Table 2.

Kinetic models accurately recapitulate the single channel and macroscopic current responses of α1β3γ2L and α4β3γ2L receptor isoforms to a variety of GABA application protocols

	α1β3γ2L		α4β3γ2L
Parameter	Measured	Simulated	Measured	Simulated
Open Intervals (1 mm GABA)
τ1 (ms)	0.30*	0.30	0.35†	0.35
Fraction O1	0.24*	0.24	0.34†	0.32
τ2 (ms)	1.92*	1.92	1.30†	1.30
Fraction O2	0.48*	0.49	0.63†	0.65
τ3 (ms)	3.47*	3.47	6.30†	6.25
Fraction O3	0.28*	0.27	0.03†	0.03
Mean open time (ms)	2.14*	1.97	1.13†	1.16
Po	0.11*	0.08	0.35††	0.06
Desensitization (4 s, 1 mm GABA)
τ1 (ms)	6 ± 1	3	7 ± 1	7
Contribution A1	0.18 ± 0.03	0.18	0.25 ± 0.03	0.25
τ2 (ms)	56 ± 5	36	58 ± 4	49
Contribution A2	0.07 ± 0.01	0.10	0.13 ± 0.02	0.16
τ3 (ms)	431 ± 45	373	373 ± 41	392
Contribution A3	0.17 ± 0.03	0.22	0.17 ± 0.02	0.19
τ4 (ms)	2652 ± 250	1848	1934 ± 161	1406
Contribution A4	0.33 ± 0.03	0.32	0.33 ± 0.03	0.30
Residual Current	0.25 ± 0.02	0.18	0.12 ± 0.02	0.09
Deactivation (5 ms, 1 mm GABA)
Weighted τ (ms)	200 ± 24	214	371 ± 55	359
EC50
Peak (μm)	14	14	15	15
4 s (μm)	3.0	1.8	1.0	0.6
Repetitive Stimulation (5 ms, 1 mm GABA; final/initial peak)
2 pulses – 12.5 Hz	0.84 ± 0.02	0.77	0.60 ± 0.05	0.63
2 pulses – 1 Hz	0.89 ± 0.01	0.85	0.68 ± 0.04	0.65
2 pulses – 0.05 Hz	0.99 ± 0.01	0.99	0.92 ± 0.02	0.96
4 pulses – 10 Hz	0.75 ± 0.03	0.62	0.52 ± 0.06	0.46

^*Haas & Macdonald (1999).

^†Akk et al. (2004). ‡Note that this value overestimates the true P_o as it only reflects intracluster P_o.