Figure 7. α7 deletion altered the single channel profiles of the nAChRs.

Single channel recording conducted in the cell-attached configuration (ACh, 2.5 μM) in control neurones (control oligonucleotide treated, identical to untreated neurones) and in neurones treated with α7-antisense oligonucleotides indicates that the 18 pS/α-BgTx-sensitive, 35 pS/MLA-sensitive and the 50 pS/long duration channels are absent in the α7 minus neurones. A, single channel records from patches in control neurones. A subset of the channel classes detected in all such experiments are prominent in this recording (15, 35 and 50 pS short and long durations). The opening of the 18 and 65 pS classes that are also observed but at lower open frequency in most records are indicated by dotted lines. The slope conductance plot displays the conductances detected in this (continuous lines) and other (dotted lines) control patches. B, single channel profiles from 60 % recordings obtained from α7 minus neurones include openings of three major conductance channels (15, 35 and 50 pS). The 18 pS channel was absent in all α7 minus neurones. Analysis of the pharmacology and open time kinetics of the channels of 35 and 50 pS conductances further revealed that (a) long burst, 50 pS openings were absent in α7 minus neurones (see Fig. 8) and (b) that 35 pS, MLA-sensitive channels were deleted. The 35 pS conductance channels detected following α7 deletion are likely to be a novel class (Fig. 8). C, single channel recordings from 40 % of the patches from α7 minus neurones revealed that all 50 pS channel openings were absent. In addition, a novel channel class of 60 pS conductance was detected.