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. 2005 Dec 14;25(50):11605–11613. doi: 10.1523/JNEUROSCI.4173-05.2005

Figure 3.

Figure 3.

Patch excision after steroid preincubation and removal does not affect potentiation, suggesting that membrane-accumulated steroid is sufficient for receptor potentiation. A, Channel activity in an inside-out patch from a cell to which ACN was preapplied and then removed before seal formation. The receptors were exposed to 50 μm GABA in the patch pipette. A1, Channel record from 1 min after excision. Histograms pertain to data from 0–2 min after excision. The open times were 0.31 ms (42%), 2.1 ms (23%), and 18.5 ms (35%). The closed times were 0.20 ms (58%), 1.2 ms (32%), and 18.5 ms (9%). A2, The addition of 5 mm methyl-β-cyclodextrin to the bath to remove steroid resulted in an immediate loss of steroid-mediated potentiation. The open times were 0.46 ms (24%), 3.4 ms (57%), and 6.9 ms (19%). The closed times were 0.15 ms (60%), 1.5 ms (9%), and 10.4 ms (31%). B, Time course of the effect of patch excision on channel activity from cells pretreated with ACN(filled circles) or in the presence of GABA alone (open circles). Mean open time was averaged over 1 min blocks. Note the prolonged potentiation of channel activity after ACN pre-exposure and removal. Data show mean ± SD from three to six patches.