Parameters determined in voltage-clamp experiments
| Parameter | WT | R6/2 | Significance |
| L-type calcium current | |||
| Activation | |||
| V1/2 (mV) | 0.40 ± 0.56 | −6.20 ± 1.14 | *** |
| k (mV) | 5.05 ± 0.18 | 6.68 ± 0.46 | *** |
| gmax (SF−1) | 180 ± 9.06 | 117 ± 10.59 | *** |
| Vrev (mV) | 69.21 ± 2.38 | 77.33 ± 5.83 | |
| Cm (nF) | 5.26 ± 0.40 | 3.64 ± 0.48 | * |
| Availability | |||
| V1/2 (mV) | −31.03 ± 1.24 | −30.20 ± 1.43 | |
| k (mV) | 8.32 ± 0.42 | 9.32 ± 0.50 | |
| Calcium removal | |||
| koff,Fura (s−1) | 39.90 ± 2.48 | 40.73 ± 3.89 | |
| kon,S (µM−1s−1) | 26.71 ± 3.62 | 48.41 ± 16.81 | |
| koff,S (s−1) | 6.11 ± 0.76 | 5.11 ± 1.01 | |
| kNS (s−1) | 7,743 ± 1,256 | 8,114 ± 2,718 | |
| Calcium release flux (peak) | |||
| Activation | |||
| V1/2 (mV) | −10.81 ± 1.43 | −18.71 ± 0.80 | *** |
| k (mV) | 7.29 ± 0.39 | 7.76 ± 0.33 | |
| a (Ms−1V−1) | 1.11 ± 0.43 | 0.53 ± 0.15 | |
| b (Ms−1) | 0.245 ± 0.034 | 0.092 ± 0.017 | *** |
| Max (Ms−1) | 0.293 ± 0.047 | 0.119 ± 0.021 | ** |
| Availability | |||
| V1/2 (mV) | −37.95 ± 0.10 | −42.51 ± 1.18 | * |
| k (mV) | 5.68 ± 0.42 | 4.89 ± 0.26 | |
| Calcium release permeability (peak) | |||
| Activation | |||
| V1/2 (mV) | −5.81 ± 1.99 | −15.82 ± 2.31 | ** |
| k (mV) | 8.08 ± 0.48 | 9.10 ± 0.79 | |
| a (s−1mV−1) | 0.077 ± 0.095 | 0.169 ± 0.033 | |
| b (s−1) | 57.37 ± 5.94 | 26.97 ± 1.42 | *** |
| Max (s−1) | 60.92 ± 6.06 | 35.90 ± 1.83 | *** |
| Parameter | WT | R6/2 | Significance |
| L-type calcium current | |||
| Activation | |||
| V1/2 (mV) | 0.40 ± 0.56 | −6.20 ± 1.14 | *** |
| k (mV) | 5.05 ± 0.18 | 6.68 ± 0.46 | *** |
| gmax (SF−1) | 180 ± 9.06 | 117 ± 10.59 | *** |
| Vrev (mV) | 69.21 ± 2.38 | 77.33 ± 5.83 | |
| Cm (nF) | 5.26 ± 0.40 | 3.64 ± 0.48 | * |
| Availability | |||
| V1/2 (mV) | −31.03 ± 1.24 | −30.20 ± 1.43 | |
| k (mV) | 8.32 ± 0.42 | 9.32 ± 0.50 | |
| Calcium removal | |||
| koff,Fura (s−1) | 39.90 ± 2.48 | 40.73 ± 3.89 | |
| kon,S (µM−1s−1) | 26.71 ± 3.62 | 48.41 ± 16.81 | |
| koff,S (s−1) | 6.11 ± 0.76 | 5.11 ± 1.01 | |
| kNS (s−1) | 7,743 ± 1,256 | 8,114 ± 2,718 | |
| Calcium release flux (peak) | |||
| Activation | |||
| V1/2 (mV) | −10.81 ± 1.43 | −18.71 ± 0.80 | *** |
| k (mV) | 7.29 ± 0.39 | 7.76 ± 0.33 | |
| a (Ms−1V−1) | 1.11 ± 0.43 | 0.53 ± 0.15 | |
| b (Ms−1) | 0.245 ± 0.034 | 0.092 ± 0.017 | *** |
| Max (Ms−1) | 0.293 ± 0.047 | 0.119 ± 0.021 | ** |
| Availability | |||
| V1/2 (mV) | −37.95 ± 0.10 | −42.51 ± 1.18 | * |
| k (mV) | 5.68 ± 0.42 | 4.89 ± 0.26 | |
| Calcium release permeability (peak) | |||
| Activation | |||
| V1/2 (mV) | −5.81 ± 1.99 | −15.82 ± 2.31 | ** |
| k (mV) | 8.08 ± 0.48 | 9.10 ± 0.79 | |
| a (s−1mV−1) | 0.077 ± 0.095 | 0.169 ± 0.033 | |
| b (s−1) | 57.37 ± 5.94 | 26.97 ± 1.42 | *** |
| Max (s−1) | 60.92 ± 6.06 | 35.90 ± 1.83 | *** |
Best-fit parameters describing voltage dependence of activation and steady-state availability of L-type Ca2+ current and Ca2+ release and of the removal model used for calculating Ca2+ release flux. Numbers of experiments (WT vs. R6/2) were 17 versus 9 for L-type Ca2+ current activation and 20 versus 11 for availability, 19 versus 10 for Ca2+ removal fit and Ca2+ release activation, and 18 versus 11 for Ca2+ release availability. Vrev, reversal potential; Cm, linear capacitance; Max, maximal value at +50 mV. For definitions of the other parameters, see Materials and methods. *, P < 0.05; **, P < 0.01; ***, P < 0.001.