Neurosteroid prolongs GABAA channel deactivation by altering kinetics of desensitized states - PubMed (original) (raw)
THDOC alters desensitization of currents elicited by 5 sec but not 200 msec taurine applications. A, Left, Averaged response of 10 applications of taurine (200 msec, 20 m
m
) to a granule neuron nucleated patch excised from a rat cerebellar slice (holding potential, −60 mV). Middle, Averaged response of the same patch as in the left panel to 20 m
m
taurine in the presence of THDOC (1 μ
m
). Right, Superimposed averaged currents recorded before and after the coapplication of taurine and THDOC. The averaged current in the middle panel has been normalized to the peak amplitude of the response in the _left panel. Above_each trace in the right and middle panels are shown the currents indicating the duration of the taurine applications. Vertical calibration bars do not apply to these currents. B, Left, Averaged response of 10 applications of taurine (5 sec, 20 m
m
) to a nucleated patch.Middle, Averaged response of the same patch as in the_left panel_ to 20 m
m
taurine in the presence of THDOC (1 μ
m
). Right, Superimposed normalized tail currents recorded before and after THDOC. C, Summary of the percentage of changes produced by THDOC on taurine-gated currents (200 msec applications). Amp, Peak amplitude;S/P, ratio between the amplitude at 200 msec (S) and peak amplitude (P); D_off, decay time constant at the end of the 200 msec application. Each_bar represents the mean ± SEM of nine patches studied.D, Summary of the percentage of changes produced by THDOC on taurine-gated currents (5 sec applications). Amp, Peak amplitude; S/P, ratio between the amplitude at 5 sec (S) and peak amplitude (P); Df and_Ds_ are the fast and slow desensitization time constants._Df_off and _Ds_off are the fast and slow decay time constant of deactivation at the end of the 5 sec application, and %F is the relative contribution of the fast component to peak amplitude. Each bar represents the mean ± SEM of eight patches studied.