Table 2.

Desensitization time constants

Group	Control	P Wd	Control	48 h THP
Duration of GABA application	400 ms	400 ms	5 s	5 s
τfast	31.1 ± 4.05	97.6 ± 17.1*	18.5 ± 4.2	63.2 ± 8.5*
% of total desensitization	80 ± 11	5 ± 2	34 ± 5	18 ± 4
τslow,1	308.6 ± 44.1	2888 ± 274*	205.1 ± 31.2	3100 ± 280*
% of total desensitization	18 ± 2	95 ± 1	14 ± 2	82 ± 11
τslow,2			2156 ± 236
% of total desensitization			52 ± 7
Weighted τ	87.3 ± 21.1	2546 ± 433*	1148 ± 272	2550 ± 265*
% Desensitization	86.1 ± 7.8	28.5 ± 3.4*	92.6 ± 5.6	36.2 ± 2.3*

Average values of τ (means ± s.e.m. in milliseconds) calculated for multiexponential desensitization kinetics and the combined weighted τ. Values were assessed following prolonged application of 5 mm GABA (400 ms, left or 5 s, right) to outside-out patches using a theta tube. Progesterone withdrawal (P Wd) and 48 h treatment with 3α,5β-THP (48 h THP) both resulted in a slower rate of desensitization best fitted as a biexponential function compared to control, where a three-exponential fit was optimal. In addition, the extent of desensitization compared to the peak current (% desensitization) was attenuated following steroid treatment. (n = 20–25 excised patches/group, ^*P < 0.05 versus control values).