Table 1.

Cell contractility and Ca²⁺ transients in cardiomyocytes from WT and RARαKO Mice

	WT (n=6)	RARαKO (n=7)	RARαKO+NAC (n=4)
Cell Contractility
Peak shortening (%)	5.49±0.31	3.37±0.25*	3.81±0.16
+dL/dt (μm/s)	162.3±17.7	86.5±9.56*	134.8±10.6†
−dL/dt (μm/s)	104.8±12.2	43.2±7.4*	89.3±13.1†
TPS50% (s)	0.058±0.002	0.061±0.002	0.059±0.003
TPS90% (s)	0.096±0.006	0.106±0.006	0.098±0.006
TR50% (s)	0.236±0.016	0.293±0.018*	0.2446±0.026†
TR90% (s)	0.411±0.028	0.669±0.052*	0.462±0.033†
Tau (s)	0.135±0.009	0.196±0.013*	0.144±0.023†
Ca2+ transients
Baseline	1.121±0.019	1.145±0.012	1.148±0.017
dep v	2.354±0.174	2.422±0.142	2.387±0.502
dep v t	0.024±0.002	0.019±0.012	0.021±0.002
bl%peak h	6.538±0.445	6.569±0.477	6.333±1.095
T50CI (s)	0.029±0.002	0.026±0.001	0.027±0.001
T90CI (s)	0.052±0.002	0.048±0.001	0.049±0.001
SR load	0.502±0.041	0.449±0.036	0.476±0.042
ret v	0.658±0.060	0.397±0.017*	0.551±0.028†
T50CR(s)	0.249±0.008	0.305±0.007*	0.274±0.007†
T90CR (s)	0.546±0.034	0.805±0.052*	0.627±0.016†
Tau (s)	0.242±0.009	0.358±0.014*	0.291±0.024†

Adult cardiomyocytes isolated from WT and RARαKO mice after 20 wks of gene deletion, treated with or without NAC for 30 min. Cells were field stimulated, mechanical properties and intracellular Ca²⁺ transients were measured. NAC: N-acetyl-L-cysteine. For cell contractility: TPS50% and TPS90%: time to 50% and 90% of the peak shortening; TR50% and TR90%: time to 50% or 90% cell relengthening; Tau: the exponential decay time constant of the function. For Ca²⁺ transients: dep v: maximum velocities of Ca²⁺ transient ratio increase; T₅₀CI and T₉₀CI: time to 50% or 90% of Ca²⁺ transient ratio increase; ret v: maximum velocities of Ca²⁺ transient ratio recovery; T50CR and T90CR: time to 50% or 90% of Ca²⁺ transient ratio recovery; Tau: single exponential intracellular Ca²⁺ decay. Data are means ± SEM.

^*P<0.05 vs WT;

^†P<0.05 vs RARαKO.