±0.03‡
Time to 50% peak (s)	0.016±0.001	0.0123±0.0004†	0.020±0.002*	0.018±0.001‡
Time to 75% peak (s)	0.021±0.001	0.0163±0.0005†	0.026±0.002*	0.023±0.001‡
Time to 50% baseline(s)	0.175±0.008	0.142±0.006†	0.177±0.008	0.164±0.006‡
Time to 75% baseline (s)	0.29±0.01	0.20±0.01†	0.24±0.01*	0.22±0.01≠
Departure velocity (R/s)	31±3	51±4†	28±3	27±2‡
Return velocity (R/s)	−2.7±0.3	−5.6±0.4†	−3.4±0.3	−4.0±0.4‡≠
SARCOMERE LENGTH SHORTENING MEASUREMENTS
Resting SL length (μm)	1.64±0.02	1.64±0.02	1.70±0.01*	1.69±0.02≠
Peak height (μm)	0.100±0.009	0.20±0.01†	0.117±0.009	0.12±0.01‡
Fractional shortening (%)	6.1±0.5	12.3±0.8†	6.9±0.5	7.4±0.7‡
Time to 50% peak (s)	0.046±0.004	0.038±0.003	0.065±0.003*	0.059±0.003‡≠
Time to 75% peak (s)	0.071±0.006	0.055±0.005	0.088±0.004*	0.082±0.004‡
Time to 50% baseline (s)	0.27±0.03	0.22±0.02	0.29±0.01	0.27±0.01
Time to 75% baseline (s)	0.31±0.03	0.25±0.03	0.33±0.02	0.33±0.02‡
Departure velocity (μm/s)	−2.2±0.3	−4.8±0.5†	−1.8±0.2	−2.0±0.2‡
Return velocity (μm/s)	1.1±0.2	3.0±0.5†	1.0±0.1	1.2±0.3‡

Ventricular myocytes were isolated from 8 ± 0.7 week old mice. Data values are expressed as mean ± S.E. (n = 14–19 cells isolated from three hearts per genotype). SL, sarcomere length; R, ratio 340/380. Time to 50% peak, time to 75% peak, time to 50% baseline and time to 75% baseline were measured from time 0.

^*D73N (+/−) values significantly different from their respective WT values;

^†WT + ISO values significantly different from their respective WT values;

^‡D73N (+/−) + ISO values significantly different from their respective WT + ISO values;

^≠D73N (+/−) + ISO values significantly different from their respective WT values. The p-value < 0.05 was considered statistically significant.